QueryExtender Class

Enables data from a data source to be filtered without an explicit Where clause in the data source.

System.Object
  System.Web.UI.Control
    System.Web.UI.WebControls.QueryExtender

Namespace:  System.Web.UI.WebControls
Assembly:  System.Web.Extensions (in System.Web.Extensions.dll)

[ToolboxBitmapAttribute(typeof(QueryExtender), "QueryExtender.bmp")]
public class QueryExtender : Control
<asp:QueryExtender />

The QueryExtender type exposes the following members.

  NameDescription
Public methodQueryExtenderInitializes a new instance of the QueryExtender Class.
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  NameDescription
Protected propertyAdapterGets the browser-specific adapter for the control. (Inherited from Control.)
Public propertyAppRelativeTemplateSourceDirectoryGets or sets the application-relative virtual directory of the Page or UserControl object that contains this control. (Inherited from Control.)
Public propertyBindingContainerInfrastructure. Gets the control that contains this control's data binding. (Inherited from Control.)
Protected propertyChildControlsCreatedGets a value that indicates whether the server control's child controls have been created. (Inherited from Control.)
Public propertyClientIDGets the control ID for HTML markup that is generated by ASP.NET. (Inherited from Control.)
Public propertyClientIDModeGets or sets the algorithm that is used to generate the value of the ClientID property. (Inherited from Control.)
Protected propertyClientIDSeparatorGets a character value representing the separator character used in the ClientID property. (Inherited from Control.)
Protected propertyContextGets the HttpContext object associated with the server control for the current Web request. (Inherited from Control.)
Public propertyControlsGets a ControlCollection object that represents the child controls for a specified server control in the UI hierarchy. (Inherited from Control.)
Public propertyDataItemContainerGets a reference to the naming container if the naming container implements IDataItemContainer. (Inherited from Control.)
Public propertyDataKeysContainerGets a reference to the naming container if the naming container implements IDataKeysControl. (Inherited from Control.)
Public propertyDataSourceGets the data source control (IDataSource object) to use for the query.
Protected propertyDesignModeGets a value indicating whether a control is being used on a design surface. (Inherited from Control.)
Public propertyEnableThemingGets or sets a value indicating whether themes apply to this control. (Inherited from Control.)
Public propertyEnableViewStateGets or sets a value indicating whether the server control persists its view state, and the view state of any child controls it contains, to the requesting client. (Inherited from Control.)
Protected propertyEventsGets a list of event handler delegates for the control. This property is read-only. (Inherited from Control.)
Public propertyExpressionsGets the collection of expressions that are applied to the IDataSource control.
Protected propertyHasChildViewStateGets a value indicating whether the current server control's child controls have any saved view-state settings. (Inherited from Control.)
Public propertyIDGets or sets the programmatic identifier assigned to the server control. (Inherited from Control.)
Protected propertyIdSeparatorInfrastructure. Gets the character used to separate control identifiers. (Inherited from Control.)
Protected propertyIsChildControlStateClearedGets a value indicating whether controls contained within this control have control state. (Inherited from Control.)
Protected propertyIsTrackingViewStateGets a value that indicates whether the server control is saving changes to its view state. (Inherited from Control.)
Protected propertyIsViewStateEnabledGets a value indicating whether view state is enabled for this control. (Inherited from Control.)
Protected propertyLoadViewStateByIDGets a value indicating whether the control participates in loading its view state by ID instead of index. (Inherited from Control.)
Public propertyNamingContainerGets a reference to the server control's naming container, which creates a unique namespace for differentiating between server controls with the same Control.ID property value. (Inherited from Control.)
Public propertyPageGets a reference to the Page instance that contains the server control. (Inherited from Control.)
Public propertyParentGets a reference to the server control's parent control in the page control hierarchy. (Inherited from Control.)
Public propertyRenderingCompatibilityGets a value that specifies the ASP.NET version that rendered HTML will be compatible with. (Inherited from Control.)
Public propertySiteGets information about the container that hosts the current control when rendered on a design surface. (Inherited from Control.)
Public propertySkinIDGets or sets the skin to apply to the control. (Inherited from Control.)
Public propertyTargetControlIDGets or sets the ID of the IDataSource control to use for the query.
Public propertyTemplateControlGets or sets a reference to the template that contains this control. (Inherited from Control.)
Public propertyTemplateSourceDirectoryGets the virtual directory of the Page or UserControl that contains the current server control. (Inherited from Control.)
Public propertyUniqueIDGets the unique, hierarchically qualified identifier for the server control. (Inherited from Control.)
Public propertyValidateRequestModeGets or sets a value that indicates whether the control checks client input from the browser for potentially dangerous values. (Inherited from Control.)
Protected propertyViewStateGets a dictionary of state information that allows you to save and restore the view state of a server control across multiple requests for the same page. (Inherited from Control.)
Protected propertyViewStateIgnoresCaseGets a value that indicates whether the StateBag object is case-insensitive. (Inherited from Control.)
Public propertyViewStateModeGets or sets the view-state mode of this control. (Inherited from Control.)
