HtmlInputFile Class
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Allows programmatic access to the HTML <input type= file> element on the server.
public ref class HtmlInputFile : System::Web::UI::HtmlControls::HtmlInputControl, System::Web::UI::IPostBackDataHandler[System.Web.UI.ValidationProperty("Value")]
public class HtmlInputFile : System.Web.UI.HtmlControls.HtmlInputControl, System.Web.UI.IPostBackDataHandler[<System.Web.UI.ValidationProperty("Value")>]
type HtmlInputFile = class
inherit HtmlInputControl
interface IPostBackDataHandlerPublic Class HtmlInputFile
Inherits HtmlInputControl
Implements IPostBackDataHandler- Inheritance
- Attributes
- Implements
Examples
The following code example demonstrates how to use the HtmlInputFile control to create a simple file upload scenario. For this example to work properly, you need to create a directory called Temp on your computer's drive C.
<%@ 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">
<script runat="server">
void Button1_Click(object Source, EventArgs e)
{
if (Text1.Value == "")
{
Span1.InnerHtml = "Error: You must enter a file name.";
return;
}
if (File1.PostedFile.ContentLength > 0)
{
try
{
File1.PostedFile.SaveAs("c:\\temp\\" + Text1.Value);
Span1.InnerHtml = "File uploaded successfully to <b>c:\\temp\\" +
Text1.Value + "</b> on the Web server.";
}
catch (Exception exc)
{
Span1.InnerHtml = "Error saving file <b>c:\\temp\\" +
Text1.Value + "</b><br />" + exc.ToString() + ".";
}
}
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title>HtmlInputFile Example</title>
</head>
<body>
<h3>HtmlInputFile Example</h3>
<form id="form1" enctype="multipart/form-data"
runat="server">
Select File to Upload:
<input id="File1"
type="file"
runat="server" />
<p>
Save as file name (no path):
<input id="Text1"
type="text"
runat="server" />
</p>
<p>
<span id="Span1"
style="font: 8pt verdana;"
runat="server" />
</p>
<p>
<input type="button"
id="Button1"
value="Upload"
onserverclick="Button1_Click"
runat="server" />
</p>
</form>
</body>
</html>
<%@ Page Language="VB" AutoEventWireup="True" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
Sub Button1_Click(ByVal Source As Object, ByVal e As EventArgs)
If Text1.Value = "" Then
Span1.InnerHtml = "Error: You must enter a file name."
Return
End If
If File1.PostedFile.ContentLength > 0 Then
Try
File1.PostedFile.SaveAs(("c:\temp\" & Text1.Value))
Span1.InnerHtml = "File uploaded successfully to <b>c:\temp\" & _
Text1.Value & "</b> on the Web server."
Catch exc As Exception
Span1.InnerHtml = "Error saving file <b>c:\temp\" & _
Text1.Value & "</b><br />" & exc.ToString() & "."
End Try
End If
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title>HtmlInputFile Example</title>
</head>
<body>
<h3>HtmlInputFile Example</h3>
<form id="form1" enctype="multipart/form-data"
runat="server">
Select File to Upload:
<input id="File1"
type="file"
runat="server" />
<p>
Save as file name (no path):
<input id="Text1"
type="text"
runat="server" />
</p>
<p>
<span id="Span1"
style="font: 8pt verdana;"
runat="server" />
</p>
<p>
<input type="button"
id="Button1"
value="Upload"
onserverclick="Button1_Click"
runat="server" />
</p>
</form>
</body>
</html>
Remarks
Use the HtmlInputFile server control to handle uploading binary or text files from a browser client to the server. File upload works with Microsoft Internet Explorer version 3.02 or later.
Note
The HtmlInputFile control is designed to be used only in postback scenarios and not in asynchronous postback scenarios during partial-page rendering. When you use a HtmlInputFile control inside an UpdatePanel control, the file must be uploaded by using a control that is a PostBackTrigger object for the panel. UpdatePanel controls are used to update selected regions of a page instead of updating the whole page with a postback. For more information, see UpdatePanel Control Overview and Partial-Page Rendering Overview.
To specify the file to upload, enter the full path to the file (for example, "C:\MyFiles\Test.txt") in the text box of the control. You can also select the file by clicking the Browse button and then locating it in the Choose file dialog box.
Note
The Enctype property of an HtmlForm control must be set to "multipart/form-data" for this control to work properly.
The HtmlInputFile control does not have a built-in way to post back to the server. To upload the file to the server, use the SaveAs method of the System.Web.HttpPostedFile object contained in the PostedFile property. This operation is usually done in an event-handling method, such as for a button click.
