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Asp.NET Core Server Controls. Lecture Overview. Understanding the types of ASP.NET controls HTML controls ASP.NET (Web) controls. The runat Attribute. The runat attribute makes a server control a server control This is true for both HTML and Web controls
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Lecture Overview • Understanding the types of ASP.NET controls • HTML controls • ASP.NET (Web) controls
The runat Attribute • The runat attribute makes a server control a server control • This is true for both HTML and Web controls • All tags without the runat attribute set are copied verbatim to the output stream (HTTP response) • <asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>
Categorizing Server Controls ASP.NET CONTROLS WEB CONTROLS HTML CONTROLS
Categorizing Server Controls • HTML controls • always map to HTML tags • All attributes are strictly compatible with XHTML • They allow you to perform ‘some’ server side processing • Web Controls (ASP.NET server controls) • Are implemented by the ASP server as .NET Framework classes having a common .NET programming interface
Generalities • HTML controls and Web controls can sometimes to do the same thing • HTML controls can be used to conditionally create client-side script • Web controls generally provide a ‘richer’ programmatic interface
HTML Controls (Example <head>) • A <head> tag can be designated runat=“server” • The Header property maps to the HTML <head> tag • <head runat="server">
HTML Controls (Example <head>) • Store a value in the page header protected void Page_Load(object sender, EventArgs e) { Header.Title = "IS 460 HTML Control Demo " + System.DateTime.Now.ToString(); }
HTML Controls (Example <head>) • The following <head> tag is emitted from the server-side control <head> <title> IS 460 HTML Control Demo 9/7/2009 12:09:10 PM </title> </head>
HTML Controls <a> • The HTMLAnchorclass implements <a> tags • <a> tags designated runat=“server” and having an id will be seen by the server <a id="BusinessNews" runat="server"></a>
ASP.NET Server Controls • These are unique to ASP.NET • All are contained in the System.Web.UI.WebControls namespace • All derive from WebControl • runat=“server” attribute is required or the markup will be rendered verbatim • They are not the same as HTML controls • The programming interface is more intuitive
ASP.NET Server Controls (Properties 1) • ID – Name that will be used to reference the control instance programmatically • Page – Page object on which the control resides • Parent – parent control instance • Visible – Make the control instance visible or invisible • EnableViewState defines whether contents are persisted through view state
ASP.Net Server Controls (Properties 2) • The Style property contains references a collection of CSS style MyControlStyle[“border-color”] = blue; • The CssClass contains the name of a defined CSS class • txtStyleDemo1.CssClass = "TextBox"
ASP.NET Server Controls(Methods) • Focus – sets input focus to the control instance when it is rendered • HasControls – denotes whether this control instance has child controls • Controls – a collection of child controls • DataBind – binds the control instance to a data source
ASP.NET Server Controls (Events) • Same page and control events discussed in the previous chapter • Init – First step in the life cycle • Load – occurs when the control is loaded into the page • PreRender – fires just before the page is rendered • Unload – control has been rendered. Use only to close files or release connections
Other Control Characteristics • Adaptive rendering allows controls to render differently based on the browser • Control properties can be declared for different browsers, as follows: <asp:TextBox ID="TextBox4" runat="server" ie:text="IE Button" mozilla:text="Firefox button"></asp:TextBox>
Control State (Introduction) • State information must often be persisted across page requests • Control state is like view state • You generally don’t mess with the control state
Core Web Controls (Introduction) • Editable controls include check boxes, radio buttons, text boxes, labels, etc… • There is a Table control that implements a table container • TableCell and TableRow implement cells and rows • See Demo • HyperLink and LinkButton implement links • Use the FileUpload control to upload files
Button Controls (Introduction) • CausesValidation determines whether a validation is performed when the button is clicked. ValidationGroup also controls validation • More next time • Text contains the text that appears in the button • Visible property displays or hides the button
Other Controls • The Panel control acts as a container for other controls • The View control creates a group of interchangeable panels