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DropDownList Class

Represents a control that allows the user to select a single item from a drop-down list.

Namespace:  System.Web.UI.WebControls
Assembly:  System.Web (in System.Web.dll)
[ValidationPropertyAttribute("SelectedItem")]
public class DropDownList : ListControl, 
	IPostBackDataHandler
<asp:DropDownList />

The DropDownList type exposes the following members.

  NameDescription
Public methodDropDownListInitializes a new instance of the DropDownList class.
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  NameDescription
Public propertyAccessKeyGets or sets the access key that allows you to quickly navigate to the Web server control. (Inherited from WebControl.)
Protected propertyAdapterGets the browser-specific adapter for the control. (Inherited from Control.)
Public propertyAppendDataBoundItemsGets or sets a value that indicates whether list items are cleared before data binding. (Inherited from ListControl.)
Public propertyAppRelativeTemplateSourceDirectoryGets or sets the application-relative virtual directory of the Page or UserControl object that contains this control. (Inherited from Control.)
Public propertyAttributesGets the collection of arbitrary attributes (for rendering only) that do not correspond to properties on the control. (Inherited from WebControl.)
Public propertyAutoPostBackGets or sets a value indicating whether a postback to the server automatically occurs when the user changes the list selection. (Inherited from ListControl.)
Public propertyBackColorGets or sets the background color of the Web server control. (Inherited from WebControl.)
Public propertyBindingContainerInfrastructure. Gets the control that contains this control's data binding. (Inherited from Control.)
Public propertyBorderColorGets or sets the border color of the control. (Overrides WebControl.BorderColor.)
Public propertyBorderStyleGets or sets the border style of the control. (Overrides WebControl.BorderStyle.)
Public propertyBorderWidthGets or sets the border width for the control. (Overrides WebControl.BorderWidth.)
Public propertyCausesValidationGets or sets a value indicating whether validation is performed when a control that is derived from the ListControl class is clicked. (Inherited from ListControl.)
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 propertyControlStyleGets the style of the Web server control. This property is used primarily by control developers. (Inherited from WebControl.)
Public propertyControlStyleCreatedGets a value indicating whether a Style object has been created for the ControlStyle property. This property is primarily used by control developers. (Inherited from WebControl.)
Public propertyCssClassGets or sets the Cascading Style Sheet (CSS) class rendered by the Web server control on the client. (Inherited from WebControl.)
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 propertyDataMemberGets or sets the name of the list of data that the data-bound control binds to, in cases where the data source contains more than one distinct list of data items. (Inherited from DataBoundControl.)
Public propertyDataSourceGets or sets the object from which the data-bound control retrieves its list of data items. (Inherited from BaseDataBoundControl.)
Public propertyDataSourceIDGets or sets the ID of the control from which the data-bound control retrieves its list of data items. (Inherited from DataBoundControl.)
Public propertyDataSourceObjectGets an object that implements the IDataSource interface, which provides access to the object's data content. (Inherited from DataBoundControl.)
Public propertyDataTextFieldGets or sets the field of the data source that provides the text content of the list items. (Inherited from ListControl.)
Public propertyDataTextFormatStringGets or sets the formatting string used to control how data bound to the list control is displayed. (Inherited from ListControl.)
Public propertyDataValueFieldGets or sets the field of the data source that provides the value of each list item. (Inherited from ListControl.)
Protected propertyDesignModeGets a value indicating whether a control is being used on a design surface. (Inherited from Control.)
Public propertyEnabledGets or sets a value indicating whether the Web server control is enabled. (Inherited from WebControl.)
Public propertyEnableThemingGets or sets a value indicating whether themes apply to this control. (Inherited from WebControl.)
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 propertyFontGets the font properties associated with the Web server control. (Inherited from WebControl.)
Public propertyForeColorGets or sets the foreground color (typically the color of the text) of the Web server control. (Inherited from WebControl.)
Public propertyHasAttributesGets a value indicating whether the control has attributes set. (Inherited from WebControl.)
Protected propertyHasChildViewStateGets a value indicating whether the current server control's child controls have any saved view-state settings. (Inherited from Control.)
Public propertyHeightGets or sets the height of the Web server control. (Inherited from WebControl.)
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 propertyInitializedGets a value indicating whether the data-bound control has been initialized. (Inherited from BaseDataBoundControl.)
Protected propertyIsBoundUsingDataSourceIDGets a value indicating whether the DataSourceID property is set. (Inherited from BaseDataBoundControl.)
Protected propertyIsChildControlStateClearedGets a value indicating whether controls contained within this control have control state. (Inherited from Control.)
Protected propertyIsDataBindingAutomaticGets a value that indicates whether data binding is automatic. (Inherited from BaseDataBoundControl.)
Protected propertyIsEnabledGets a value indicating whether the control is enabled. (Inherited from WebControl.)
Protected propertyIsTrackingViewStateGets a value that indicates whether the server control is saving changes to its view state. (Inherited from Control.)