Note
When you use the SaveAs method of the HttpPostedFile class, make sure to specify a rooted path (for example, "C:\MyFiles\Test.txt"). The behavior of the SaveAs method can be specified in the httpRuntime Element (ASP.NET Settings Schema) configuration section with the requireRootedSaveAsPath attribute. The default value of this attribute is true. If you set this attribute to false, then using the SaveAs method with no path specified will attempt to place the file in the systemroot \system32\inetsrv directory. By default, this directory is write-protected; therefore, the file can not be saved there. Make sure to provide write permission for the account used by ASP.NET for the directory where you want to store the file.
When uploading large files, use the maxRequestLength attribute of the httpRuntime Element (ASP.NET Settings Schema) element to increase the maximum allowable file size. A DNS error is generated in the browser when the file exceeds the specified size. You might also receive the following error message when uploading large files:
aspnet_wp.exe (PID: 1520) was recycled because memory consumption exceeded 460 MB (60 percent of available RAM).
If you encounter this error message, increase the value of the memoryLimit attribute in the processModel Element (ASP.NET Settings Schema) element of the Machine.config file.
For a list of initial property values for an instance of HtmlInputFile, see the HtmlInputFile constructor.
Constructors
| HtmlInputFile() |
Initializes a new instance of the HtmlInputFile class. |
Properties
| Accept |
Gets or sets a comma-separated list of MIME encodings used to constrain the file types the user can select. |
| Adapter |
Gets the browser-specific adapter for the control. (Inherited from Control) |
| AppRelativeTemplateSourceDirectory |
Gets or sets the application-relative virtual directory of the Page or UserControl object that contains this control. (Inherited from Control) |
| Attributes |
Gets a collection of all attribute name and value pairs expressed on a server control tag within the ASP.NET page. (Inherited from HtmlControl) |
| BindingContainer |
Gets the control that contains this control's data binding. (Inherited from Control) |
| ChildControlsCreated |
Gets a value that indicates whether the server control's child controls have been created. (Inherited from Control) |
| ClientID |
Gets the control ID for HTML markup that is generated by ASP.NET. (Inherited from Control) |
| ClientIDMode |
Gets or sets the algorithm that is used to generate the value of the ClientID property. (Inherited from Control) |
| ClientIDSeparator |
Gets a character value representing the separator character used in the ClientID property. (Inherited from Control) |
| Context |
Gets the HttpContext object associated with the server control for the current Web request. (Inherited from Control) |
| Controls |
Gets a ControlCollection object that represents the child controls for a specified server control in the UI hierarchy. (Inherited from Control) |
| DataItemContainer |
Gets a reference to the naming container if the naming container implements IDataItemContainer. (Inherited from Control) |
| DataKeysContainer |
Gets a reference to the naming container if the naming container implements IDataKeysControl. (Inherited from Control) |
| DesignMode |
Gets a value indicating whether a control is being used on a design surface. (Inherited from Control) |
| Disabled |
Gets or sets a value indicating whether the HTML server control is disabled. (Inherited from HtmlControl) |
| EnableTheming |
Gets or sets a value indicating whether themes apply to this control. (Inherited from Control) |
| EnableViewState |
Gets 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) |
| Events |
Gets a list of event handler delegates for the control. This property is read-only. (Inherited from Control) |
| HasChildViewState |
Gets a value indicating whether the current server control's child controls have any saved view-state settings. (Inherited from Control) |
| ID |
Gets or sets the programmatic identifier assigned to the server control. (Inherited from Control) |
| IdSeparator |
Gets the character used to separate control identifiers. (Inherited from Control) |
| IsChildControlStateCleared |
Gets a value indicating whether controls contained within this control have control state. (Inherited from Control) |
| IsTrackingViewState |
Gets a value that indicates whether the server control is saving changes to its view state. (Inherited from Control) |
| IsViewStateEnabled |
Gets a value indicating whether view state is enabled for this control. (Inherited from Control) |
| LoadViewStateByID |
Gets a value indicating whether the control participates in loading its view state by ID instead of index. (Inherited from Control) |
| MaxLength |
Gets or sets the maximum length of the file path for the file to upload from the client computer. |
| Name |
Gets or sets the unique identifier name for the HtmlInputControl control. (Inherited from HtmlInputControl) |
| NamingContainer |
Gets a reference to the server control's naming container, which creates a unique namespace for differentiating between server controls with the same ID property value. (Inherited from Control) |
| Page |
Gets a reference to the Page instance that contains the server control. (Inherited from Control) |
| Parent |
Gets a reference to the server control's parent control in the page control hierarchy. (Inherited from Control) |
| PostedFile |
Gets access to the uploaded file specified by a client. |
