Using a GUID in Routing - Code

SQL

Alter POHeader table

ALTER TABLE POHeader ADD [POHeaderGuid] uniqueidentifier NOT NULL DEFAULT NEWID();

Create POHeader table (if starting from scratch)

USE [PurchaseOrders]
GO
IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[POHeader]') AND type in (N'U'))
ALTER TABLE [dbo].[POHeader] DROP CONSTRAINT IF EXISTS [DF__POHeader__POHead__6C6E1476]
GO
IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[POHeader]') AND type in (N'U'))
ALTER TABLE [dbo].[POHeader] DROP CONSTRAINT IF EXISTS [DF_POHeader_POHeaderIsArchived]
GO
IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[POHeader]') AND type in (N'U'))
ALTER TABLE [dbo].[POHeader] DROP CONSTRAINT IF EXISTS [DF_POHeader_POHeaderOrderNumber]
GO
/****** Object:  Table [dbo].[POHeader]    Script Date: 13/06/2021 17:54:15 ******/
DROP TABLE IF EXISTS [dbo].[POHeader]
GO
/****** Object:  Table [dbo].[POHeader]    Script Date: 13/06/2021 17:54:15 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[POHeader](
	[POHeaderID] [int] IDENTITY(1,1) NOT NULL,
	[POHeaderOrderNumber] [int] NOT NULL,
	[POHeaderOrderDate] [datetime] NOT NULL,
	[POHeaderSupplierID] [int] NOT NULL,
	[POHeaderSupplierAddress1] [nvarchar](50) NULL,
	[POHeaderSupplierAddress2] [nvarchar](50) NULL,
	[POHeaderSupplierAddress3] [nvarchar](50) NULL,
	[POHeaderSupplierPostCode] [nvarchar](10) NULL,
	[POHeaderSupplierEmail] [nvarchar](256) NULL,
	[POHeaderRequestedBy] [nvarchar](450) NULL,
	[POHeaderIsArchived] [bit] NOT NULL,
	[POHeaderGuid] [uniqueidentifier] NOT NULL,
 CONSTRAINT [PK_POHeader] PRIMARY KEY CLUSTERED 
(
	[POHeaderID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, OPTIMIZE_FOR_SEQUENTIAL_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[POHeader] ADD  CONSTRAINT [DF_POHeader_POHeaderOrderNumber]  DEFAULT ((0)) FOR [POHeaderOrderNumber]
GO
ALTER TABLE [dbo].[POHeader] ADD  CONSTRAINT [DF_POHeader_POHeaderIsArchived]  DEFAULT ((0)) FOR [POHeaderIsArchived]
GO
ALTER TABLE [dbo].[POHeader] ADD  DEFAULT (newid()) FOR [POHeaderGuid]
GO

Drop and recreate POHeaderList

USE [PurchaseOrders]
GO
IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[POHeader]') AND type in (N'U'))
ALTER TABLE [dbo].[POHeader] DROP CONSTRAINT IF EXISTS [DF__POHeader__POHead__6C6E1476]
GO
IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[POHeader]') AND type in (N'U'))
ALTER TABLE [dbo].[POHeader] DROP CONSTRAINT IF EXISTS [DF_POHeader_POHeaderIsArchived]
GO
IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[POHeader]') AND type in (N'U'))
ALTER TABLE [dbo].[POHeader] DROP CONSTRAINT IF EXISTS [DF_POHeader_POHeaderOrderNumber]
GO
/****** Object:  Table [dbo].[POHeader]    Script Date: 13/06/2021 17:54:15 ******/
DROP TABLE IF EXISTS [dbo].[POHeader]
GO
/****** Object:  Table [dbo].[POHeader]    Script Date: 13/06/2021 17:54:15 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[POHeader](
	[POHeaderID] [int] IDENTITY(1,1) NOT NULL,
	[POHeaderOrderNumber] [int] NOT NULL,
	[POHeaderOrderDate] [datetime] NOT NULL,
	[POHeaderSupplierID] [int] NOT NULL,
	[POHeaderSupplierAddress1] [nvarchar](50) NULL,
	[POHeaderSupplierAddress2] [nvarchar](50) NULL,
	[POHeaderSupplierAddress3] [nvarchar](50) NULL,
	[POHeaderSupplierPostCode] [nvarchar](10) NULL,
	[POHeaderSupplierEmail] [nvarchar](256) NULL,
	[POHeaderRequestedBy] [nvarchar](450) NULL,
	[POHeaderIsArchived] [bit] NOT NULL,
	[POHeaderGuid] [uniqueidentifier] NOT NULL,
 CONSTRAINT [PK_POHeader] PRIMARY KEY CLUSTERED 
(
	[POHeaderID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, OPTIMIZE_FOR_SEQUENTIAL_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[POHeader] ADD  CONSTRAINT [DF_POHeader_POHeaderOrderNumber]  DEFAULT ((0)) FOR [POHeaderOrderNumber]
GO
ALTER TABLE [dbo].[POHeader] ADD  CONSTRAINT [DF_POHeader_POHeaderIsArchived]  DEFAULT ((0)) FOR [POHeaderIsArchived]
GO
ALTER TABLE [dbo].[POHeader] ADD  DEFAULT (newid()) FOR [POHeaderGuid]
GO

Create POHeader_GetOneByGuid

USE [PurchaseOrders]
GO

/****** Object:  StoredProcedure [dbo].[spPOHeader_GetOneByGuid]    Script Date: 13/06/2021 17:56:43 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

--------------  Stored Proc for SELECT (one)
CREATE PROCEDURE [dbo].[spPOHeader_GetOneByGuid]
-- Needs one parameter for primary key
@POHeaderGuid uniqueidentifier
AS 
BEGIN
-- SQL Select for one table row
SELECT  dbo.POHeader.POHeaderID, dbo.POHeader.POHeaderOrderNumber, dbo.POHeader.POHeaderOrderDate, dbo.POHeader.POHeaderSupplierID, dbo.POHeader.POHeaderSupplierAddress1, dbo.POHeader.POHeaderSupplierAddress2, dbo.POHeader.POHeaderSupplierAddress3, dbo.POHeader.POHeaderSupplierPostCode, dbo.POHeader.POHeaderSupplierEmail, dbo.POHeader.POHeaderRequestedBy, 
           dbo.POHeader.POHeaderIsArchived, dbo.Supplier.SupplierName, SUM(ISNULL(dbo.POLine.POLineProductQuantity * dbo.POLine.POLineProductUnitPrice, 0)) AS NetPrice, SUM(ISNULL(dbo.POLine.POLineProductQuantity * dbo.POLine.POLineProductUnitPrice * dbo.POLine.POLineTaxRate, 0)) AS Tax, SUM(ISNULL((dbo.POLine.POLineProductQuantity * dbo.POLine.POLineProductUnitPrice) 
           * (1 + dbo.POLine.POLineTaxRate), 0)) AS TotalOrderValue
FROM    dbo.POHeader LEFT OUTER JOIN
           dbo.POLine ON dbo.POHeader.POHeaderID = dbo.POLine.POLineHeaderID LEFT OUTER JOIN
           dbo.Supplier ON dbo.POHeader.POHeaderSupplierID = dbo.Supplier.SupplierID
		   WHERE POHeaderGuid= @POHeaderGuid
GROUP BY dbo.POHeader.POHeaderID, dbo.POHeader.POHeaderOrderNumber, dbo.POHeader.POHeaderOrderDate, dbo.POHeader.POHeaderSupplierID, dbo.POHeader.POHeaderSupplierAddress1, dbo.POHeader.POHeaderSupplierAddress2, dbo.POHeader.POHeaderSupplierAddress3, dbo.POHeader.POHeaderSupplierPostCode, dbo.POHeader.POHeaderSupplierEmail, dbo.POHeader.POHeaderRequestedBy, 
           dbo.Supplier.SupplierName, dbo.POHeader.POHeaderIsArchived