Public propertyVisibleGets or sets a value that indicates whether a server control is rendered as UI on the page. (Inherited from Control.)
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  NameDescription
Protected methodAddedControlCalled after a child control is added to the Controls collection of the Control object. (Inherited from Control.)
Protected methodAddParsedSubObjectNotifies the server control that an element, either XML or HTML, was parsed, and adds the element to the server control's ControlCollection object. (Inherited from Control.)
Public methodApplyStyleSheetSkinApplies the style properties defined in the page style sheet to the control. (Inherited from Control.)
Protected methodBeginRenderTracingBegins design-time tracing of rendering data. (Inherited from Control.)
Protected methodBuildProfileTreeInfrastructure. Gathers information about the server control and delivers it to the Trace property to be displayed when tracing is enabled for the page. (Inherited from Control.)
Protected methodClearCachedClientIDInfrastructure. Sets the cached ClientID value to null. (Inherited from Control.)
Protected methodClearChildControlStateDeletes the control-state information for the server control's child controls. (Inherited from Control.)
Protected methodClearChildStateDeletes the view-state and control-state information for all the server control's child controls. (Inherited from Control.)
Protected methodClearChildViewStateDeletes the view-state information for all the server control's child controls. (Inherited from Control.)
Protected methodClearEffectiveClientIDModeInfrastructure. Sets the ClientIDMode property of the current control instance and of any child controls to Inherit. (Inherited from Control.)
Protected methodCreateChildControlsCalled by the ASP.NET page framework to notify server controls that use composition-based implementation to create any child controls they contain in preparation for posting back or rendering. (Inherited from Control.)
Protected methodCreateControlCollectionCreates a new ControlCollection object to hold the child controls (both literal and server) of the server control. (Inherited from Control.)
Public methodDataBind()Binds a data source to the invoked server control and all its child controls. (Inherited from Control.)
Protected methodDataBind(Boolean)Binds a data source to the invoked server control and all its child controls with an option to raise the DataBinding event. (Inherited from Control.)
Protected methodDataBindChildrenBinds a data source to the server control's child controls. (Inherited from Control.)
Public methodDisposeEnables a server control to perform final clean up before it is released from memory. (Inherited from Control.)
Protected methodEndRenderTracingEnds design-time tracing of rendering data. (Inherited from Control.)
Protected methodEnsureChildControlsDetermines whether the server control contains child controls. If it does not, it creates child controls. (Inherited from Control.)
Protected methodEnsureIDCreates an identifier for controls that do not have an identifier assigned. (Inherited from Control.)
Public methodEquals(Object)Determines whether the specified object is equal to the current object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodFindControl(String)Searches the current naming container for a server control with the specified id parameter. (Inherited from Control.)
Protected methodFindControl(String, Int32)Infrastructure. Searches the current naming container for a server control with the specified id and an integer, specified in the pathOffset parameter, which aids in the search. You should not override this version of the FindControl method. (Inherited from Control.)
Public methodFocusSets input focus to a control. (Inherited from Control.)
Protected methodGetDesignModeStateInfrastructure. Gets design-time data for a control. (Inherited from Control.)
Public methodGetHashCodeServes as the default hash function. (Inherited from Object.)
Public methodGetRouteUrl(Object)Gets the URL that corresponds to a set of route parameters. (Inherited from Control.)
Public methodGetRouteUrl(RouteValueDictionary)Gets the URL that corresponds to a set of route parameters. (Inherited from Control.)
Public methodGetRouteUrl(String, Object)Gets the URL that corresponds to a set of route parameters and a route name. (Inherited from Control.)
Public methodGetRouteUrl(String, RouteValueDictionary)Gets the URL that corresponds to a set of route parameters and a route name. (Inherited from Control.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodGetUniqueIDRelativeToReturns the prefixed portion of the UniqueID property of the specified control. (Inherited from Control.)
Public methodHasControlsDetermines if the server control contains any child controls. (Inherited from Control.)
Protected methodHasEventsReturns a value indicating whether events are registered for the control or any child controls. (Inherited from Control.)
Protected methodIsLiteralContentInfrastructure. Determines if the server control holds only literal content. (Inherited from Control.)
Protected methodLoadControlStateRestores control-state information from a previous page request that was saved by the SaveControlState method. (Inherited from Control.)
Protected methodLoadViewStateLoads the state of the values in the QueryExtender control that must be persisted. (Overrides Control.LoadViewState(Object).)
Protected methodMapPathSecureRetrieves the physical path that a virtual path, either absolute or relative, maps to. (Inherited from Control.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Protected methodOnBubbleEventDetermines whether the event for the server control is passed up the page's UI server control hierarchy. (Inherited from Control.)
Protected methodOnDataBindingRaises the DataBinding event. (Inherited from Control.)
Protected methodOnInitOccurs when a new instance of the QueryExtender class is initialized. (Overrides Control.OnInit(EventArgs).)
Protected methodOnLoadRaises the Load event. (Inherited from Control.)
Protected methodOnPreRenderRaises the PreRender event. (Inherited from Control.)
