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DxGrid.WaitForRemoteSourceRowLoadAsync(Int32) Method

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DxGrid.WaitForRemoteSourceRowLoadAsync(Int32) Method

Returns a task that is completed when the specified row of an asynchronous remote data source is loaded.

Namespace : DevExpress.Blazor

Assembly : DevExpress.Blazor.v25.2.dll

NuGet Package : DevExpress.Blazor

Declaration

csharp
public Task WaitForRemoteSourceRowLoadAsync(
    int visibleIndex
)

Parameters

NameTypeDescription
visibleIndexInt32

The row’s visible index.

|

Returns

TypeDescription
Task

The task that is completed when the row is loaded.

|

Remarks

The following data sources are designed to work with large data collections:

They load data asynchronously in small portions on demand (instead of the entire dataset).

Call the WaitForRemoteSourceRowLoadAsync method to ensure that the specified data row is loaded. For instance, call this method before those that accept a row’s visible index as a parameter (SelectRow, StartEditRowAsync, and so on).

For multiple rows, use the await Task.WhenAll(…) statement to combine multiple WaitForRemoteSourceRowLoadAsync method calls.

The following example selects a row that is outside the visible range and not yet loaded:

razor
@using Microsoft.EntityFrameworkCore
@using DevExpress.Data.Linq
@inject IDbContextFactory<NorthwindContext> NorthwindContextFactory
@implements IDisposable

<DxGrid Data="InstantFeedbackSource"
        AllowSelectRowByClick="true"
        KeyFieldName="OrderId"
        @ref="MyGrid"> 
    <Columns>
        <DxGridDataColumn FieldName="ShipName" />
        <DxGridDataColumn FieldName="ShipCity" />
        <DxGridDataColumn FieldName="ShipCountry" />
        <DxGridDataColumn FieldName="Freight" />
        <DxGridDataColumn FieldName="OrderDate" />
        <DxGridDataColumn FieldName="ShippedDate" />
    </Columns>
</DxGrid>

<DxButton Click="OnSelectRow">Select Row 100</DxButton>

@code {
    EntityInstantFeedbackSource InstantFeedbackSource { get; set; }
    NorthwindContext Northwind { get; set; }
    IGrid MyGrid { get; set; }

    protected override void OnInitialized() {
        Northwind = NorthwindContextFactory.CreateDbContext();
        InstantFeedbackSource = new EntityInstantFeedbackSource(e => {
            e.KeyExpression = "OrderId";
            e.QueryableSource = Northwind.Orders;
        });
    }

    public async Task OnSelectRow() {
        await MyGrid.WaitForRemoteSourceRowLoadAsync(100);
        MyGrid.SelectRow(100);
    }

    public void Dispose() {
        InstantFeedbackSource?.Dispose();
        Northwind?.Dispose();
    }
}
csharp
using System;
using System.Collections.Generic;

#nullable disable

namespace Grid.Northwind {
    public partial class Order {
        public Order() {
            OrderDetails = new HashSet<OrderDetail>();
        }

        public int OrderId { get; set; }
        public string CustomerId { get; set; }
        public int? EmployeeId { get; set; }
        public DateTime? OrderDate { get; set; }
        public DateTime? RequiredDate { get; set; }
        public DateTime? ShippedDate { get; set; }
        public int? ShipVia { get; set; }
        public decimal? Freight { get; set; }
        public string ShipName { get; set; }
        public string ShipAddress { get; set; }
        public string ShipCity { get; set; }
        public string ShipRegion { get; set; }
        public string ShipPostalCode { get; set; }
        public string ShipCountry { get; set; }

        public virtual Customer Customer { get; set; }
        public virtual Shipper ShipViaNavigation { get; set; }
        public virtual ICollection<OrderDetail> OrderDetails { get; set; }
    }
}
csharp
using Microsoft.EntityFrameworkCore;
#nullable disable

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

        public NorthwindContext(DbContextOptions<NorthwindContext> options)
            : base(options) {
        }
        // ...
        public virtual DbSet<Order> Orders { 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<Order>(entity => {
                entity.HasIndex(e => e.CustomerId, "CustomerID");
                entity.HasIndex(e => e.CustomerId, "CustomersOrders");
                entity.HasIndex(e => e.EmployeeId, "EmployeeID");
                entity.HasIndex(e => e.EmployeeId, "EmployeesOrders");
                entity.HasIndex(e => e.OrderDate, "OrderDate");
                entity.HasIndex(e => e.ShipPostalCode, "ShipPostalCode");
                entity.HasIndex(e => e.ShippedDate, "ShippedDate");
                entity.HasIndex(e => e.ShipVia, "ShippersOrders");
                entity.Property(e => e.OrderId).HasColumnName("OrderID");
                entity.Property(e => e.CustomerId)
                    .HasMaxLength(5)
                    .HasColumnName("CustomerID")
                    .IsFixedLength(true);
                entity.Property(e => e.EmployeeId).HasColumnName("EmployeeID");
                entity.Property(e => e.Freight)
                    .HasColumnType("money")
                    .HasDefaultValueSql("((0))");
                entity.Property(e => e.OrderDate).HasColumnType("datetime");
                entity.Property(e => e.RequiredDate).HasColumnType("datetime");
                entity.Property(e => e.ShipAddress).HasMaxLength(60);
                entity.Property(e => e.ShipCity).HasMaxLength(15);
                entity.Property(e => e.ShipCountry).HasMaxLength(15);
                entity.Property(e => e.ShipName).HasMaxLength(40);
                entity.Property(e => e.ShipPostalCode).HasMaxLength(10);
                entity.Property(e => e.ShipRegion).HasMaxLength(15);
                entity.Property(e => e.ShippedDate).HasColumnType("datetime");
                entity.HasOne(d => d.Customer)
                    .WithMany(p => p.Orders)
                    .HasForeignKey(d => d.CustomerId)
                    .HasConstraintName("FK_Orders_Customers");
                entity.HasOne(d => d.ShipViaNavigation)
                    .WithMany(p => p.Orders)
                    .HasForeignKey(d => d.ShipVia)
                    .HasConstraintName("FK_Orders_Shippers");
            });
            // ...
            OnModelCreatingPartial(modelBuilder);
        }

        partial void OnModelCreatingPartial(ModelBuilder modelBuilder);
    }
}
csharp
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);
});

Implements

WaitForRemoteSourceRowLoadAsync(Int32)

See Also

DxGrid Class

DxGrid Members

DevExpress.Blazor Namespace