創建一個AJAX腳本控件

Question

打電話給我'n00b'，但我是新創建腳本控件。我想用3個文本框創建一個簡單的控件。我有一個.cs文件，看起來像這樣：

public class SmokingCalc : ScriptControl 
    { 
     public SmokingCalc() 
     { 
      Render(htmlWriter); 
     } 
     protected override void Render(HtmlTextWriter writer) 
     { 
      costTextbox.RenderControl(writer); 
      base.Render(writer); 
     } 
     protected override IEnumerable<ScriptDescriptor> 
       GetScriptDescriptors() 
     { 
      ScriptControlDescriptor descriptor = new ScriptControlDescriptor("SmokingCalc.SmokingCalc", this.ClientID); 
      yield return descriptor; 
     } 

     // Generate the script reference 
     protected override IEnumerable<ScriptReference> 
       GetScriptReferences() 
     { 
      yield return new ScriptReference("SmokingCalc.SmokingCalc.js", this.GetType().Assembly.FullName); 
     } 

     protected HtmlTextWriter htmlWriter; 
     protected TextBox costTextbox; 
     protected TextBox amountTextbox; 
     protected TextBox yearsTextbox; 
     protected Button submitButton; 
    } 
} 

我絕對不知道爲什麼文本框不會渲染？我想我錯過了一些東西...

[編輯]我得到的錯誤是「對象引用沒有設置爲對象的實例」。

[回答]我改變了文件，如下所示，它至少起作用。

public class SmokingCalc : ScriptControl 
    { 
     public SmokingCalc() 
     { 
     } 
     protected override void CreateChildControls() 
     { 
      base.CreateChildControls(); 
      costTextbox.ID = "costTextbox"; 
      amountTextbox.ID = "amountTextbox"; 
      yearsTextbox.ID = "yearsTextbox"; 
      submitButton.ID = "submitButton"; 
      submitButton.Text = "Submit"; 
      Controls.Add(costTextbox); 
      Controls.Add(amountTextbox); 
      Controls.Add(yearsTextbox); 
      Controls.Add(submitButton); 
     } 
     protected override IEnumerable<ScriptDescriptor> 
       GetScriptDescriptors() 
     { 
      ScriptControlDescriptor descriptor = new ScriptControlDescriptor("SmokingCalc.SmokingCalc", this.ClientID); 
      descriptor.AddProperty("costTextboxID", costTextbox.ClientID); 
      descriptor.AddProperty("amountTextboxID", amountTextbox.ClientID); 
      descriptor.AddProperty("yearsTextboxID", amountTextbox.ClientID); 
      descriptor.AddProperty("submitButtonID", submitButton.ClientID); 
      yield return descriptor; 
     } 

     // Generate the script reference 
     protected override IEnumerable<ScriptReference> 
       GetScriptReferences() 
     { 
      yield return new ScriptReference("SmokingCalc.SmokingCalc.js", this.GetType().Assembly.FullName); 
     } 

     protected TextBox costTextbox = new TextBox(); 
     protected TextBox amountTextbox = new TextBox(); 
     protected TextBox yearsTextbox = new TextBox(); 
     protected Button submitButton = new Button(); 
    } 

Answer 1

你嘗試CreateChildControls：

public class SmokingCalc : ScriptControl 
{ 
    protected override void CreateChildControls() 
    { 
     this.Controls.Add(costTextbox); 
    } 

    protected override IEnumerable<ScriptDescriptor> 
      GetScriptDescriptors() 
    { 
     ScriptControlDescriptor descriptor = new ScriptControlDescriptor("SmokingCalc.SmokingCalc", this.ClientID); 
     yield return descriptor; 
    } 

    // Generate the script reference 
    protected override IEnumerable<ScriptReference> 
      GetScriptReferences() 
    { 
     yield return new ScriptReference("SmokingCalc.SmokingCalc.js", this.GetType().Assembly.FullName); 
    } 

    protected HtmlTextWriter htmlWriter; 
    protected TextBox costTextbox = new TextBox(); 
    protected TextBox amountTextbox = new TextBox(); 
    protected TextBox yearsTextbox = new TextBox(); 
    protected Button submitButton = new Button(); 
} 

Answer 2

你在做什麼這裏正在建設一個複合控件，而不是一個腳本控制，本身。您真正想要做的是繼承CompositeControl（and following the model for creating a composite control），並實施IScriptControl。你需要用很多方法來解決這個問題（ViewState和回發問題等）。