Protected propertyIsUsingModelBindersGets a value that indicates whether model binding is in use. (Inherited from DataBoundControl.)
Protected propertyIsViewStateEnabledGets a value indicating whether view state is enabled for this control. (Inherited from Control.)
Public propertyItemsGets the collection of items in the list control. (Inherited from ListControl.)
Public propertyItemTypeGets or sets the name of the data item type for strongly typed data binding. (Inherited from DataBoundControl.)
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.)
Protected propertyRequiresDataBindingGets or sets a value indicating whether the DataBind method should be called. (Inherited from BaseDataBoundControl.)
Protected propertySelectArgumentsGets a DataSourceSelectArguments object that the data-bound control uses when retrieving data from a data source control. (Inherited from DataBoundControl.)
Public propertySelectedIndexGets or sets the index of the selected item in the DropDownList control. (Overrides ListControl.SelectedIndex.)
Public propertySelectedItemGets the selected item with the lowest index in the list control. (Inherited from ListControl.)
Public propertySelectedValueGets the value of the selected item in the list control, or selects the item in the list control that contains the specified value. (Inherited from ListControl.)
Public propertySelectMethodThe name of the method to call in order to read data. (Inherited from DataBoundControl.)
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 WebControl.)
Public propertyStyleGets a collection of text attributes that will be rendered as a style attribute on the outer tag of the Web server control. (Inherited from WebControl.)
Public propertySupportsDisabledAttributeGets a value that indicates whether the control should set the disabled attribute of the rendered HTML element to "disabled" when the control's IsEnabled property is false. (Overrides BaseDataBoundControl.SupportsDisabledAttribute.)
Public propertyTabIndexGets or sets the tab index of the Web server control. (Inherited from WebControl.)
Protected propertyTagKeyGets the HtmlTextWriterTag value for the ListControl control. (Inherited from ListControl.)
Protected propertyTagNameGets the name of the control tag. This property is used primarily by control developers. (Inherited from WebControl.)
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 propertyTextGets or sets the SelectedValue property of the ListControl control. (Inherited from ListControl.)
Public propertyToolTipGets or sets the text displayed when the mouse pointer hovers over the Web server control. (Inherited from WebControl.)
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.)
Public propertyValidationGroupGets or sets the group of controls for which the control that is derived from the ListControl class causes validation when it posts back to the server. (Inherited from ListControl.)
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.)
Public propertyWidthGets or sets the width of the Web server control. (Inherited from WebControl.)
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  NameDescription
Protected methodAddAttributesToRenderAdds HTML attributes and styles that need to be rendered to the specified HtmlTextWriter object. (Overrides ListControl.AddAttributesToRender(HtmlTextWriter).)
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 methodApplyStyleCopies any nonblank elements of the specified style to the Web control, overwriting any existing style elements of the control. This method is primarily used by control developers. (Inherited from WebControl.)
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.)
Public methodClearSelectionClears out the list selection and sets the Selected property of all items to false. (Inherited from ListControl.)
Protected methodConfirmInitStateSets the initialized state of the data-bound control. (Inherited from BaseDataBoundControl.)
Public methodCopyBaseAttributesCopies the properties not encapsulated by the Style object from the specified Web server control to the Web server control that this method is called from. This method is used primarily by control developers. (Inherited from WebControl.)
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 collection to store child controls. (Overrides Control.CreateControlCollection().)
Protected methodCreateControlStyleCreates the style object that is used internally by the WebControl class to implement all style related properties. This method is used primarily by control developers. (Inherited from WebControl.)
Protected methodCreateDataSourceSelectArgumentsCreates a default DataSourceSelectArguments object used by the data-bound control if no arguments are specified. (Inherited from DataBoundControl.)
Public methodDataBind()Binds a data source to the invoked server control and all its child controls. (Inherited from BaseDataBoundControl.)
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 methodEnsureDataBoundCalls the DataBind method if the DataSourceID property is set and the data-bound control is marked to require binding. (Inherited from BaseDataBoundControl.)
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 methodGetDataRetrieves a DataSourceView object that the data-bound control uses to perform data operations. (Inherited from DataBoundControl.)
Protected methodGetDataSourceRetrieves the IDataSource interface that the data-bound control is associated with, if any. (Inherited from DataBoundControl.)
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 methodLoadPostDataProcesses postback data for the DropDownList control.
Protected methodLoadViewStateLoads the previously saved view state of the DetailsView control. (Inherited from ListControl.)
Protected methodMapPathSecureRetrieves the physical path that a virtual path, either absolute or relative, maps to. (Inherited from Control.)
