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

NuGet Packages: DevExpress.DataAccess, DevExpress.WindowsDesktop.DataAccess

Declaration

C#

public Task FillAsync(
    IEnumerable<IParameter> sourceParameters
)

VB.NET

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.

C#

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) });

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
' ...
' Create and configure an SQL data source.
Private sqlDataSource As New SqlDataSource(New Access97ConnectionParameters(Path.Combine(Path.GetDirectoryName(GetType(ReportCreator).Assembly.Location), "Data/nwind.mdb"), "", "")) With {.Name = "Sql_Categories"}
Private 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", GetType(Expression), New Expression("?CategoryID")))
sqlDataSource.Queries.Add(categoriesQuery)
sqlDataSource.RebuildResultSchema()

' Create and configure an Excel data source.
Dim excelDataSource As New ExcelDataSource() With {.Name = "Excel_Products"}
excelDataSource.FileName = Path.Combine(Path.GetDirectoryName(GetType(Form1).Assembly.Location), "Data/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(excelDataSource, "[Excel_Products.CategoryID] = [Sql_Categories.CategoryID]").Select("CategoryID", "ProductName", "UnitPrice").Build("CategoriesProducts")

Dim ordersQuery As SelectNode = 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 Parameter("CategoryID", GetType(System.Int32), 4) })