CompositeControl and order of LoadPostData

Question

User-1643923816 posted

Hello Guys,

I have a kind of philosophical question about control creation.

Let's imagine you have the following scenario :

• A CompositeControl composed of a TextBox (let's name it SuperTextBox)
  • for a more realistic scenario, let's imagine this is a control including validation, AJAX stuff like AjaxControlToolkit controls, ...
• Another CompositeControl composed of several "SuperTextBox" (let's name is MyContainer)

So typically, here is how my SuperTextBox would look like :

   public class SuperTextBox : CompositeControl
   {
      private TextBox txt;

      public string Text 
      {
         get
         {
            this.EnsureChildControls();
            return this.txt.Text + "Super";
         }
         set
         {
            this.EnsureChildControls();
            this.txt.Text = value + "Super";
         }
      }

      protected override void CreateChildControls()
      {
         base.CreateChildControls();
         this.txt = new TextBox() { ID = "txt" };
         this.Controls.Add(this.txt);
      }
   }

What do you think of this implementation ? Here, I do not want to implement IPostBackDataHandler (well at least I do not think it's necessary) as all my loading stuff is done by the internal TextBox. Do you agree with me so far ?

So what I want to do now is to create the MyContainer control which will be the editor of a simple class. Let's take for example :

   [Serializable]

   public class MyObject
   {
      public string Name { get; set; }
      public string FirstName { get; set; }
   }

So my feeling is that the MyContainer control should hold a property storing in the view state this object, and that this one should implement IPostBackDataHandler to fill it (if necessary).

So I would suggest something like :

   public class MyContainer : CompositeControl, IPostBackDataHandler
   {
      private SuperTextBox txtName;
      private SuperTextBox txtFirstName;

      public MyObject Object
      {
         get { return (MyObject)ViewState["Object"]; }
         set { ViewState["Object"] = value; }
      }

      protected override void CreateChildControls()
      {
         base.CreateChildControls();

         this.txtName = new SuperTextBox() { ID = "txtName" };
         this.Controls.Add(this.txtName);

         this.txtFirstName = new SuperTextBox() { ID = "txtFirstName" };
         this.Controls.Add(this.txtFirstName);
      }

      protected override void OnPreRender(EventArgs e)
      {
         base.OnPreRender(e);
         this.Page.RegisterRequiresPostBack(this);

         this.txtName.Text = this.Object.Name;
         this.txtFirstName.Text = this.Object.FirstName;
      }

      #region IPostBackDataHandler Members

      bool IPostBackDataHandler.LoadPostData(string postDataKey, NameValueCollection postCollection)
      {
         /* We want here to update the property with the newly posted value
          * Each control having its own mechanism for loading its postdata, we shall rely here
          * on the child control's properties
          */
         this.EnsureChildControls();
         this.Object.Name = this.txtName.Text;
         this.Object.FirstName = this.txtFirstName.Text;
         return true;
      }

      void IPostBackDataHandler.RaisePostDataChangedEvent()
      {
         //No Event to raise
      }

      #endregion
   }

Here as I want to update my object, I implement the IPostBackDataHandler and I load my object with the new values. As my child control are already responsible of loading / validating / transforming their data, I do not want to load from postCollection, but really from my child controls.

That's why I do "EnsureChildControls".

However, we have no control - as far as I know - about the order into which the LoadPostData will be called. So there is a risk that when the MyContainer's LoadPostData method will be called, the TextBox's LoadPostData will not be called yet.

As a result, I do not have the value.

 

My question is "simple". What would you do ? Just some hints about my "specifications"

• There are many validation / transformation / computation done in my SuperTextBox and so it should be responsible of loading its data from the post collection (do you agree ?)
• I do not really want to do a DataboundControl (am I wrong ?) as they work as "fire and forget" and thus I should handle many events to get back the updated values
• The solution I propose will increase the view state size but this is acceptable in my scenario where I will edit almost (99%) all the fields of MyObject via MyContainer.

What do you think ?