DxGrid.EditStart Event

Fires before the Grid starts editing a row.

Namespace: DevExpress.Blazor

Assembly: DevExpress.Blazor.v24.2.dll

NuGet Package: DevExpress.Blazor

Declaration

[Parameter]
public EventCallback<GridEditStartEventArgs> EditStart { get; set; }

Parameters

Type	Description
GridEditStartEventArgs	An object that contains data for this event.

Remarks

The EditStart event occurs in the following cases:

• A user clicks the New or Edit button in the command column.
• A user clicks the new item row or focuses it and presses Enter.
• In EditCell mode, a user clicks a data cell in a row that is in display mode or focuses this cell and presses Enter.
• The StartEditRowAsync, StartEditDataItemAsync, or StartEditNewRowAsync method is called.

Handle this event to create a custom response to the edit start action. Use the IsNew event argument to identify whether a new or existing data item is about to be edited. The DataItem property returns the processed data item. The Grid property allows you access the Grid and its extensive API.

You can set the Cancel event argument to true to prevent users from editing specific rows. The following code snippet prevents users from editing unselected rows:

Razor

@using Microsoft.EntityFrameworkCore
@inject IDbContextFactory<NorthwindContext> NorthwindContextFactory
@implements IDisposable

<DxGrid Data="GridDataSource"
        EditModelSaving="OnEditModelSaving"
        KeyFieldName="EmployeeId"
        AllowSelectRowByClick="true"
        SelectionMode="GridSelectionMode.Single"
        @bind-SelectedDataItem="@SelectedDataItem"
        EditStart="OnEditStart"
        EditMode="GridEditMode.EditRow">
    <Columns>
        <DxGridCommandColumn DeleteButtonVisible="false" />
        <DxGridDataColumn FieldName="FirstName" />
        <DxGridDataColumn FieldName="LastName" />
        <DxGridDataColumn FieldName="Title" />
        <DxGridDataColumn FieldName="HireDate" />
    </Columns>
</DxGrid>

@code {
    IEnumerable<object> GridDataSource { get; set; }
    NorthwindContext Northwind { get; set; }
    object SelectedDataItem { get; set; }

    protected override async Task OnInitializedAsync() {
        Northwind = NorthwindContextFactory.CreateDbContext();
        GridDataSource = await Northwind.Employees.ToListAsync();
        SelectedDataItem = GridDataSource.FirstOrDefault();
    }

    async Task OnEditModelSaving(GridEditModelSavingEventArgs e) {
        var editModel = (Employee)e.EditModel;
        // Assign changes from the edit model to the data item.
        if (e.IsNew)
            await Northwind.AddAsync(editModel);
        else
            e.CopyChangesToDataItem();
        // Post changes to the database.
        await Northwind.SaveChangesAsync();
        // Reload the entire Grid.
        GridDataSource = await Northwind.Employees.ToListAsync();
     }

    async Task OnEditStart(GridEditStartEventArgs e) {
        if (!e.IsNew && !e.Grid.IsDataItemSelected(e.DataItem))
            e.Cancel = true;
    }

    public void Dispose() {
        Northwind?.Dispose();
    }
}

Employee

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;

namespace Grid.Northwind {
    public partial class Employee {
        public int EmployeeId { get; set; }
        [Required]
        public string LastName { get; set; }
        [Required]
        public string FirstName { get; set; }
        [Required]
        public string Title { get; set; }
        public string TitleOfCourtesy { get; set; }
        public Nullable<System.DateTime> BirthDate { get; set; }
        [Required]
        [Range(typeof(DateTime), "1/1/2000", "1/1/2020",
        ErrorMessage = "HireDate must be between {1:d} and {2:d}")]
        public Nullable<System.DateTime> HireDate { get; set; }
        public string Address { get; set; }
        public string City { get; set; }
        public string Region { get; set; }
        public string PostalCode { get; set; }
        public string Country { get; set; }
        public string HomePhone { get; set; }
        public string Extension { get; set; }
        public byte[] Photo { get; set; }
        public string Notes { get; set; }
        public Nullable<int> ReportsTo { get; set; }
        public string PhotoPath { get; set; }
        public virtual ICollection<Order> Orders { get; set; }
        public string Text => $"{FirstName} {LastName} ({Title})";
        public string ImageFileName => $"Employees/{EmployeeId}.jpg";
    }
}

NorthwindContext

using Microsoft.EntityFrameworkCore;
#nullable disable

namespace Grid.Northwind {
    public partial class NorthwindContext : DbContext {

        public NorthwindContext(DbContextOptions<NorthwindContext> options)
            : base(options) {
        }
        // ...
        public virtual DbSet<Employee> Employees { get; set; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder) {
            if(!optionsBuilder.IsConfigured) {
                optionsBuilder.UseSqlServer("Server=.\\sqlexpress;Database=Northwind;Integrated Security=true");
            }
        }

        protected override void OnModelCreating(ModelBuilder modelBuilder) {
            modelBuilder.HasAnnotation("Relational:Collation", "SQL_Latin1_General_CP1_CI_AS");
            // ...
            modelBuilder.Entity<Employee>(entity => {
                entity.HasIndex(e => e.EmployeeId, "EmployeeId");
                entity.HasIndex(e => e.LastName, "LastName");
                entity.HasIndex(e => e.FirstName, "FirstName");
                entity.HasIndex(e => e.Title, "Title");
                entity.HasIndex(e => e.BirthDate, "BirthDate");
                entity.HasIndex(e => e.HireDate, "HireDate");
                entity.HasIndex(e => e.Notes, "Notes");
            });
            OnModelCreatingPartial(modelBuilder);
        }

        partial void OnModelCreatingPartial(ModelBuilder modelBuilder);
    }
}

Program.cs

using Microsoft.EntityFrameworkCore;
// ...
builder.Services.AddDbContextFactory<NorthwindContext>((sp, options) => {
    var env = sp.GetRequiredService<IWebHostEnvironment>();
    var dbPath = Path.Combine(env.ContentRootPath, "Northwind-5e44b51f.mdf");
    options.UseSqlServer("Server=(localdb)\\MSSQLLocalDB;Integrated Security=true;AttachDbFileName=" + dbPath);
});

For information on how to enable data editing, refer to the following topic: Editing and Validation in Blazor Grid.