END

GO

C#

POHeader.cs

using System;
using System.ComponentModel.DataAnnotations;
// This is the model for one row in the database table.
namespace BlazorPurchaseOrders.Data
{
    public class POHeader
    {
        [Required]
        public int POHeaderID { get; set; }

        [Required]
        public int POHeaderOrderNumber { get; set; }

        [Required]
        public DateTime POHeaderOrderDate { get; set; }

        [Required]
        public int POHeaderSupplierID { get; set; }

        [StringLength(50, ErrorMessage = "'Address' has a maximum length of 50 characters.")]
        public string POHeaderSupplierAddress1 { get; set; }

        [StringLength(50, ErrorMessage = "'Address' has a maximum length of 50 characters.")]
        public string POHeaderSupplierAddress2 { get; set; }

        [StringLength(50, ErrorMessage = "'Address' has a maximum length of 50 characters.")]
        public string POHeaderSupplierAddress3 { get; set; }

        [StringLength(10, ErrorMessage = "'Post Code' has a maximum length of 10 characters.")]
        public string POHeaderSupplierPostCode { get; set; }

        [StringLength(256, ErrorMessage = "'Email' has a maximum length of 256 characters.")]
        [EmailAddress(ErrorMessage = "Invalid Email Address format.")]
        public string POHeaderSupplierEmail { get; set; }

        [StringLength(450)]
        public string POHeaderRequestedBy { get; set; }

        [Required]
        public bool POHeaderIsArchived { get; set; }

        public System.Guid POHeaderGuid { get; set; }

        public string SupplierName { get; }

        public decimal TotalOrderValue { get; }
        public decimal NetPrice { get; }

        public decimal Tax { get; }
    }
}

POHeaderService.cs

using Dapper;
using Microsoft.Data.SqlClient;
using System;
using System.Collections.Generic;
using System.Data;
using System.Threading.Tasks;

namespace BlazorPurchaseOrders.Data
{
    public class POHeaderService : IPOHeaderService
    {
        // Database connection
        private readonly SqlConnectionConfiguration _configuration;
        public POHeaderService(SqlConnectionConfiguration configuration)
        {
            _configuration = configuration;
        }

        // Add (create) a POHeader table row (SQL Insert)
        public async Task<int> POHeaderInsert(
                DateTime POHeaderOrderDate,                
                int POHeaderSupplierID,
                string POHeaderSupplierAddress1,
                string POHeaderSupplierAddress2,
                string POHeaderSupplierAddress3,
                string POHeaderSupplierPostCode,
                string POHeaderSupplierEmail,
                string POHeaderRequestedBy)
        {
            int newHeaderID = 0;
            using (var conn = new SqlConnection(_configuration.Value))
            {                
                var parameters = new DynamicParameters();                
                parameters.Add("POHeaderOrderDate", POHeaderOrderDate, DbType.Date);
                parameters.Add("POHeaderSupplierID", POHeaderSupplierID, DbType.Int32);
                parameters.Add("POHeaderSupplierAddress1", POHeaderSupplierAddress1, DbType.String);
                parameters.Add("POHeaderSupplierAddress2", POHeaderSupplierAddress2, DbType.String);
                parameters.Add("POHeaderSupplierAddress3", POHeaderSupplierAddress3, DbType.String);
                parameters.Add("POHeaderSupplierPostCode", POHeaderSupplierPostCode, DbType.String);
                parameters.Add("POHeaderSupplierEmail", POHeaderSupplierEmail, DbType.String);
                parameters.Add("POHeaderRequestedBy", POHeaderRequestedBy, DbType.String);

                parameters.Add("@Output", DbType.Int32, direction: ParameterDirection.Output);

                // Stored procedure method
                await conn.ExecuteAsync("spPOHeader_Insert", parameters, commandType: CommandType.StoredProcedure);

                newHeaderID = parameters.Get<int>("@Output");
            };
            return newHeaderID;
        }


        // Get a list of poheader rows (SQL Select)
        public async Task<IEnumerable<POHeader>> POHeaderList(string @UserName)
        {
            IEnumerable<POHeader> poheaders;
            var parameters = new DynamicParameters();
            parameters.Add("@UserName", UserName);
            using (var conn = new SqlConnection(_configuration.Value))
            {
                poheaders = await conn.QueryAsync<POHeader>("spPOHeader_List", parameters, commandType: CommandType.StoredProcedure);
            }
            return poheaders;
        }

        // Get one poheader based on its POHeaderID (SQL Select)
        // This only works if you're already created the stored procedure.
        public async Task<POHeader> POHeader_GetOne(int @POHeaderID)
        {
            POHeader poheader = new POHeader();
            var parameters = new DynamicParameters();
            parameters.Add("@POHeaderID", POHeaderID, DbType.Int32);
            using (var conn = new SqlConnection(_configuration.Value))
            {
                poheader = await conn.QueryFirstOrDefaultAsync<POHeader>("spPOHeader_GetOne", parameters, commandType: CommandType.StoredProcedure);
            }
            return poheader;
        }

        public async Task<POHeader> POHeader_GetOneByGuid(Guid @POHeaderGuid)
        {
            POHeader poheader = new POHeader();
            var parameters = new DynamicParameters();
            parameters.Add("@POHeaderGuid", POHeaderGuid, DbType.Guid);
            using (var conn = new SqlConnection(_configuration.Value))
            {
                poheader = await conn.QueryFirstOrDefaultAsync<POHeader>("spPOHeader_GetOneByGuid", parameters, commandType: CommandType.StoredProcedure);
            }
            return poheader;
        }

        // Update one POHeader row based on its POHeaderID (SQL Update)
        // This only works if you're already created the stored procedure.
        public async Task<bool> POHeaderUpdate(POHeader poheader)
        {
            using (var conn = new SqlConnection(_configuration.Value))
            {
                var parameters = new DynamicParameters();
                parameters.Add("POHeaderID", poheader.POHeaderID, DbType.Int32);

                parameters.Add("POHeaderOrderNumber", poheader.POHeaderOrderNumber, DbType.Int32);
                parameters.Add("POHeaderOrderDate", poheader.POHeaderOrderDate, DbType.Date);
                parameters.Add("POHeaderSupplierID", poheader.POHeaderSupplierID, DbType.Int32);
                parameters.Add("POHeaderSupplierAddress1", poheader.POHeaderSupplierAddress1, DbType.String);
                parameters.Add("POHeaderSupplierAddress2", poheader.POHeaderSupplierAddress2, DbType.String);
                parameters.Add("POHeaderSupplierAddress3", poheader.POHeaderSupplierAddress3, DbType.String);
                parameters.Add("POHeaderSupplierPostCode", poheader.POHeaderSupplierPostCode, DbType.String);
                parameters.Add("POHeaderSupplierEmail", poheader.POHeaderSupplierEmail, DbType.String);
                parameters.Add("POHeaderRequestedBy", poheader.POHeaderRequestedBy, DbType.String);
                parameters.Add("POHeaderIsArchived", poheader.POHeaderIsArchived, DbType.Boolean);

                await conn.ExecuteAsync("spPOHeader_Update", parameters, commandType: CommandType.StoredProcedure);
            }
            return true;
        }

