All docs
V20.2
20.2
20.1
19.2
19.1
The page you are viewing does not exist in version 19.1. This link will take you to the root page.
18.2
The page you are viewing does not exist in version 18.2. This link will take you to the root page.
18.1
The page you are viewing does not exist in version 18.1. This link will take you to the root page.
17.2
The page you are viewing does not exist in version 17.2. This link will take you to the root page.

FederationDataSource.FillAsync(IEnumerable<IParameter>) Method

Populates the FederationDataSource in an asynchronous manner and passes external parameters to the data source.

Namespace: DevExpress.DataAccess.DataFederation

Assembly: DevExpress.DataAccess.v20.2.dll

Declaration

public Task FillAsync(
    IEnumerable<IParameter> sourceParameters
)
Public Function FillAsync(
    sourceParameters As IEnumerable(Of IParameter)
) As Task

Parameters

Name Type Description
sourceParameters IEnumerable<IParameter>

External parameters passed to the data source.

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.

The sourceParameters parameter passes a collection of external parameters to the data source. For instance, you can pass report parameters from a reporting application and use report parameter values to filter data in the inner data sources.

Example

The code sample below creates a federated data source and binds the SQL data source query's Category parameter to the CategoryID external parameter. A CancellationTokenSource class instance is used to allow users to interrupt the data source fill process if it takes too long.

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()
    .Filter("CategoryID=?Category")
    .Build("Categories");
// Bind the "Category" query parameter to the "CategoryID" external parameter.
categoriesQuery.Parameters.Add(new QueryParameter("Category", typeof(Expression), new Expression("?CategoryID")));
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 and pass a parameter.
await federationDataSource.FillAsync(new[] { new Parameter("CategoryID", typeof(System.Int32), 4) });
See Also