| RenderingCompatibility |
Gets a value that specifies the ASP.NET version that rendered HTML will be compatible with. (Inherited from Control) |
| Site |
Gets information about the container that hosts the current control when rendered on a design surface. (Inherited from Control) |
| Size |
Gets or sets the width of the text box in which the file path is entered. |
| SkinID |
Gets or sets the skin to apply to the control. (Inherited from Control) |
| Style |
Gets a collection of all cascading style sheet (CSS) properties applied to a specified HTML server control in the ASP.NET file. (Inherited from HtmlControl) |
| TagName |
Gets the element name of a tag that contains a |
| TemplateControl |
Gets or sets a reference to the template that contains this control. (Inherited from Control) |
| TemplateSourceDirectory |
Gets the virtual directory of the Page or UserControl that contains the current server control. (Inherited from Control) |
| Type |
Gets the type of an HtmlInputControl. (Inherited from HtmlInputControl) |
| UniqueID |
Gets the unique, hierarchically qualified identifier for the server control. (Inherited from Control) |
| ValidateRequestMode |
Gets or sets a value that indicates whether the control checks client input from the browser for potentially dangerous values. (Inherited from Control) |
| Value |
Gets the full path of the file on the client's computer. |
| ViewState |
Gets 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) |
| ViewStateIgnoresCase |
Gets a value that indicates whether the HtmlControl view state is case-sensitive. (Inherited from HtmlControl) |
| ViewStateMode |
Gets or sets the view-state mode of this control. (Inherited from Control) |
| Visible |
Gets or sets a value that indicates whether a server control is rendered as UI on the page. (Inherited from Control) |
Methods
| AddedControl(Control, Int32) |
Called after a child control is added to the Controls collection of the Control object. (Inherited from Control) |
| AddParsedSubObject(Object) |
Notifies 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) |
| ApplyStyleSheetSkin(Page) |
Applies the style properties defined in the page style sheet to the control. (Inherited from Control) |
| BeginRenderTracing(TextWriter, Object) |
Begins design-time tracing of rendering data. (Inherited from Control) |
| BuildProfileTree(String, Boolean) |
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) |
| ClearCachedClientID() |
Sets the cached ClientID value to |
| ClearChildControlState() |
Deletes the control-state information for the server control's child controls. (Inherited from Control) |
| ClearChildState() |
Deletes the view-state and control-state information for all the server control's child controls. (Inherited from Control) |
| ClearChildViewState() |
Deletes the view-state information for all the server control's child controls. (Inherited from Control) |
| ClearEffectiveClientIDMode() |
Sets the ClientIDMode property of the current control instance and of any child controls to Inherit. (Inherited from Control) |
| CreateChildControls() |
Called 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) |
| CreateControlCollection() |
Creates a new ControlCollection object to hold the child controls (both literal and server) of the server control. (Inherited from HtmlControl) |
| DataBind() |
Binds a data source to the invoked server control and all its child controls. (Inherited from Control) |
| DataBind(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) |
| DataBindChildren() |
Binds a data source to the server control's child controls. (Inherited from Control) |
| Dispose() |
Enables a server control to perform final clean up before it is released from memory. (Inherited from Control) |
| EndRenderTracing(TextWriter, Object) |
Ends design-time tracing of rendering data. (Inherited from Control) |
| EnsureChildControls() |
Determines whether the server control contains child controls. If it does not, it creates child controls. (Inherited from Control) |
| EnsureID() |
Creates an identifier for controls that do not have an identifier assigned. (Inherited from Control) |
| Equals(Object) |
Determines whether the specified object is equal to the current object. (Inherited from Object) |
| FindControl(String, Int32) |
Searches the current naming container for a server control with the specified |
| FindControl(String) |
Searches the current naming container for a server control with the specified |
| Focus() |
Sets input focus to a control. (Inherited from Control) |
| GetAttribute(String) |
Gets the value of the named attribute on the HtmlControl control. (Inherited from HtmlControl) |
| GetDesignModeState() |
Gets design-time data for a control. (Inherited from Control) |
| GetHashCode() |
Serves as the default hash function. (Inherited from Object) |
| GetRouteUrl(Object) |
Gets the URL that corresponds to a set of route parameters. (Inherited from Control) |
| GetRouteUrl(RouteValueDictionary) |
Gets the URL that corresponds to a set of route parameters. (Inherited from Control) |
| GetRouteUrl(String, Object) |
Gets the URL that corresponds to a set of route parameters and a route name. (Inherited from Control) |
| GetRouteUrl(String, RouteValueDictionary) |
Gets the URL that corresponds to a set of route parameters and a route name. (Inherited from Control) |
| GetType() |
Gets the Type of the current instance. (Inherited from Object) |
| GetUniqueIDRelativeTo(Control) |
Returns the prefixed portion of the UniqueID property of the specified control. (Inherited from Control) |