    }
}

IPOHeaderService.cs

using System;
using System.Collections.Generic;
using System.Threading.Tasks;

namespace BlazorPurchaseOrders.Data
{
    // Each item below provides an interface to a method in POHeaderServices.cs
    public interface IPOHeaderService
    {
        Task<int> POHeaderInsert(
            DateTime POHeaderOrderDate,
            int POHeaderSupplierID,
            string POHeaderSupplierAddress1,
            string POHeaderSupplierAddress2,
            string POHeaderSupplierAddress3,
            string POHeaderSupplierPostCode,
            string POHeaderSupplierEmail,
            string POHeaderRequestedBy
            );
        Task<IEnumerable<POHeader>> POHeaderList(string @UserName);
        Task<POHeader> POHeader_GetOne(int POHeaderID);
        Task<POHeader> POHeader_GetOneByGuid(Guid POHeaderGuid);
        Task<bool> POHeaderUpdate(POHeader poheader);
    }
}

Index.razor

@page "/"
@using BlazorPurchaseOrders.Data

@inject IPOHeaderService POHeaderService
@inject NavigationManager NavigationManager
@inject IJSRuntime IJS

@attribute [Microsoft.AspNetCore.Authorization.AllowAnonymous]

@inject AuthenticationStateProvider AuthenticationStateProvider

<div class="col-sm-12">
    <AuthorizeView>
        <NotAuthorized>
            <h5>Please Log in</h5>
            <h6>or</h6>
            <h5>Register to use Blazor Purchase Orders</h5>
        </NotAuthorized>
        <Authorized>
            <h3>Purchase Orders</h3>
            <br />
            <SfGrid DataSource="@poheader"
                    Toolbar="Toolbaritems">
                <GridEvents RowSelected="RowSelectHandler" OnToolbarClick="ToolbarClickHandler" TValue="POHeader"></GridEvents>
                <GridColumns>
                    <GridColumn Field="@nameof(POHeader.POHeaderOrderNumber)"
                                HeaderText="No"
                                TextAlign="@TextAlign.Left"
                                Width="10">
                    </GridColumn>
                    <GridColumn Field="@nameof(POHeader.POHeaderOrderDate)"
                                HeaderText="Date"
                                Format="d"
                                Type="ColumnType.Date"
                                TextAlign="@TextAlign.Center"
                                Width="15">
                    </GridColumn>
                    <GridColumn Field="@nameof(POHeader.SupplierName)"
                                HeaderText="Supplier"
                                TextAlign="@TextAlign.Left"
                                Width="40">
                    </GridColumn>
                    <GridColumn Field="@nameof(POHeader.TotalOrderValue)"
                                HeaderText="Value"
                                TextAlign="@TextAlign.Right"
                                Format="C2"
                                Width="20">
                    </GridColumn>
                    <GridColumn Field="@nameof(POHeader.POHeaderRequestedBy)"
                                HeaderText="Requested by"
                                TextAlign="@TextAlign.Left"
                                Width="40">
                    </GridColumn>
                </GridColumns>
            </SfGrid>

            <WarningPage @ref="Warning" WarningHeaderMessage="@WarningHeaderMessage" WarningContentMessage="@WarningContentMessage" />

            <ConfirmPage @ref="ConfirmOrderDelete" ConfirmHeaderMessage="@ConfirmHeaderMessage" ConfirmContentMessage="@ConfirmContentMessage" ConfirmationChanged="ConfirmOrderArchive" />

        </Authorized>
    </AuthorizeView>
</div>

@code {

    // Create an empty list, named poheader, of empty POHeader objects.
    IEnumerable<POHeader> poheader;
    POHeader orderHeader = new POHeader();

    private List<ItemModel> Toolbaritems = new List<ItemModel>();

    int POHeaderID = 0;

    private int selectedPOHeaderID { get; set; } = 0;
    private Guid selectedPOHeaderGuid { get; set; }

    WarningPage Warning;
    string WarningHeaderMessage = "";
    string WarningContentMessage = "";

    ConfirmPage ConfirmOrderDelete;
    string ConfirmHeaderMessage = "";
    string ConfirmContentMessage = "";
    public bool ConfirmationChanged { get; set; } = false;

    [CascadingParameter]
    private Task<AuthenticationState> authenticationStateTask { get; set; }

    protected override async Task OnInitializedAsync()
    {
        //Populate the list of orders objects from the Purchase Order Header table.
        await GetOrderList();

        Toolbaritems.Add(new ItemModel() { Text = "Add", TooltipText = "Add a new order", PrefixIcon = "e-add" });
        Toolbaritems.Add(new ItemModel() { Text = "Edit", TooltipText = "Edit selected order", PrefixIcon = "e-edit" });
        Toolbaritems.Add(new ItemModel() { Text = "Delete", TooltipText = "Delete selected order", PrefixIcon = "e-delete" });
        Toolbaritems.Add(new ItemModel() { Text = "Preview", TooltipText = "Preview selected order", PrefixIcon = "e-print" });
    }


    public async Task ToolbarClickHandler(Syncfusion.Blazor.Navigations.ClickEventArgs args)
    {
        if (args.Item.Text == "Add")
        {
            //Code for adding goes here
            POHeaderID = 0;
            NavigationManager.NavigateTo($"/purchaseorder/{Guid.Empty}");
        }

        if (args.Item.Text == "Edit")
        {
            //Code for editing - Check that an Order has been selected from the grid
            if (selectedPOHeaderID == 0)
            {
                WarningHeaderMessage = "Warning!";
                WarningContentMessage = "Please select an Order from the grid.";
                Warning.OpenDialog();
            }
            else
            {
                NavigationManager.NavigateTo($"/purchaseorder/{selectedPOHeaderGuid}");
            }
        }

        if (args.Item.Text == "Delete")
        {
            //Code for deleting
            if (selectedPOHeaderID == 0)    //Check that an order has been selected
            {
                WarningHeaderMessage = "Warning!";
                WarningContentMessage = "Please select an Order from the grid.";
                Warning.OpenDialog();
            }
            else
            {
                //Populate orderHeader using selectedPOHeaderID
                orderHeader = await POHeaderService.POHeader_GetOne(selectedPOHeaderID);