Protected methodOnUnloadRaises the Unload event. (Inherited from Control.)
Protected methodOpenFileGets a Stream used to read a file. (Inherited from Control.)
Protected methodRaiseBubbleEventAssigns any sources of the event and its information to the control's parent. (Inherited from Control.)
Protected methodRemovedControlCalled after a child control is removed from the Controls collection of the Control object. (Inherited from Control.)
Protected methodRenderSends server control content to a provided HtmlTextWriter object, which writes the content to be rendered on the client. (Inherited from Control.)
Protected methodRenderChildrenOutputs the content of a server control's children to a provided HtmlTextWriter object, which writes the content to be rendered on the client. (Inherited from Control.)
Public methodRenderControl(HtmlTextWriter)Outputs server control content to a provided HtmlTextWriter object and stores tracing information about the control if tracing is enabled. (Inherited from Control.)
Protected methodRenderControl(HtmlTextWriter, ControlAdapter)Outputs server control content to a provided HtmlTextWriter object using a provided ControlAdapter object. (Inherited from Control.)
Protected methodResolveAdapterGets the control adapter responsible for rendering the specified control. (Inherited from Control.)
Public methodResolveClientUrlGets a URL that can be used by the browser. (Inherited from Control.)
Public methodResolveUrlConverts a URL into one that is usable on the requesting client. (Inherited from Control.)
Protected methodSaveControlStateSaves any server control state changes that have occurred since the time the page was posted back to the server. (Inherited from Control.)
Protected methodSaveViewStateSaves the current view state of the QueryExtender control. (Overrides Control.SaveViewState().)
Protected methodSetDesignModeStateSets design-time data for a control. (Inherited from Control.)
Public methodSetRenderMethodDelegateInfrastructure. Assigns an event handler delegate to render the server control and its content into its parent control. (Inherited from Control.)
Public methodSetTraceData(Object, Object)Sets trace data for design-time tracing of rendering data, using the trace data key and the trace data value. (Inherited from Control.)
Public methodSetTraceData(Object, Object, Object)Sets trace data for design-time tracing of rendering data, using the traced object, the trace data key, and the trace data value. (Inherited from Control.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
Protected methodTrackViewStateTracks view-state changes of the QueryExtender control so that the changes can be stored in the StateBag object for the control. (Overrides Control.TrackViewState().)
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  NameDescription
Public eventDataBindingOccurs when the server control binds to a data source. (Inherited from Control.)
Public eventDisposedOccurs when a server control is released from memory, which is the last stage of the server control lifecycle when an ASP.NET page is requested. (Inherited from Control.)
Public eventInitOccurs when the server control is initialized, which is the first step in its lifecycle. (Inherited from Control.)
Public eventLoadOccurs when the server control is loaded into the Page object. (Inherited from Control.)
Public eventPreRenderOccurs after the Control object is loaded but prior to rendering. (Inherited from Control.)
Public eventUnloadOccurs when the server control is unloaded from memory. (Inherited from Control.)
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  NameDescription
Public Extension MethodFindDataSourceControlReturns the data source that is associated with the data control for the specified control. (Defined by DynamicDataExtensions.)
Public Extension MethodFindFieldTemplateReturns the field template for the specified column in the specified control's naming container. (Defined by DynamicDataExtensions.)
Public Extension MethodFindMetaTableReturns the metatable object for the containing data control. (Defined by DynamicDataExtensions.)
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  NameDescription
Explicit interface implemetationPrivate propertyIControlBuilderAccessor.ControlBuilderFor a description of this member, see IControlBuilderAccessor.ControlBuilder. (Inherited from Control.)
Explicit interface implemetationPrivate methodIControlDesignerAccessor.GetDesignModeStateFor a description of this member, see IControlDesignerAccessor.GetDesignModeState. (Inherited from Control.)
Explicit interface implemetationPrivate methodIControlDesignerAccessor.SetDesignModeStateFor a description of this member, see IControlDesignerAccessor.SetDesignModeState. (Inherited from Control.)
Explicit interface implemetationPrivate methodIControlDesignerAccessor.SetOwnerControlInfrastructure. For a description of this member, see IControlDesignerAccessor.SetOwnerControl. (Inherited from Control.)
Explicit interface implemetationPrivate propertyIControlDesignerAccessor.UserDataFor a description of this member, see IControlDesignerAccessor.UserData. (Inherited from Control.)
Explicit interface implemetationPrivate propertyIDataBindingsAccessor.DataBindingsFor a description of this member, see IDataBindingsAccessor.DataBindings. (Inherited from Control.)
Explicit interface implemetationPrivate propertyIDataBindingsAccessor.HasDataBindingsFor a description of this member, see IDataBindingsAccessor.HasDataBindings. (Inherited from Control.)
Explicit interface implemetationPrivate propertyIExpressionsAccessor.ExpressionsFor a description of this member, see IExpressionsAccessor.Expressions. (Inherited from Control.)
Explicit interface implemetationPrivate propertyIExpressionsAccessor.HasExpressionsFor a description of this member, see IExpressionsAccessor.HasExpressions. (Inherited from Control.)
Explicit interface implemetationPrivate methodIParserAccessor.AddParsedSubObjectFor a description of this member, see IParserAccessor.AddParsedSubObject. (Inherited from Control.)
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In this topic:

