FederationDataSource.FillAsync() Method

Populates the FederationDataSource in an asynchronous manner.

Namespace: DevExpress.DataAccess.DataFederation

Assembly: DevExpress.DataAccess.v24.2.dll

Declaration

C#

public Task FillAsync()

VB.NET

Public Function FillAsync As Task

Returns

Type	Description
Task	A task that populates the data source.

Remarks

Use this method to populate a federated data source in an individual task asynchronously. Unlike the Fill() method call, FillAsync does not lock other actions performed concurrently. For instance, the user interface remains operational while the data source is populated.

Call the FillAsync method with the await operator.

Example

The code sample below creates a federated data source and populates it in an asynchronous manner.

C#

using DevExpress.DataAccess;
using DevExpress.DataAccess.Sql;
using DevExpress.DataAccess.Excel;
using DevExpress.DataAccess.DataFederation;
using DevExpress.DataAccess.ObjectBinding;
using DevExpress.DataAccess.ConnectionParameters;
using System.IO;
using System.Threading;
// Creates and configures an SQL data source.
SqlDataSource sqlDataSource = new SqlDataSource(
    new Access97ConnectionParameters(
        Path.Combine(Path.GetDirectoryName(typeof(ReportCreator).Assembly.Location),
        "Data/nwind.mdb"), "", ""))
{ Name = "Sql_Categories" };
var categoriesQuery = SelectQueryFluentBuilder
    .AddTable("Categories")
    .SelectAllColumnsFromTable()
    .Filter("CategoryID=?Category")
    .Build("Categories");
sqlDataSource.Queries.Add(categoriesQuery);
sqlDataSource.RebuildResultSchema();

// Creates and configures an Excel data source.
ExcelDataSource excelDataSource = new ExcelDataSource() { Name = "Excel_Products" };
excelDataSource.FileName = "Products.xlsx";
excelDataSource.SourceOptions = new ExcelSourceOptions()
{
    ImportSettings = new ExcelWorksheetSettings("Sheet"),
};
excelDataSource.RebuildResultSchema();

// Creates and configures a federated data source.
FederationDataSource federationDataSource = new FederationDataSource();

Source sourceCategories = new Source(sqlDataSource.Name, sqlDataSource, "Categories");
Source sourceProducts = new Source(excelDataSource.Name, excelDataSource, "Products");

SelectNode selectNode = sourceCategories.From().Select("CategoryName")
    .Join(sourceProducts, "[Excel_Products.CategoryID] = [Sql_Categories.CategoryID]")
    .Select("CategoryID", "ProductName", "UnitPrice")
    .Build("CategoriesProducts");

federationDataSource.Queries.Add(selectNode);
// Populates the data source's CategoriesProducts query.
await federationDataSource.FillAsync();

VB.NET

Imports System.Threading
Imports System.Threading.Tasks
Imports DevExpress.DataAccess
Imports DevExpress.DataAccess.Sql
Imports DevExpress.DataAccess.Excel
Imports DevExpress.DataAccess.DataFederation
Imports DevExpress.DataAccess.ObjectBinding
Imports DevExpress.DataAccess.ConnectionParameters
Imports System.IO
' Creates and configures an SQL data source.
Dim sqlDataSource As New SqlDataSource(
    New Access97ConnectionParameters(
    Path.Combine(
    Path.GetDirectoryName(GetType(ReportCreator).Assembly.Location), "Data/nwind.mdb"), "", "")) With {
        .Name = "Sql_Categories"}
Dim categoriesQuery = SelectQueryFluentBuilder.AddTable("Categories").
    SelectAllColumnsFromTable().
    Filter("CategoryID=?Category").
    Build("Categories")
sqlDataSource.Queries.Add(categoriesQuery)
sqlDataSource.RebuildResultSchema()

' Create and configure an Excel data source.
Dim excelDataSource As New ExcelDataSource() With {.Name = "Excel_Products"}
excelDataSource.FileName = "Products.xlsx"
excelDataSource.SourceOptions = New ExcelSourceOptions() With {
    .ImportSettings = New ExcelWorksheetSettings("Sheet")}
excelDataSource.RebuildResultSchema()

' Create and configure a federated data source.
Dim federationDataSource As New FederationDataSource()

Dim sourceCategories As New Source(sqlDataSource.Name, sqlDataSource, "Categories")
Dim sourceProducts As New Source(excelDataSource.Name, excelDataSource, "Products")

Dim selectNode As SelectNode = sourceCategories.
    From().
    Select("CategoryName").
    Join(sourceProducts, "[Excel_Products.CategoryID] = [Sql_Categories.CategoryID]").
    Select("CategoryID", "ProductName", "UnitPrice").
    Build("CategoriesProducts")

federationDataSource.Queries.Add(selectNode)
' Populate the data source's CategoriesProducts query.
Await federationDataSource.FillAsync()