                ConfirmHeaderMessage = "Confirm Deletion";
                ConfirmContentMessage = "Please confirm that this order should be deleted.";
                ConfirmOrderDelete.OpenDialog();
            }
        }

        if (args.Item.Text == "Preview")
        {

            //Code for editing - Check that an Order has been selected from the grid
            if (selectedPOHeaderID == 0)
            {
                WarningHeaderMessage = "Warning!";
                WarningContentMessage = "Please select an Order from the grid.";
                Warning.OpenDialog();
            }
            else
            {
                await IJS.InvokeAsync<object>("open", new object[] { "/previeworder/" + selectedPOHeaderGuid + "", "_blank" });
            }
        }
    }

    public void RowSelectHandler(RowSelectEventArgs<POHeader> args)
    {
        //{args.Data} returns the current selected records.
        selectedPOHeaderID = args.Data.POHeaderID;
        selectedPOHeaderGuid = args.Data.POHeaderGuid;
    }


    protected async Task ConfirmOrderArchive(bool archiveConfirmed)
    {
        if (archiveConfirmed)
        {
            orderHeader.POHeaderIsArchived = true;
            bool Success = await POHeaderService.POHeaderUpdate(orderHeader);
            await GetOrderList();
            StateHasChanged();
        }
    }

    protected async Task GetOrderList()
    {
        var user = (await authenticationStateTask).User;

        if (user.IsInRole("Admin") || user.IsInRole("Manager"))
        {
            poheader = await POHeaderService.POHeaderList(null);   //leave user name blank
        }
        else
        {
            poheader = await POHeaderService.POHeaderList(user.Identity.Name); //pass user name
        }
    }
}

PreviewOrderPage.razor

@page "/previeworder/{POHeaderGuid:guid}"
@layout BlankLayout


@using BlazorPurchaseOrders.Data;
@inject IPOHeaderService POHeaderService
@inject IPOLineService POLineService

@attribute [Microsoft.AspNetCore.Authorization.AllowAnonymous]

<!DOCTYPE html>
<html>

<body>
    <div class="invoice-box">
        <table>
            <tr class="addressbar">
                <td class="addressbar-left">
                    <img src="https://blazorcode.uk/media/files/blazorcode_logo_small.png" style="width: 100%; max-width: 300px" />
                </td>

                <td class="addressbar-right">
                    blazorcode.uk<br />
                    5 High Street<br />
                    Trumpington <br />
                    TR4A IRS
                </td>
            </tr>
        </table>
        <br />
        <table>
            <tr class="addressbar">
                <td style="width:50%">
                    @orderHeader.SupplierName<br />
                    @if (!String.IsNullOrEmpty(orderHeader.POHeaderSupplierAddress1))
                    {
                        @orderHeader.POHeaderSupplierAddress1<br />
                    }
                    @if (!String.IsNullOrEmpty(orderHeader.POHeaderSupplierAddress2))
                    {
                        @orderHeader.POHeaderSupplierAddress2<br />
                    }
                    @if (!String.IsNullOrEmpty(orderHeader.POHeaderSupplierAddress3))
                    {
                        @orderHeader.POHeaderSupplierAddress3<br />
                    }
                    @orderHeader.POHeaderSupplierPostCode<br />
                </td>
                <td style="width:15%">
                    Order No<br />
                    Order Date<br />
                    Contact
                </td>
                <td style="width:35%">
                    : @orderHeader.POHeaderOrderNumber<br />
                    : @orderHeader.POHeaderOrderDate.ToShortDateString()<br />
                    : @orderHeader.POHeaderRequestedBy
                </td>
            </tr>
        </table>
        <table>
            <tr class="doctype">
                <td>PURCHASE ORDER</td>
            </tr>
        </table>
        <table>
            <tr class="heading">
                <th>Code</th>
                <th>Description</th>
                <th class="column-right">Quantity</th>
                <th class="column-right">Unit Price</th>
                <th class="column-right">Net Price</th>
                <th class="column-right">Tax Rate</th>
                <th class="column-right">Tax</th>
                <th class="column-right">Total</th>
            </tr>
            @foreach (var orderline in orderLines)
            {
                <tr class="item">
                    <td>@orderline.POLineProductCode</td>
                    <td>@orderline.POLineProductDescription</td>
                    <td class="column-right">@String.Format("{0:N0}", orderline.POLineProductQuantity)</td>
                    <td class="column-right">@String.Format("{0:C2}", orderline.POLineProductUnitPrice)</td>
                    <td class="column-right">@String.Format("{0:C2}", orderline.POLineNetPrice)</td>
                    <td class="column-right">@String.Format("{0:P2}", orderline.POLineTaxRate)</td>
                    <td class="column-right">@String.Format("{0:C2}", orderline.POLineTaxAmount)</td>
                    <td class="column-right">@String.Format("{0:C2}", orderline.POLineGrossPrice)</td>
                </tr>
            }
            <tr class="totals">
                <td></td>
                <td class="column-left">Order Total:</td>
                <td></td>
                <td></td>
                <td>@String.Format("{0:C2}", orderHeader.NetPrice)</td>
                <td></td>
                <td>@String.Format("{0:C2}", orderHeader.Tax)</td>
                <td>@String.Format("{0:C2}", orderHeader.TotalOrderValue)</td>
            </tr>
        </table>

    </div>
</body>
</html>

<style>
    .invoice-box {
        max-width: 1000px;
        margin: auto;
        padding: 30px;
        border: 1px solid #eee;
        box-shadow: 0 0 10px rgba(0, 0, 0, 0.15);
        font-size: 16px;
        line-height: 24px;
        font-family: 'Helvetica Neue', 'Helvetica', Helvetica, Arial, sans-serif;
        color: #555;
    }

        .invoice-box table {
            width: 100%;
            line-height: inherit;
            text-align: left;
        }

    .addressbar {
        vertical-align: top;
    }

    .addressbar-left {
        text-align: left;
    }

    .addressbar-right {
        text-align: right;
        font-weight: bold;
        padding-top: 5px;
    }

    .doctype {
        font-size: 20px;
        line-height: 80px;
        color: #333;
        font-weight: bold;
        text-align: center
    }

    .heading {
        background: #eee;
        border-bottom: 1px solid #ddd;
        font-weight: bold;
    }

    .column-left {
        text-align: left;
    }

    .column-right {
        text-align: right;
    }

    .item {
        border-bottom: 1px solid #eee;
    }

    .totals {
        background: #eee;
        font-weight: bold;
        line-height: 40px;
        text-align: right;
    }
</style>

@code {
    IEnumerable<POLine> orderLinesByPOHeader;
    public List<POLine> orderLines = new List<POLine>();
    POHeader orderHeader = new POHeader();

    public int POHeaderID { get; set; }

    [Parameter]
    public Guid POHeaderGuid { get; set; }

    protected override async Task OnInitializedAsync()
    {
        orderHeader = await POHeaderService.POHeader_GetOneByGuid(POHeaderGuid);
        POHeaderID = orderHeader.POHeaderID;
        orderLinesByPOHeader = await POLineService.POLine_GetByPOHeader(POHeaderID);
        orderLines = orderLinesByPOHeader.ToList(); //Convert from IEnumable to List
    }