Introduction

The QueryExtender control is used to create filters for data that is retrieved from a data source, without using an explicit Where clause in the data source. The QueryExtender control can be used to specify filtering by using declarative syntax.

Background

Filtering excludes data from a data source by displaying only the records that meet specified criteria. Filtering enables you to present different views of the data that is in a data set without affecting the data in the data set.

Filtering typically requires that you create a Where clause to apply to the command that queries the data source. However, the Where property of the data source control might not expose the full functionality that is available. For example, the QueryExtender control enables you to query a table by searching for strings at the beginning, end or anywhere in .data field.

To expose the full functionality that is available in LINQ and to make filtering data easier, ASP.NET provides the QueryExtender control. The QueryExtender control has the following benefits:

  • It provides a richer filtering experience than writing a Where clause. For example, you can search a Products table for Boolean values by using the PropertyExpression filter without writing a query.

  • It lets you specify filters by using the same syntax for the LinqDataSource and EntityDataSource controls and for any other data source controls that you might use.

  • It can be used with LinqDataSource control, with a EntityDataSource control, or with third-party data sources.

Filter Options

The QueryExtender control supports a variety of options that you can use to filter data. The control lets you search strings, search numeric values in a specified range, and compare a property value in a table to a specified value. The control also lets you sort the data and provide custom queries.

These options are provided as LINQ expressions in the QueryExtender control. The QueryExtender control also supports expressions that are specific to ASP.NET Dynamic Data applications.

The following table lists the options that you can use to filter data in the QueryExtender control.

Expression

Description

ControlFilterExpression

(Dynamic Data only) Builds a database query by using the data key that is selected in a source data-bound control.

For information about how to use this filter option, see How to: Select Table Rows Using a Data Key in Dynamic Data.

CustomExpression

Specifies a user-defined expression for a data source. The custom LINQ expression can be invoked in an event handler.

DynamicFilterExpression

(Dynamic Data only) Builds a database query by using the specified DynamicFilter control.

For information about how to use this filter option, see How to: Select Table Rows Using Custom Filtering in Dynamic Data.

MethodExpression

Specifies a user-defined LINQ expression for a data source. The expression is invoked in a method.

OrderByExpression

Applies a sort expression to an IQueryable data source object. After you apply the OrderByExpression value, you can apply additional sort operations by specifying a ThenByExpressions value.

