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Editor to share with you the example analysis of single-select and multi-select controls in Asp.net custom controls. I hope you will get something after reading this article. Let's discuss it together.

The details are as follows

It is also a good choice to package commonly used jquery plug-ins into controls.

Let's see the effect first:

1. Create a new class library project and create a data source class

Public class Select2Item {public bool Selected {get; set;} public string Text {get; set;} public string Value {get; set;} public Select2Item () {} public Select2Item (string text, string value) {this.Text = text; this.Value = value;} public Select2Item (string text, string value, bool selected) {this.Text = text; this.Value = value; this.Selected = selected;}}

two。 Create a control class CheckList, inherit from WebControl, and define public List Items data item properties.

3. Introduce script files and style files

a. Create a script or style file, set the properties of the file-generate operations-embedded resources

b. You need to add the tag [assembly: WebResource ("Namespace. Folder name. file name", "mime type")] to the namespace

Such as:

[assembly: WebResource ("Control.Style.checklist.css", "text/css", PerformSubstitution = true)]

[assembly: WebResource ("Control.Scripts.checklist.js", "application/x-javascript")]

If there is a picture in the css file, the picture is also set to the embedded resource, which is written as follows in css

PerformSubstitution indicates whether the URL of other Web resources is analyzed during the processing of embedded resources and replaced with the full path of that resource.

c. Rewrite protected override void OnPreRender (EventArgs e) to introduce embedded scripts or style files

If (paginated null) Page.Header.Controls.Add (LiteralControl), put the tag in LiteralControl, then add LiteralControl to Page.Header, and finally you will see the introduced tag on the page.

Protected override void OnPreRender (EventArgs e) {if (this.Page! = null) {StringBuilder sbb = new StringBuilder (); sbb.Append (string.Format (STYLE_TEMPLATE, Page.ClientScript.GetWebResourceUrl (this.GetType (), "HandControl.Style.checklist.css"); sbb.Append (string.Format (SCRIPT_TEMPLATE, Page.ClientScript.GetWebResourceUrl (this.GetType (), "HandControl.Scripts.checklist.js")); bool hascss = false; LiteralControl lcc = new LiteralControl (sbb.ToString ()) Lcc.ID = "lccheck"; foreach (Control item in Page.Header.Controls) {if (item.ID = = "lccheck") hascss = true;} if (! hascss) Page.Header.Controls.Add (lcc);} base.OnPreRender (e);}

4. Override the protected override void Render (HtmlTextWriter writer) method of a control

This is mainly the html of the rendering control, depending on your control.

Protected override void Render (HtmlTextWriter writer) {if (Items.Count > 0) {writer.Write (""); if (Multiple = = false) writer.Write (""); else writer.Write (""); bool first = true; foreach (var item in Items) {if (Multiple = = false) {if (item.Selected & first) {writer.Write ("" + item.Text + "); first = false } else {writer.Write ("" + item.Text + ");}} else {if (item.Selected) writer.Write ("+ item.Text +"); else writer.Write ("" + item.Text + "");}} writer.Write ("");}}

5. Add GetSelected method, return List, add GetSelectValue, return String (separated by multiple selections)

Public List GetSelected () {if (Page! = null) {var values = Page.Request.Form ["tb" + this.ClientID] .split (','); var res = Items.Where (t = > values.Contains (t.Value)). ToList (); foreach (var item in Items) {if (res.Contains (item)) {item.Selected = true;} else {item.Selected = false;} return res;} else {return null }} public string GetSelectValue () {if (Page! = null) {return Page.Request.Form ["tb" + this.ClientID];} return "";}

6. Save statu

You need to override two methods, protected override object SaveViewState () and protected override void LoadViewState (object savedState), to save Items data item properties to ViewState

Protected override object SaveViewState () {var valuestr = Page.Request.Form ["tb" + this.ClientID]; if (! string.IsNullOrEmpty (valuestr)) {var values = valuestr.Split (','); var temp = Items.Where (t = > values.Contains (t.Value)). ToList (); foreach (var item in temp) {item.Selected = true;}} return new object [] {base.SaveViewState (), Items} } protected override void LoadViewState (object savedState) {object [] vState = (object []) savedState; if (vState [0]! = null) base.LoadViewState (vState [0]); if (vState [1]! = null) Items = (List) vState [1];}

7. Radio and check settings, controlled in js

Add attribute

[Description ("get and set multiple selections"), DefaultValue (true), Browsable (true), Category ("miscellaneous")]

Public bool Multiple {get; set;}

In the OnPreRender code, you will find that the Multiple attribute will affect the value of the mul attribute of div, thus determining whether to select multiple selections (default multiple selections).

8. Other instructions

Private static readonly string STYLE_TEMPLATE = "\ r\ n"

Private static readonly string SCRIPT_TEMPLATE = "\ r\ n"

Effect picture:

After reading this article, I believe you have a certain understanding of "sample analysis of single-select and multi-select controls in Asp.net custom controls". If you want to know more about it, welcome to follow the industry information channel, thank you for reading!

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