}        
        

PurchaseOrderPage.razor

@page "/purchaseorder/{POHeaderGuid:guid}"
@using BlazorPurchaseOrders.Data

@inject NavigationManager NavigationManager
@inject ISupplierService SupplierService
@inject IPOHeaderService POHeaderService
@inject IPOLineService POLineService
@inject IProductService ProductService
@inject ITaxService TaxService


@using Microsoft.AspNetCore.Components.Authorization
@inject AuthenticationStateProvider AuthenticationStateProvider
@using System
@using System.Collections.Generic


<h3>@pagetitle</h3>

<EditForm Model="@orderaddedit" OnValidSubmit="@OrderSave">
    <DataAnnotationsValidator />
    <div class="grid-container">
        <div class="grid-child left-column">
            <SfDropDownList DataSource="@supplier"
                            TItem="Supplier"
                            TValue="int"
                            Text="SupplierID"
                            @bind-Value="orderaddedit.POHeaderSupplierID"
                            FloatLabelType="@FloatLabelType.Auto"
                            Placeholder="Select a Supplier"
                            Enabled="@supplierEnabled">
                <DropDownListFieldSettings Text="SupplierName" Value="SupplierID"></DropDownListFieldSettings>
                <DropDownListEvents TItem="Supplier" TValue="int" ValueChange="OnChangeSupplier"></DropDownListEvents>
            </SfDropDownList>

            <SfTextBox Enabled="true" Placeholder="Address"
                       FloatLabelType="@FloatLabelType.Always"
                       @bind-Value="orderaddedit.POHeaderSupplierAddress1"></SfTextBox>
            <ValidationMessage For="@(() => orderaddedit.POHeaderSupplierAddress1)" />

            <SfTextBox Enabled="true" Placeholder=""
                       FloatLabelType="@FloatLabelType.Never"
                       @bind-Value="orderaddedit.POHeaderSupplierAddress2"></SfTextBox>
            <ValidationMessage For="@(() => orderaddedit.POHeaderSupplierAddress2)" />

            <SfTextBox Enabled="true" Placeholder=""
                       FloatLabelType="@FloatLabelType.Never"
                       @bind-Value="orderaddedit.POHeaderSupplierAddress3"></SfTextBox>
            <ValidationMessage For="@(() => orderaddedit.POHeaderSupplierAddress3)" />

            <SfTextBox Enabled="true" Placeholder="Post Code"
                       FloatLabelType="@FloatLabelType.Never"
                       @bind-Value="orderaddedit.POHeaderSupplierPostCode"></SfTextBox>
            <ValidationMessage For="@(() => orderaddedit.POHeaderSupplierPostCode)" />

            <SfTextBox Enabled="true" Placeholder="Email"
                       FloatLabelType="@FloatLabelType.Auto"
                       @bind-Value="orderaddedit.POHeaderSupplierEmail"></SfTextBox>
            <ValidationMessage For="@(() => orderaddedit.POHeaderSupplierEmail)" />
        </div>
        <div class="grid-child right-column">
            <SfNumericTextBox Enabled="false" Placeholder="Order No"
                              FloatLabelType="@FloatLabelType.Always"
                              ShowSpinButton="false"
                              @bind-Value="orderaddedit.POHeaderOrderNumber"></SfNumericTextBox>

            <SfDatePicker TValue="DateTime"
                          Placeholder='Order Date'
                          FloatLabelType="@FloatLabelType.Auto"
                          @bind-Value="orderaddedit.POHeaderOrderDate"></SfDatePicker>

            <SfTextBox Enabled="false" Placeholder="Requested by"
                       FloatLabelType="@FloatLabelType.Always"
                       @bind-Value="orderaddedit.POHeaderRequestedBy"></SfTextBox>
        </div>
    </div>
    <br />
    <SfGrid @ref="OrderLinesGrid"
            DataSource="@orderLines"
            Toolbar="@Toolbaritems"
            AllowResizing="true">
        <GridColumns>
            <GridColumn Field="@nameof(POLine.POLineProductCode)"
                        HeaderText="Product"
                        TextAlign="@TextAlign.Left"
                        Width="20">
            </GridColumn>
            <GridColumn Field="@nameof(POLine.POLineProductDescription)"
                        HeaderText="Description"
                        TextAlign="@TextAlign.Left"
                        Width="30">
            </GridColumn>
            <GridColumn Field="@nameof(POLine.POLineProductQuantity)"
                        HeaderText="Quantity"
                        TextAlign="@TextAlign.Right"
                        Format="n0"
                        Width="10">
            </GridColumn>
            <GridColumn Field="@nameof(POLine.POLineProductUnitPrice)"
                        HeaderText="Unit Price"
                        TextAlign="@TextAlign.Right"
                        Format="C2"
                        Width="10">
            </GridColumn>
            <GridColumn Field="@nameof(POLine.POLineNetPrice)"
                        HeaderText="Net Price"
                        TextAlign="@TextAlign.Right"
                        Format="C2"
                        Width="10">
            </GridColumn>
            <GridColumn Field="@nameof(POLine.POLineTaxRate)"
                        HeaderText="Tax Rate"
                        TextAlign="@TextAlign.Right"
                        Format="p2"
                        Width="10">
            </GridColumn>
            <GridColumn Field="@nameof(POLine.POLineTaxAmount)"
                        HeaderText="Tax"
                        TextAlign="@TextAlign.Right"
                        Format="C2"
                        Width="10">
            </GridColumn>
            <GridColumn Field="@nameof(POLine.POLineGrossPrice)"
                        HeaderText="Total"
                        TextAlign="@TextAlign.Right"
                        Format="C2"
                        Width="10">
            </GridColumn>
        </GridColumns>

        <GridAggregates>
            <GridAggregate>
                <GridAggregateColumns>
                    <GridAggregateColumn Field=@nameof(POLine.POLineNetPrice) Type="AggregateType.Sum" Format="C2">
                        <FooterTemplate Context="NetContext">
                            @{
                                var aggregate = NetContext as AggregateTemplateContext;
                                <div>
                                    <p>@aggregate.Sum</p>
                                </div>
                            }
                        </FooterTemplate>
                    </GridAggregateColumn>

                    <GridAggregateColumn Field=@nameof(POLine.POLineTaxAmount) Type="AggregateType.Sum" Format="C2">
                        <FooterTemplate Context="TaxContext">
                            @{
                                var aggregate = TaxContext as AggregateTemplateContext;
                                <div>
                                    <p>@aggregate.Sum</p>
                                </div>
                            }
                        </FooterTemplate>
                    </GridAggregateColumn>

                    <GridAggregateColumn Field=@nameof(POLine.POLineGrossPrice) Type="AggregateType.Sum" Format="C2">
                        <FooterTemplate Context="GrossContext">
                            @{
                                var aggregate = GrossContext as AggregateTemplateContext;
                                <div>
                                    <p>@aggregate.Sum</p>
                                </div>
                            }
                        </FooterTemplate>
                    </GridAggregateColumn>
                </GridAggregateColumns>
            </GridAggregate>

