SelectNode.FilterString Property

Specifies the criteria used to filter data returned by the node.

Namespace: DevExpress.DataAccess.DataFederation

Assembly: DevExpress.DataAccess.v19.1.dll

Declaration

C#

[DefaultValue(null)]
public string FilterString { get; set; }

VB.NET

<DefaultValue(Nothing)>
Public Property FilterString As String

Property Value

Type	Default	Description
String	*null*	A string that is the filter criteria.

Remarks

The FilterString property allows you to apply a filter to the data returned by the SelectNode.

The following example filters the Orders table by the Seafood category. The CategoryName value is defined as a parameter cat - the ? sign precedes the parameter name. The parameter value is specified in the FederationDataSource.Fill(String[]) method call.

Example

This code snippet demonstrates how to create a federated data source that uses a filter with a parameter.

Note

The complete sample project How to Create a Federated Data Source at Runtime is available in the DevExpress Examples repository.

C#

using DevExpress.DataAccess.DataFederation;
// ...
    FederationDataSource federation = new FederationDataSource();

    Source source = new Source("excelSource", CreateExcelDataSource("SalesPerson.xlsx", "Data"));

    var sourceNode = new SourceNode(source, "Orders");

    var query = new SelectNode(sourceNode)
    {
        Alias = "excel",
        Expressions = {
                new SelectColumnExpression(sourceNode, "OrderID"),
                new SelectColumnExpression(sourceNode, "OrderDate"),
                new SelectColumnExpression(sourceNode, "Sales Person"),
                new SelectColumnExpression(sourceNode, "ProductName"),
                new SelectColumnExpression(sourceNode, "Extended Price")
            },
        FilterString = "[Orders.CategoryName] = ?cat",
    };
    federation.Queries.Add(query);
    federation.Fill(new[] { 
        new DevExpress.DataAccess.Sql.QueryParameter("cat", typeof(string), "Seafood") });

VB.NET

Imports DevExpress.DataAccess.DataFederation
' ... 
    Dim federation As New FederationDataSource()

    Dim source As New Source("excelSource", CreateExcelDataSource("SalesPerson.xlsx", "Data"))

    Dim sourceNode = New SourceNode(source, "Orders")

    Dim query = New SelectNode(sourceNode)
    query.Alias = "excel"
    query.Expressions.Add(New SelectColumnExpression(sourceNode, "OrderID"))
    query.Expressions.Add(New SelectColumnExpression(sourceNode, "OrderDate"))
    query.Expressions.Add(New SelectColumnExpression(sourceNode, "Sales Person"))
    query.Expressions.Add(New SelectColumnExpression(sourceNode, "ProductName"))
    query.Expressions.Add(New SelectColumnExpression(sourceNode, "Extended Price"))
    query.FilterString = "[Orders.CategoryName] = ?cat"
    federation.Queries.Add(query)
    federation.Fill( { 
        New DevExpress.DataAccess.Sql.QueryParameter("cat", GetType(String), "Seafood") })

Related GitHub Examples

The following code snippet (auto-collected from DevExpress Examples) contains a reference to the FilterString property.

Note

The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.

VB.NET

how-to-create-a-federated-data-source-at-runtime/VB/FederationDataSourceExample/FederationDataSourceHelper.vb#L26

query.Expressions.Add(New SelectColumnExpression(sourceNode, "Extended Price"))
query.FilterString = "[Orders.CategoryName] = ?cat"
federation.Queries.Add(query)