PropertyExpression

Compares the properties the data field and property values that are specified in the WhereParameters collection.

RangeExpression

Determines whether a value is greater than or less than a specified value, or whether a value is between two values.

SearchExpression

Compares values in a field or fields to a specified string value.

You can use these QueryExtender options individually or you can combine them to provide complex filtering in a Web page. For more information, see QueryExtender Web Server Control Overview. Walkthrough: Filtering Data in a Web Page Using Declarative Syntax

Tasks

The following table lists tasks that show how to use the QueryExtender control to filter data.

Document

Task

Walkthrough: Filtering Data in a Web Page Using Declarative Syntax

Shows how to use the filter options that the QueryExtender control provides.

Declarative Syntax

<asp:QueryExtender 
    EnableViewState="True|False"
    ID="string"
    OnDataBinding="DataBiding event handler"
    OnDisposed="Disposed event handler"
    OnInit="Init event handler
    OnLoad="Load event handler"
    OnPreRender="PreRender event handler"
    OnUnload="UnLoad event hadler"
    Runat="server"
    TargetControlID="string"
    Visible="True|False"
>
        <asp:ControlFilterExpression 
            ControlD="string"
            Column="string"> 
        </asp:ControlFilterExpression>
        <asp:DynamicFilterExpression
            ControlD="string"
        </asp:DynamicFilterExpression>
        <asp:CustomExpression="string"
            OnQuerying="OnQerying event handler">
        </asp:CustomExpression>
        <asp:OrderByExpression="string"
            DataField="string"
            Direction="string">
            <asp:ThenByExpression
                 DataField="string"
                 Direction="string"
            </asp:ThenBy>
        </asp:OrderByExpression>
        <asp:PropertyExpression="string">
                <!-- child controls -->
        </asp:PropertyExpression
        >
        <asp:RangeExpression="integer"
            Datafield="string"
            MaxType="Exclusive|Inclusive|None"
            MinType="Exclusive|Inclusive|None">
                <!--child controls-->
        </asp:RangeExpression>
        <asp:SearchExpression="string"
            ComparisonType="CurrentCulture|CurrentCultureIgnoreCase|
                InavariantCulture|InvariantCultureIgnoreCase|
                Ordinal|OrdinalIgnoreCase"
            DataField="string"
            SearchType="Contains|EndsWith|StartsWith">
                <!--child controls-->
        </asp:SearchExpression>
</asp:QueryExtender>

The following example shows how to use the QueryExtender control to provide a search function in a Web page. The QueryExtender control uses the text that is entered in the TextBoxSearch control to search for contents in the ProductName and Supplier.CompanyName columns of a Products table in the data that is returned from the LinqDataSource control. The SearchExpression object is used to perform the search. The DataFields property specifies the data fields to search. The SearchType property specifies the type of search to perform. The ControlParameter element specifies the control that contains the text to use for the search. This code example is part of a larger example that is provided in Walkthrough: Filtering Data in a Web Page Using Declarative Syntax.

<asp:LinqDataSource ID="dataSource" runat="server" 
    TableName="Products">
</asp:LinqDataSource>
<asp:QueryExtender TargetControlID="dataSource" runat="server">
  <asp:SearchExpression DataFields="ProductName, Supplier.CompanyName" 
        SearchType="StartsWith">
    <asp:ControlParameter ControlID="TextBoxSearch" />
  </asp:SearchExpression>
</asp:QueryExtender>

The following example shows how to use the QueryExtender control to search a Web page for values in a specified range. The QueryExtender control uses the values that are entered in the TextBoxFrom and TextBoxTo controls to search for values in the ProductName and Supplier.CompanyName columns of a Products table in the data that is returned from the LinqDataSource control. The ControlParameter element specifies the text box controls that contain the minimum and maximum values to use for searching the range. The MinType and MaxType properties specify that the minimum and maximum values must be included in the data that is returned. This code example is part of a larger example provided in Walkthrough: Filtering Data in a Web Page Using Declarative Syntax.

<asp:LinqDataSource ID="dataSource" runat="server" 
    TableName="Products">
</asp:LinqDataSource>
<asp:QueryExtender TargetControlID="dataSource" runat="server">
  <asp:RangeExpression DataField="UnitPrice" MinType="Inclusive" 
        MaxType="Inclusive">
    <asp:ControlParameter ControlID="TextBoxFrom" />
    <asp:ControlParameter ControlID="TexBoxTo" />
  </asp:RangeExpression>
</asp:QueryExtender>

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
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