        </GridAggregates>
        <GridEvents RowSelected="RowSelectHandler" OnToolbarClick="ToolbarClickHandler" TValue="POLine"></GridEvents>
    </SfGrid>
    <br />
    <div class="e-footer-content" style="text-align: right; width: 100%;">
        <div class="button-container">
            <button type="submit" class="e-btn e-normal e-primary">Save</button>
            <button type="button" class="e-btn e-normal" @onclick="@Cancel">Cancel</button>
        </div>
    </div>
</EditForm>

<SfDialog @ref="DialogAddEditOrderLine" IsModal="true" Width="600px" ShowCloseIcon="true" Visible="false">
    <DialogTemplates>
        <Header> @dialogHeaderText </Header>
    </DialogTemplates>
    <EditForm Model="@addeditOrderLine" OnValidSubmit="@OrderLineSave">
        <DataAnnotationsValidator />
        <div class=flex-container>
            <SfDropDownList DataSource="@product"
                            TItem="Product"
                            TValue="int"
                            Text="ProductID"
                            @bind-Value="addeditOrderLine.POLineProductID"
                            FloatLabelType="@FloatLabelType.Always"
                            Placeholder="Select a Product"
                            Enabled="true">
                <DropDownListTemplates TItem="Product">
                    <HeaderTemplate>
                        <span class='head'>
                            <span class='productcode'>Code</span>
                            <span class='description'>Description</span>
                        </span>
                    </HeaderTemplate>
                    <ItemTemplate Context="contextName">
                        <span class='item'>
                            <span class='productcode'>@((contextName as Product).ProductCode)</span>
                            <span class='description'>@((contextName as Product).ProductDescription)</span>
                        </span>
                    </ItemTemplate>
                </DropDownListTemplates>

                <DropDownListFieldSettings Text="ProductCode" Value="ProductID"></DropDownListFieldSettings>
                <DropDownListEvents TItem="Product" TValue="int" OnValueSelect="OnChangeProduct"></DropDownListEvents>
            </SfDropDownList>
        </div>
        <div class=flex-container>
            <SfTextBox Enabled="true" Placeholder="Product Description"
                       FloatLabelType="@FloatLabelType.Always"
                       @bind-Value="addeditOrderLine.POLineProductDescription"></SfTextBox>
        </div>
        <div class=flex-container>
            <ValidationMessage For="@(() => addeditOrderLine.POLineProductDescription)" />
        </div><div class=flex-container>
            <SfNumericTextBox Enabled="true" Placeholder="Quantity"
                              FloatLabelType="@FloatLabelType.Always"
                              ShowSpinButton="false"
                              Format="n0"
                              Decimals="0"
                              ValidateDecimalOnType="true"
                              CssClass="e-style"
                              @bind-Value="addeditOrderLine.POLineProductQuantity"
                              @onfocusout='@POLineCalc'>
            </SfNumericTextBox>

            <SfNumericTextBox Enabled="true" Placeholder="Unit Price"
                              FloatLabelType="@FloatLabelType.Always"
                              ShowSpinButton="false"
                              Format="c2"
                              Decimals="2"
                              ValidateDecimalOnType="true"
                              CssClass="e-style"
                              @bind-Value="addeditOrderLine.POLineProductUnitPrice"
                              @onfocusout='@POLineCalc'>
            </SfNumericTextBox>

            <SfNumericTextBox Enabled="false" Placeholder="Net Price"
                              FloatLabelType="@FloatLabelType.Always"
                              ShowSpinButton="false"
                              Format="c2"
                              EnableRtl="true"
                              @bind-Value="addeditOrderLine.POLineNetPrice">
            </SfNumericTextBox>
        </div>
        <div class=flex-container>
            <SfDropDownList DataSource="@tax"
                            TItem="Tax"
                            TValue="int"
                            Text="TaxID"
                            @bind-Value="addeditOrderLine.POLineTaxID"
                            FloatLabelType="@FloatLabelType.Always"
                            Placeholder="Tax Rate"
                            Enabled="true">
                <DropDownListFieldSettings Text="TaxDescription" Value="TaxID"></DropDownListFieldSettings>
                <DropDownListEvents TItem="Tax" TValue="int" OnValueSelect="OnChangeTax"></DropDownListEvents>
            </SfDropDownList>

            <SfNumericTextBox Enabled="false" Placeholder="Tax Rate %"
                              FloatLabelType="@FloatLabelType.Always"
                              ShowSpinButton="false"
                              Format="p2"
                              EnableRtl="true"
                              @bind-Value="addeditOrderLine.POLineTaxRate">
            </SfNumericTextBox>

            <SfNumericTextBox Enabled="false" Placeholder="Tax Amount"
                              FloatLabelType="@FloatLabelType.Always"
                              ShowSpinButton="false"
                              Format="c2"
                              EnableRtl="true"
                              @bind-Value="addeditOrderLine.POLineTaxAmount">
            </SfNumericTextBox>
        </div>
        <div class=flex-container>
            <SfNumericTextBox Enabled="false" Placeholder="Total Price"
                              FloatLabelType="@FloatLabelType.Always"
                              ShowSpinButton="false"
                              Format="c2"
                              EnableRtl="true"
                              @bind-Value="addeditOrderLine.POLineGrossPrice">
            </SfNumericTextBox>
        </div>

        <br />
        <div class="e-footer-content">
            <div class="button-container">
                <button type="submit" class="e-btn e-normal e-primary">Save</button>
                <button type="button" class="e-btn e-normal" @onclick="@CloseDialog">Cancel</button>
            </div>
        </div>
    </EditForm>
</SfDialog>

<ConfirmPage @ref="ConfirmDeletion" ConfirmHeaderMessage="@ConfirmHeaderMessage" ConfirmContentMessage="@ConfirmContentMessage" ConfirmationChanged="ConfirmDelete" />

<WarningPage @ref="Warning" WarningHeaderMessage="@WarningHeaderMessage" WarningContentMessage="@WarningContentMessage" />

<ConfirmPage @ref="ConfirmSaveOrder" ConfirmHeaderMessage="@ConfirmHeaderMessage" ConfirmContentMessage="@ConfirmContentMessage" ConfirmationChanged="OrderSaveProcess" />

<style>
    .grid-container {
        display: grid;
        max-width: 900px; /* Maximum width of the whole container - in this case both columns */
        grid-template-columns: 1fr 1fr; /* Relative width of each column (1fr 1fr is equivalent to, say, 33fr 33fr */
        grid-gap: 75px; /* size of the gap between columns */
    }

    .flex-container {
        display: flex;
        flex-direction: row; /* Causes tab to move along row and then onto following row */
        justify-content: space-evenly; /* Equal space left and right margin and between elements */
        margin: 10px; /* This appears to be vertical margin between rows */
        column-gap: 10px; /* Tgap betwen columns */
    }

    .e-numeric.e-style .e-control.e-numerictextbox {
        text-align: right;
        padding: 0px 5px 0px 0px;
    }

    .head, .item {
        display: table;
        width: 100%;
        margin: auto;
        text-align: left;
    }

    .head {
        height: 30px;
        font-size: 15px;
        font-weight: 600;
    }

    .productcode {
        display: table-cell;
        vertical-align: middle;
        text-align: left;
        width: 25%;
    }

    .description {
        display: table-cell;
        vertical-align: middle;
        text-align: left;
        width: 75%;
    }

