FederationDataSource.FillAsync() Method
Populates the FederationDataSource in an asynchronous manner.
Namespace: DevExpress.DataAccess.DataFederation
Assembly: DevExpress.DataAccess.v20.2.dll
NuGet Packages: DevExpress.DataAccess, DevExpress.WindowsDesktop.DataAccess
Declaration
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.
using System.Threading;
using System.Threading.Tasks;
using DevExpress.DataAccess;
using DevExpress.DataAccess.Sql;
using DevExpress.DataAccess.Excel;
using DevExpress.DataAccess.DataFederation;
using DevExpress.DataAccess.ObjectBinding;
using DevExpress.DataAccess.ConnectionParameters;
// ...
// Create and configure 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()
.Build("Categories");
sqlDataSource.Queries.Add(categoriesQuery);
sqlDataSource.RebuildResultSchema();
// Create and configure an Excel data source.
ExcelDataSource excelDataSource = new ExcelDataSource() { Name = "Excel_Products" };
excelDataSource.FileName = Path.Combine(Path.GetDirectoryName(typeof(Form1).Assembly.Location), "Data/Products.xlsx");
excelDataSource.SourceOptions = new ExcelSourceOptions() {
ImportSettings = new ExcelWorksheetSettings("Sheet"),
};
excelDataSource.RebuildResultSchema();
// Create and configure 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(excelDataSource, "[Excel_Products.CategoryID] = [Sql_Categories.CategoryID]")
.Select("CategoryID", "ProductName", "UnitPrice")
.Build("CategoriesProducts");
SelectNode ordersQuery = sourceHeader.From().Select("OrderID", "Status", "Description")
.Join(sourceOrderDetail, "[OrderHeader.OrderID] = [OrderDetail.OrderID]")
.Select("Quantity", "Extended Price")
.Build("OrderHeaderOrderDetail");
federationDataSource.Queries.Add(selectNode);
// Populate the data source.
await federationDataSource.FillAsync();