Protected methodMarkAsDataBoundSets the state of the control in view state as successfully bound to data. (Inherited from DataBoundControl.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodMergeStyleCopies any nonblank elements of the specified style to the Web control, but will not overwrite any existing style elements of the control. This method is used primarily by control developers. (Inherited from WebControl.)
Protected methodOnBubbleEventDetermines whether the event for the server control is passed up the page's UI server control hierarchy. (Inherited from Control.)
Protected methodOnCreatingModelDataSourceRaises the CreatingModelDataSource event. (Inherited from DataBoundControl.)
Protected methodOnDataBindingInfrastructure. Raises the DataBinding event. (Inherited from ListControl.)
Protected methodOnDataBoundRaises the DataBound event. (Inherited from BaseDataBoundControl.)
Protected methodOnDataPropertyChangedRebinds the data-bound control to its data after one of the base data source identification properties changes. (Inherited from DataBoundControl.)
Protected methodOnDataSourceViewChangedRaises the DataSourceViewChanged event. (Inherited from DataBoundControl.)
Protected methodOnInitHandles the Init event. (Inherited from BaseDataBoundControl.)
Protected methodOnLoadHandles the Control.Load event. (Inherited from DataBoundControl.)
Protected methodOnPagePreLoadSets the initialized state of the data-bound control before the control is loaded. (Inherited from DataBoundControl.)
Protected methodOnPreRenderRaises the PreRender event. (Inherited from ListControl.)
Protected methodOnSelectedIndexChangedRaises the SelectedIndexChanged event. This allows you to provide a custom handler for the event. (Inherited from ListControl.)
Protected methodOnTextChangedRaises the TextChanged event. (Inherited from ListControl.)
Protected methodOnUnloadRaises the Unload event. (Inherited from Control.)
Protected methodOpenFileGets a Stream used to read a file. (Inherited from Control.)
Protected methodPerformDataBindingInfrastructure. Binds the specified data source to the control that is derived from the ListControl class. (Inherited from ListControl.)
Protected methodPerformSelectRetrieves data from the associated data source. (Inherited from ListControl.)
Protected methodRaiseBubbleEventAssigns any sources of the event and its information to the control's parent. (Inherited from Control.)
Protected methodRaisePostDataChangedEventRaises events for the DropDownList control when postback occurs.
Protected methodRemovedControlCalled after a child control is removed from the Controls collection of the Control object. (Inherited from Control.)
Protected methodRenderRenders the control to the specified HTML writer. (Inherited from WebControl.)
Public methodRenderBeginTagRenders the HTML opening tag of the control to the specified writer. This method is used primarily by control developers. (Inherited from WebControl.)
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.)
Protected methodRenderContentsRenders the items in the ListControl control. (Inherited from ListControl.)
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.)
Public methodRenderEndTagRenders the HTML closing tag of the control into the specified writer. This method is used primarily by control developers. (Inherited from WebControl.)
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 ListControl -derived control and the items it contains. (Inherited from ListControl.)
Protected methodSetDesignModeStateSets design-time data for a control. (Inherited from Control.)
Protected methodSetPostDataSelectionInfrastructure. Sets the Selected property of a ListItem control after a page is posted. (Inherited from ListControl.)
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 methodTrackViewStateMarks the starting point to begin tracking and saving view-state changes to a ListControl -derived control. (Inherited from ListControl.)
Protected methodValidateDataSourceVerifies that the object a data-bound control binds to is one it can work with. (Inherited from DataBoundControl.)
Protected methodVerifyMultiSelectAlways throws an HttpException exception because multiple selection is not supported for the DropDownList control. (Overrides ListControl.VerifyMultiSelect().)
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  NameDescription
Public eventCallingDataMethodsOccurs when data methods are being called. (Inherited from DataBoundControl.)
Public eventCreatingModelDataSourceOccurs when the ModelDataSource object is being created. (Inherited from DataBoundControl.)
Public eventDataBindingOccurs when the server control binds to a data source. (Inherited from Control.)
Public eventDataBoundOccurs after the server control binds to a data source. (Inherited from BaseDataBoundControl.)
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 eventSelectedIndexChangedOccurs when the selection from the list control changes between posts to the server. (Inherited from ListControl.)
Public eventTextChangedOccurs when the Text and SelectedValue properties change. (Inherited from ListControl.)
Public eventUnloadOccurs when the server control is unloaded from memory. (Inherited from Control.)
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  NameDescription
Public Extension MethodEnablePersistedSelectionEnables selection to be persisted in data controls that support selection and paging. (Defined by DynamicDataExtensions.)
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 methodIAttributeAccessor.GetAttributeInfrastructure. Gets an attribute of the Web control with the specified name. (Inherited from WebControl.)
Explicit interface implemetationPrivate methodIAttributeAccessor.SetAttributeSets an attribute of the Web control to the specified name and value. (Inherited from WebControl.)
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.)
Explicit interface implemetationPrivate methodIPostBackDataHandler.LoadPostDataInfrastructure. Processes posted data for the DropDownList control.
Explicit interface implemetationPrivate methodIPostBackDataHandler.RaisePostDataChangedEventInfrastructure. Raises events for the DropDownList control on postback.
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In this topic:

Introduction

Use the DropDownList control to create a single-selection drop-down list control. You can control the appearance of the DropDownList control by setting the BorderColor, BorderStyle, and BorderWidth properties.

To specify the items that you want to appear in the DropDownList control, place a ListItem object for each entry between the opening and closing tags of the DropDownList control.

The DropDownList control also supports data binding. To bind the control to a data source, create a data source, such as a System.Collections.ArrayList object, that contains the items to display in the control. Then, use the Control.DataBind method to bind the data source to the DropDownList control.

Use the SelectedIndex property to programmatically determine the index of the item selected by the user from the DropDownList control. The index can then be used to retrieve the selected item from the Items collection of the control.

Accessibility

For information about how to configure this control so that it generates markup that conforms to accessibility standards, see Accessibility in Visual Studio and ASP.NET and ASP.NET Controls and Accessibility.

Declarative Syntax

<asp:DropDownList
    AccessKey="string"
    AppendDataBoundItems="True|False"
    AutoPostBack="True|False"
    BackColor="color name|#dddddd"
    BorderColor="color name|#dddddd"
    BorderStyle="NotSet|None|Dotted|Dashed|Solid|Double|Groove|Ridge|
        Inset|Outset"
    BorderWidth="size"
    CausesValidation="True|False"
    CssClass="string"
    DataMember="string"
    DataSource="string"
    DataSourceID="string"
    DataTextField="string"
    DataTextFormatString="string"
    DataValueField="string"
    Enabled="True|False"
    EnableTheming="True|False"
    EnableViewState="True|False"
    Font-Bold="True|False"
    Font-Italic="True|False"
    Font-Names="string"
    Font-Overline="True|False"
    Font-Size="string|Smaller|Larger|XX-Small|X-Small|Small|Medium|
        Large|X-Large|XX-Large"
    Font-Strikeout="True|False"
    Font-Underline="True|False"
    ForeColor="color name|#dddddd"
    Height="size"
    ID="string"
    OnDataBinding="DataBinding event handler"
    OnDataBound="DataBound event handler"
    OnDisposed="Disposed event handler"
    OnInit="Init event handler"
    OnLoad="Load event handler"
    OnPreRender="PreRender event handler"
    OnSelectedIndexChanged="SelectedIndexChanged event handler"
    OnTextChanged="TextChanged event handler"
    OnUnload="Unload event handler"
    runat="server"
    SelectedIndex="integer"
    SelectedValue="string"
    SkinID="string"
    Style="string"
    TabIndex="integer"
    ToolTip="string"
    ValidationGroup="string"
    Visible="True|False"
    Width="size"
>
            <asp:ListItem
                Enabled="True|False"
                Selected="True|False"
                Text="string"
                Value="string"
            />
</asp:DropDownList>
TopicLocation
How to: Add DropDownList Web Server Controls to a Web Forms PageBuilding ASP .NET Web Applications
How to: Respond to Changes in List Web Server ControlsBuilding ASP .NET Web Applications
How to: Set Focus on ASP.NET Web Server ControlsBuilding ASP .NET Web Applications
How to: Determine the Selection in List Web Server ControlsBuilding ASP .NET Web Applications
How to: Populate List Web Server Controls from a Data SourceBuilding ASP .NET Web Applications