    .head .productcode {
        text-indent: 17px;
    }

    .head .description {
        text-indent: 14px;
    }
</style>


@code {
    POHeader orderaddedit = new POHeader();
    IEnumerable<Supplier> supplier;
    IEnumerable<Product> product;
    IEnumerable<Tax> tax;
    IEnumerable<POLine> orderLinesByPOHeader;

    string pagetitle = "";
    string dialogHeaderText = "";

    private string UserName;

    SfGrid<POLine> OrderLinesGrid;
    public List<POLine> orderLines = new List<POLine>();
    private List<ItemModel> Toolbaritems = new List<ItemModel>();

    private List<int> OrderLinesToBeDeleted = new List<int>();

    SfDialog DialogAddEditOrderLine;

    public POLine addeditOrderLine = new POLine();

    WarningPage Warning;
    string WarningHeaderMessage = "";
    string WarningContentMessage = "";

    ConfirmPage ConfirmDeletion;
    ConfirmPage ConfirmSaveOrder;
    string ConfirmHeaderMessage = "";
    string ConfirmContentMessage = "";
    public bool ConfirmationChanged { get; set; } = false;

    public bool supplierEnabled { get; set; } = true;

    private int tmpPOLineID { get; set; } = 0;
    private int selectedPOLineID { get; set; } = 0;

    private int POHeaderID { get; set; } = 0;

    [Parameter]
    public Guid POHeaderGuid { get; set; }

    //Executes on page open, sets headings and gets data in the case of edit
    protected override async Task OnInitializedAsync()
    {
        supplier = await SupplierService.SupplierList();
        orderaddedit.POHeaderOrderDate = DateTime.Now;
        tax = await TaxService.TaxList();

        if (POHeaderGuid == Guid.Empty)
        {
            pagetitle = "Add an Order";

            //Get user if logged in and populate the 'Requested by' column
            var authState = await AuthenticationStateProvider.GetAuthenticationStateAsync();
            var user = authState.User;

            if (user.Identity.IsAuthenticated)
            {
                UserName = user.Identity.Name;
            }
            else
            {
                UserName = "The user is NOT authenticated.";
            }

            orderaddedit.POHeaderRequestedBy = UserName;

        }
        else
        {
            pagetitle = "Edit an Order";
            orderaddedit = await POHeaderService.POHeader_GetOneByGuid(POHeaderGuid);
            POHeaderID = orderaddedit.POHeaderID;
            orderLinesByPOHeader = await POLineService.POLine_GetByPOHeader(POHeaderID);
            orderLines = orderLinesByPOHeader.ToList(); //Convert from IEnumable to List
            supplierEnabled = false;
        }

        Toolbaritems.Add(new ItemModel() { Text = "Add", TooltipText = "Add a new order line", PrefixIcon = "e-add" });
        Toolbaritems.Add(new ItemModel() { Text = "Edit", TooltipText = "Edit selected order line", PrefixIcon = "e-edit" });
        Toolbaritems.Add(new ItemModel() { Text = "Delete", TooltipText = "Delete selected order line", PrefixIcon = "e-delete" });

    }

    private void OnChangeSupplier(Syncfusion.Blazor.DropDowns.ChangeEventArgs<int, Supplier> args)
    {
        this.orderaddedit.POHeaderSupplierAddress1 = args.ItemData.SupplierAddress1;
        this.orderaddedit.POHeaderSupplierAddress2 = args.ItemData.SupplierAddress2;
        this.orderaddedit.POHeaderSupplierAddress3 = args.ItemData.SupplierAddress3;
        this.orderaddedit.POHeaderSupplierPostCode = args.ItemData.SupplierPostCode;
        this.orderaddedit.POHeaderSupplierEmail = args.ItemData.SupplierEmail;
    }

    // Executes OnValidSubmit of EditForm above
    protected async Task OrderSave()
    {
        if (orderaddedit.POHeaderSupplierID == 0)
        {
            WarningHeaderMessage = "Warning!";
            WarningContentMessage = "Please Select a Supplier before saving the order.";
            Warning.OpenDialog();
            return;
        }

        if (orderLines.Count == 0)
        {
            ConfirmHeaderMessage = "Confirm Save!";
            ConfirmContentMessage = "There are no order lines. Please confirm order should be saved.";
            ConfirmSaveOrder.OpenDialog();
        }
        else
        {
            await OrderSaveProcess(true);
        }

    }

    //Executes if user clicks the Cancel button.
    void Cancel()
    {
        NavigationManager.NavigateTo("/");
    }

    public async Task ToolbarClickHandler(Syncfusion.Blazor.Navigations.ClickEventArgs args)
    {

        //Refresh product to select only those products for this supplier (and products with null suppliers)
        product = await ProductService.ProductListBySupplier(orderaddedit.POHeaderSupplierID);

        if (args.Item.Text == "Add")
        {
            //Code for adding goes here
            dialogHeaderText = "Add an Order Line";
            //Check that a supplier has been selected from the drop-down list
            if (orderaddedit.POHeaderSupplierID == 0)
            {
                WarningHeaderMessage = "Warning!";
                WarningContentMessage = "Please Select a Supplier before adding order lines.";
                Warning.OpenDialog();
            }
            else
            {
                addeditOrderLine = new POLine();          // Ensures a blank form when adding
                addeditOrderLine.POLineNetPrice = 0;
                addeditOrderLine.POLineTaxID = 0;
                addeditOrderLine.POLineProductID = 0;
                await this.DialogAddEditOrderLine.Show();
            }

        }

        if (args.Item.Text == "Edit")
        {
            dialogHeaderText = "Edit an Order Line";
            //Check that an order line has been selected
            if (selectedPOLineID == 0)
            {
                WarningHeaderMessage = "Warning!";
                WarningContentMessage = "Please select an Order Line from the grid.";
                Warning.OpenDialog();
            }
            else
            {
                //populate addeditOrderLine (temporary data set used for the editing process)
                addeditOrderLine = orderLines.Where(x => x.POLineID == selectedPOLineID).FirstOrDefault();
                StateHasChanged();
                await this.DialogAddEditOrderLine.Show();
            }
        }

        if (args.Item.Text == "Delete")
        {
            //Code for adding goes here
            if (selectedPOLineID == 0)
            {
                WarningHeaderMessage = "Warning!";
                WarningContentMessage = "Please select an Order Line from the grid.";
                Warning.OpenDialog();
            }
            else
            {
                ConfirmHeaderMessage = "Confirm Deletion";
                ConfirmContentMessage = "Please confirm that this order line should be deleted.";
                ConfirmDeletion.OpenDialog();
            }
        }
    }

    private async Task OrderLineSave()
    {
        if (addeditOrderLine.POLineID == 0)
        {
            //Code to save new order line goes here
            //Check that a product has been selected from the drop-down list
            if (addeditOrderLine.POLineProductCode == null || addeditOrderLine.POLineProductCode == "")
            {
                WarningHeaderMessage = "Warning!";
                WarningContentMessage = "Please select a Product.";
                Warning.OpenDialog();
            }
            //And check that a tax rate has been selected from the drop-down list
            else if (addeditOrderLine.POLineTaxID == 0)
            {
                WarningHeaderMessage = "Warning!";
                WarningContentMessage = "Please select a Tax Rate.";
                Warning.OpenDialog();
            }
            else
            {
                POLineCalc();
                tmpPOLineID = tmpPOLineID - 1;        //used to provide a temporary ID for POLineID

