Asp.NET Core Server Controls

Slide 2 Lecture Overview Understanding the types of ASP.NET controls HTML controls ASP.NET (Web) controls

Slide 3 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)

Slide 4 Categorizing Server Controls ASP.NET CONTROLS HTML CONTROLS WEB CONTROLS

Slide 5 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

Slide 6 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

Slide 7 HTML Controls (Example ) A tag can be designated runat=“server” The Header property maps to the HTML tag

Slide 8 HTML Controls (Example ) 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(); }

Slide 9 HTML Controls (Example ) The following tag is emitted from the server-side control IS 460 HTML Control Demo 9/7/ :09:10 PM

Slide 10 HTML Controls The HTMLAnchor class implements tags tags designated runat=“server” and having an id will be seen by the server

Slide 11 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

Slide 12 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

Slide 13 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"

Slide 14 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

Slide 15 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

Slide 16 Other Control Characteristics Adaptive rendering allows controls to render differently based on the browser Control properties can be declared for different browsers, as follows:

Slide 17 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

Slide 18 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

Slide 19 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

Slide 20 Other Controls The Panel control acts as a container for other controls The View control creates a group of interchangeable panels