How to: Display Site-Map Data in Non-Hierarchical Web Server ControlsBuilding ASP .NET Web Applications
How to: Add Items in List Web Server ControlsBuilding ASP .NET Web Applications
How to: Set the Selection in List Web Server ControlsBuilding ASP .NET Web Applications
How to: Add DropDownList Web Server Controls to a Web Forms PageBuilding ASP .NET Web Applications
How to: Respond to Changes in List Web Server ControlsBuilding ASP .NET Web Applications
How to: Set Focus on ASP.NET Web Server ControlsBuilding ASP .NET Web Applications
How to: Determine the Selection in List Web Server ControlsBuilding ASP .NET Web Applications
How to: Populate List Web Server Controls from a Data SourceBuilding ASP .NET Web Applications
How to: Display Site-Map Data in Non-Hierarchical Web Server ControlsBuilding ASP .NET Web Applications
How to: Add Items in List Web Server ControlsBuilding ASP .NET Web Applications
How to: Set the Selection in List Web Server ControlsBuilding ASP .NET Web Applications
How to: Set the Selection in List Web Server Controls (Visual Studio)Building ASP .NET Web Applications in Visual Studio
How to: Add DropDownList Web Server Controls to a Web Forms Page (Visual Studio)Building ASP .NET Web Applications in Visual Studio
Walkthrough: Creating and Using ASP.NET Master Pages in Visual Web DeveloperBuilding ASP .NET Web Applications in Visual Studio
Walkthrough: Displaying Formatted Data in Web Pages with the FormView Web Server ControlBuilding ASP .NET Web Applications in Visual Studio
How to: Populate List Web Server Controls from a Data Source (Visual Studio)Building ASP .NET Web Applications in Visual Studio
Walkthrough: Creating a Web Page to Display XML DataBuilding ASP .NET Web Applications in Visual Studio
Walkthrough: Data Binding to a Custom Business ObjectBuilding ASP .NET Web Applications in Visual Studio
Walkthrough: Displaying a Drop-Down List While Editing in the GridView Web Server ControlBuilding ASP .NET Web Applications in Visual Studio
How to: Add Items in List Web Server Controls (Visual Studio)Building ASP .NET Web Applications in Visual Studio
Walkthrough: Creating Master/Detail Web Pages in Visual StudioBuilding ASP .NET Web Applications in Visual Studio
Walkthrough: Displaying an XML Document in a Web Forms Page Using TransformationsBuilding ASP .NET Web Applications in Visual Studio
Walkthrough: Displaying a Drop-Down List While Editing in the GridView Web Server ControlBuilding ASP .NET Web Applications in Visual Studio

A Visual Studio Web site project with source code is available to accompany this topic: Download.

The following code example demonstrates how to create a DropDownList control that contains four items.

<%@ Page Language="C#" AutoEventWireup="True" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
   <script runat="server" >

      void Selection_Change(Object sender, EventArgs e)
      {

         // Set the background color for days in the Calendar control
         // based on the value selected by the user from the 
         // DropDownList control.
         Calendar1.DayStyle.BackColor = 
             System.Drawing.Color.FromName(ColorList.SelectedItem.Value);

      }

   </script>

<head runat="server">
    <title> DropDownList Example </title>
</head>
<body>

   <form id="form1" runat="server">

      <h3> DropDownList Example </h3>

      Select a background color for days in the calendar.