                orderLines.Add(new POLine
                {
                    POLineID = tmpPOLineID,
                    POLineHeaderID = 0,
                    POLineProductID = addeditOrderLine.POLineProductID,
                    POLineProductCode = addeditOrderLine.POLineProductCode,
                    POLineProductDescription = addeditOrderLine.POLineProductDescription,
                    POLineProductQuantity = addeditOrderLine.POLineProductQuantity,
                    POLineProductUnitPrice = addeditOrderLine.POLineProductUnitPrice,
                    POLineNetPrice = addeditOrderLine.POLineNetPrice,
                    POLineTaxRate = addeditOrderLine.POLineTaxRate,
                    POLineTaxAmount = addeditOrderLine.POLineTaxAmount,
                    POLineGrossPrice = addeditOrderLine.POLineGrossPrice,
                    POLineTaxID = addeditOrderLine.POLineTaxID
                });


                OrderLinesGrid.Refresh();
                StateHasChanged();                  //<-----  THIS IS ABSOLUTELY ESSENTIAL

                //addeditOrderLine = new POLine();  //<-----  THIS gives errors (nulls)

                addeditOrderLine.POLineProductID = 0;
                addeditOrderLine.POLineProductCode = "";
                addeditOrderLine.POLineProductDescription = "";
                addeditOrderLine.POLineProductQuantity = 0;
                addeditOrderLine.POLineProductUnitPrice = 0;
                addeditOrderLine.POLineNetPrice = 0;
                //addeditOrderLine.POLineTaxID = 0;                 //Leave - highly likely to be same as previous record
                //addeditOrderLine.POLineTaxRate = 0;               //Leave - highly likely to be same as previous record
                addeditOrderLine.POLineTaxAmount = 0;
                addeditOrderLine.POLineGrossPrice = 0;

                //We now have order lines, so prevent user from changing the supplier
                supplierEnabled = false;
            }
        }

        else
        //An order line is being edited
        //Check that a product has been selected from the drop-down list
        if (addeditOrderLine.POLineProductCode == null || addeditOrderLine.POLineProductCode == "")
        {
            WarningHeaderMessage = "Warning!";
            WarningContentMessage = "Please select a Product.";
            Warning.OpenDialog();
        }
        //And check that a tax rate has been selected from the drop-down list
        else if (addeditOrderLine.POLineTaxID == 0)
        {
            WarningHeaderMessage = "Warning!";
            WarningContentMessage = "Please select a Tax Rate.";
            Warning.OpenDialog();
        }
        else
        {
            OrderLinesGrid.Refresh();
            StateHasChanged();                  //<-----  THIS IS ABSOLUTELY ESSENTIAL
            await CloseDialog();                //No need to keep dialog open
        }
    }


    private async Task CloseDialog()
    {
        await this.DialogAddEditOrderLine.Hide();
    }

    private void OnChangeProduct(Syncfusion.Blazor.DropDowns.SelectEventArgs<Product> args)
    {
        this.addeditOrderLine.POLineProductCode = args.ItemData.ProductCode;
        this.addeditOrderLine.POLineProductDescription = args.ItemData.ProductDescription;
        this.addeditOrderLine.POLineProductUnitPrice = args.ItemData.ProductUnitPrice;
        POLineCalc();
    }

    private void OnChangeTax(Syncfusion.Blazor.DropDowns.SelectEventArgs<Tax> args)
    {
        // int testTaxId = args.ItemData.TaxID;
        this.addeditOrderLine.POLineTaxRate = args.ItemData.TaxRate;
        POLineCalc();
    }

    private void POLineCalc()
    {
        addeditOrderLine.POLineNetPrice = addeditOrderLine.POLineProductUnitPrice * addeditOrderLine.POLineProductQuantity;
        addeditOrderLine.POLineTaxAmount = addeditOrderLine.POLineNetPrice.Value * addeditOrderLine.POLineTaxRate;
        addeditOrderLine.POLineGrossPrice = addeditOrderLine.POLineNetPrice.Value * (1 + addeditOrderLine.POLineTaxRate);
    }

    public void RowSelectHandler(RowSelectEventArgs<POLine> args)
    {
        //{args.Data} returns the current selected records.
        selectedPOLineID = args.Data.POLineID;
    }

    private void OrderLineDelete()
    {
        if (selectedPOLineID > 0)
        {
            //Order line has already been saved to the database, and was present at start of this order edit
            //Add to list of orders to be deleted when order is saved
            OrderLinesToBeDeleted.Add(selectedPOLineID);
        }

        //And then delete from orderLines

        var itemToRemove = orderLines.Single(x => x.POLineID == selectedPOLineID);
        orderLines.Remove(itemToRemove);
        OrderLinesGrid.Refresh();
    }

    protected void ConfirmDelete(bool deleteConfirmed)
    {
        if (deleteConfirmed)
        {
            OrderLineDelete();
            StateHasChanged();
            selectedPOLineID = 0;
        }
    }

    protected async Task OrderSaveProcess(bool saveConfirmed)
    {
        if (saveConfirmed)
        {
            if (POHeaderID == 0)
            {
                //Save the record - 1st - the POHeader

                int HeaderID = await POHeaderService.POHeaderInsert(
                               orderaddedit.POHeaderOrderDate,
                               orderaddedit.POHeaderSupplierID,
                               orderaddedit.POHeaderSupplierAddress1,
                               orderaddedit.POHeaderSupplierAddress2,
                               orderaddedit.POHeaderSupplierAddress3,
                               orderaddedit.POHeaderSupplierPostCode,
                               orderaddedit.POHeaderSupplierEmail,
                               orderaddedit.POHeaderRequestedBy
                               );

                //2nd - the POLines
                foreach (var individualPOLine in orderLines)
                {
                    individualPOLine.POLineHeaderID = HeaderID;
                    bool Success = await POLineService.POLineInsert(individualPOLine);
                }

                NavigationManager.NavigateTo("/");
            }
            else
            {
                //Order is being edited
                //POHeader
                bool Success = await POHeaderService.POHeaderUpdate(orderaddedit);

                //POLines
                foreach (var individualPOLine in orderLines)
                {
                    //If POLineHeaderID is positive it means it has been edited during the edit of this order
                    if (individualPOLine.POLineID > 0)
                    {
                        Success = await POLineService.POLineUpdate(individualPOLine);
                    }
                    else
                    //If POLineID is negative it means it has been added during the edit of this order
                    {
                        individualPOLine.POLineHeaderID = POHeaderID;
                        Success = await POLineService.POLineInsert(individualPOLine);
                    }
                }

                foreach (var individualPOLine in OrderLinesToBeDeleted)
                {
                    Success = await POLineService.POLineDeleteOne(individualPOLine);
                }
                //Clear the list of POLines to be deleted
                OrderLinesToBeDeleted.Clear();

                NavigationManager.NavigateTo("/");
            }
        }
    }
}