| HasControls() |
Determines if the server control contains any child controls. (Inherited from Control) |
| HasEvents() |
Returns a value indicating whether events are registered for the control or any child controls. (Inherited from Control) |
| IsLiteralContent() |
Determines if the server control holds only literal content. (Inherited from Control) |
| LoadControlState(Object) |
Restores control-state information from a previous page request that was saved by the SaveControlState() method. (Inherited from Control) |
| LoadPostData(String, NameValueCollection) |
Processes the postback data for the HtmlInputFile control. |
| LoadViewState(Object) |
Restores view-state information from a previous page request that was saved by the SaveViewState() method. (Inherited from Control) |
| MapPathSecure(String) |
Retrieves the physical path that a virtual path, either absolute or relative, maps to. (Inherited from Control) |
| MemberwiseClone() |
Creates a shallow copy of the current Object. (Inherited from Object) |
| OnBubbleEvent(Object, EventArgs) |
Determines whether the event for the server control is passed up the page's UI server control hierarchy. (Inherited from Control) |
| OnDataBinding(EventArgs) |
Raises the DataBinding event. (Inherited from Control) |
| OnInit(EventArgs) |
Raises the Init event. (Inherited from Control) |
| OnLoad(EventArgs) |
Raises the Load event. (Inherited from Control) |
| OnPreRender(EventArgs) |
Raises the PreRender event for the HtmlInputFile control. |
| OnUnload(EventArgs) |
Raises the Unload event. (Inherited from Control) |
| OpenFile(String) |
Gets a Stream used to read a file. (Inherited from Control) |
| RaiseBubbleEvent(Object, EventArgs) |
Assigns any sources of the event and its information to the control's parent. (Inherited from Control) |
| RaisePostDataChangedEvent() |
Notifies the HtmlInputFile control that the state of the control has changed. |
| RemovedControl(Control) |
Called after a child control is removed from the Controls collection of the Control object. (Inherited from Control) |
| Render(HtmlTextWriter) |
Writes content to render on a client to the specified HtmlTextWriter object. (Inherited from HtmlControl) |
| RenderAttributes(HtmlTextWriter) |
Renders the attributes of the HtmlInputControl control to the specified HtmlTextWriter object. (Inherited from HtmlInputControl) |
| RenderBeginTag(HtmlTextWriter) |
Renders the opening HTML tag of the control into the specified HtmlTextWriter object. (Inherited from HtmlControl) |
| RenderChildren(HtmlTextWriter) |
Outputs 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) |
| RenderControl(HtmlTextWriter, ControlAdapter) |
Outputs server control content to a provided HtmlTextWriter object using a provided ControlAdapter object. (Inherited from Control) |
| RenderControl(HtmlTextWriter) |
Outputs server control content to a provided HtmlTextWriter object and stores tracing information about the control if tracing is enabled. (Inherited from Control) |
| ResolveAdapter() |
Gets the control adapter responsible for rendering the specified control. (Inherited from Control) |
| ResolveClientUrl(String) |
Gets a URL that can be used by the browser. (Inherited from Control) |
| ResolveUrl(String) |
Converts a URL into one that is usable on the requesting client. (Inherited from Control) |
| SaveControlState() |
Saves any server control state changes that have occurred since the time the page was posted back to the server. (Inherited from Control) |
| SaveViewState() |
Saves any server control view-state changes that have occurred since the time the page was posted back to the server. (Inherited from Control) |
| SetAttribute(String, String) |
Sets the value of the named attribute on the HtmlControl control. (Inherited from HtmlControl) |
| SetDesignModeState(IDictionary) |
Sets design-time data for a control. (Inherited from Control) |
| SetRenderMethodDelegate(RenderMethod) |
Assigns an event handler delegate to render the server control and its content into its parent control. (Inherited from Control) |
| SetTraceData(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) |
| SetTraceData(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) |
| ToString() |
Returns a string that represents the current object. (Inherited from Object) |
| TrackViewState() |
Causes tracking of view-state changes to the server control so they can be stored in the server control's StateBag object. This object is accessible through the ViewState property. (Inherited from Control) |
Events
| DataBinding |
Occurs when the server control binds to a data source. (Inherited from Control) |
| Disposed |
Occurs 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) |
| Init |
Occurs when the server control is initialized, which is the first step in its lifecycle. (Inherited from Control) |
| Load |
Occurs when the server control is loaded into the Page object. (Inherited from Control) |
| PreRender |
Occurs after the Control object is loaded but prior to rendering. (Inherited from Control) |
| Unload |
Occurs when the server control is unloaded from memory. (Inherited from Control) |
Explicit Interface Implementations
Extension Methods
| FindDataSourceControl(Control) |
Returns the data source that is associated with the data control for the specified control. |
| FindFieldTemplate(Control, String) |
Returns the field template for the specified column in the specified control's naming container. |
| FindMetaTable(Control) |
Returns the metatable object for the containing data control. |