      <br /><br /> 

      <asp:Calendar id="Calendar1"
           ShowGridLines="True" 
           ShowTitle="True"
           runat="server"/>

      <br /><br />

      <table cellpadding="5">

         <tr>

            <td>

               Background color:

            </td>

         </tr>

         <tr>

            <td>

               <asp:DropDownList id="ColorList"
                    AutoPostBack="True"
                    OnSelectedIndexChanged="Selection_Change"
                    runat="server">

                  <asp:ListItem Selected="True" Value="White"> White </asp:ListItem>
                  <asp:ListItem Value="Silver"> Silver </asp:ListItem>
                  <asp:ListItem Value="DarkGray"> Dark Gray </asp:ListItem>
                  <asp:ListItem Value="Khaki"> Khaki </asp:ListItem>
                  <asp:ListItem Value="DarkKhaki"> Dark Khaki </asp:ListItem>

               </asp:DropDownList>

            </td>

         </tr>

      </table>

   </form>

</body>
</html>
 

The following code example demonstrates how to create a DropDownList control though data binding.

<%@ Page Language="C#" AutoEventWireup="True" %>
<%@ Import Namespace="System.Data" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
   <script runat="server" >

      void Selection_Change(Object sender, EventArgs e)
      {

         // Set the background color for days in the Calendar control
         // based on the value selected by the user from the 
         // DropDownList control.
         Calendar1.DayStyle.BackColor = 
             System.Drawing.Color.FromName(ColorList.SelectedItem.Value);

      }

      void Page_Load(Object sender, EventArgs e)
      {

         // Load data for the DropDownList control only once, when the 
         // page is first loaded.
         if(!IsPostBack)
         {

            // Specify the data source and field names for the Text 
            // and Value properties of the items (ListItem objects) 
            // in the DropDownList control.
            ColorList.DataSource = CreateDataSource();
            ColorList.DataTextField = "ColorTextField";
            ColorList.DataValueField = "ColorValueField";

            // Bind the data to the control.
            ColorList.DataBind();

            // Set the default selected item, if desired.
            ColorList.SelectedIndex = 0;

         }

      }

      ICollection CreateDataSource() 
      {

         // Create a table to store data for the DropDownList control.
         DataTable dt = new DataTable();

         // Define the columns of the table.
         dt.Columns.Add(new DataColumn("ColorTextField", typeof(String)));
         dt.Columns.Add(new DataColumn("ColorValueField", typeof(String)));

         // Populate the table with sample values.
         dt.Rows.Add(CreateRow("White", "White", dt));
         dt.Rows.Add(CreateRow("Silver", "Silver", dt));
         dt.Rows.Add(CreateRow("Dark Gray", "DarkGray", dt));
         dt.Rows.Add(CreateRow("Khaki", "Khaki", dt));
         dt.Rows.Add(CreateRow("Dark Khaki", "DarkKhaki", dt));

         // Create a DataView from the DataTable to act as the data source
         // for the DropDownList control.
         DataView dv = new DataView(dt);
         return dv;

      }

      DataRow CreateRow(String Text, String Value, DataTable dt)
      {

         // Create a DataRow using the DataTable defined in the 
         // CreateDataSource method.
         DataRow dr = dt.NewRow();

         // This DataRow contains the ColorTextField and ColorValueField 
         // fields, as defined in the CreateDataSource method. Set the 
         // fields with the appropriate value. Remember that column 0 
         // is defined as ColorTextField, and column 1 is defined as 
         // ColorValueField.
         dr[0] = Text;
         dr[1] = Value;

         return dr;

      }

   </script>

<head runat="server">
    <title> DropDownList Data Binding Example </title>
</head>
<body>

   <form id="form1" runat="server">

      <h3> DropDownList Data Binding Example </h3>

      Select a background color for days in the calendar.

      <br /><br /> 

      <asp:Calendar id="Calendar1"
           ShowGridLines="True" 
           ShowTitle="True"
           runat="server"/>

      <br /><br />

      <table cellpadding="5">

         <tr>

            <td>

               Background color:

            </td>

         </tr>

         <tr>

            <td>

               <asp:DropDownList id="ColorList"
                    AutoPostBack="True"
                    OnSelectedIndexChanged="Selection_Change"
                    runat="server"/>

            </td>

         </tr>

      </table>   

   </form>

</body>
</html>
 

.NET Framework

Supported in: 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

Windows Phone 8.1, Windows Phone 8, 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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