[Solved] Combobox GetScriptDescriptors and GetScriptReferences

[lemon]

Hello,

I created a customer control. Based on RadCombobox.

For this control I have to used your workaround http://www.telerik.com/help/aspnet-ajax/back-button-combo-selected-value.html

I add a HiddenControl to my customer class.

Additional I added a js script with GetScriptDescriptors and GetScriptReferences
to implement the js workaround logic.

But it doesn't work.

I add the js on this way:

protected override IEnumerable<ScriptDescriptor> GetScriptDescriptors()
 {
   var desc = base.GetScriptDescriptors().Single() as ScriptControlDescriptor;
   desc.Type = "MyCombobox";
   desc.AddProperty("HiddenFieldId", this.hiddenValueField.ClientID);
  //Note: If I use here AddElementProperty the property in js will be null
   yield return desc;
 }

protected override IEnumerable<ScriptReference> GetScriptReferences()
{
   return base.GetScriptReferences().Concat(this.GetMyScriptReferences());
}

MyCombobox.js
...

OnLoad:
function() {
 this.add_selectedIndexChanged(this._selectItemHandler);
 var savedValue = $get(this._hiddenFieldId).value;
 if (savedValue != "" && this.findItemByValue(savedValue)) {
 this.findItemByValue(savedValue).select();
}

},
...

 

 

In OnLoad this._hiddenFieldId has the correct id, but $get or $find returns NULL.

What is wrong? Have I implement the methods GetScriptDescriptors() and GetScriptReferences() on the right way?

Thanks for support

lemon

 

[Simon]

Hello lemon,

Please make sure that the HiddenField is actually rendered on the page.

You can most easily verify this by inspecting the rendered source of the page and searching for an input type hidden with the same id as comboBox._hiddenFieldId.

Kind regards,
Simon
the Telerik team

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[lemon]

Hello,

thanks for replay.

I verify it and the hiddenfieldid is given. so it seems that the hiddenfield will be rendered correct.

best regards
lemon

[Simon]

Hi lemon,

Did you found in the page rendered HTML an input type hidden with the same ID as the _hiddedFieldId field of the RadComboBox? 

Greetings,
Simon
the Telerik team

Instantly find answers to your questions on the new Telerik Support Portal.
Watch a video on how to optimize your support resource searches and check out more tips on the blogs.

[lemon]

Hello,

yes, I found it

[lemon]

Hi,

I have create a testproject.
Here the code:

using System;
using System.Collections.Generic;
using System.Web;
using Telerik.Web.UI;
using System.Web.UI;
using System.Web.UI.WebControls;

using System.Linq;


namespace MyComboboxProject
{
    [ToolboxData("<{0}:ComboboxWithWorkaround runat=\"server\"> </{0}:ComboboxWithWorkaround>")]
    public class ComboboxWithWorkaround: RadComboBox
    {
        HiddenField hiddenValueField;
        public ComboboxWithWorkaround()
            : base()
        {

        }

        protected override void OnInit(EventArgs e)
        {
            base.OnInit(e);
            hiddenValueField = new HiddenField();
            this.Controls.Add(hiddenValueField);

        }

        private IEnumerable<ScriptReference> GetMyScriptReferences()
        {
            ScriptReference reference = new ScriptReference();
            reference.Assembly = "MyComboboxProject";
            reference.Name = "MyComboboxProject.ComboboxWithWorkaround.js";
            return new ScriptReference[] { reference };
        }

        protected override IEnumerable<ScriptDescriptor> GetScriptDescriptors()
        {
            ScriptControlDescriptor desc = base.GetScriptDescriptors().Single() as ScriptControlDescriptor;
            desc.Type = "MyComboboxProject.ComboboxWithWorkaround";
            desc.AddProperty("HiddenValueField", this.hiddenValueField.ClientID);

            yield return desc;
        }

        protected override IEnumerable<ScriptReference> GetScriptReferences()
        {
            return base.GetScriptReferences().Concat(this.GetMyScriptReferences());
        }

    }
}

the js

/// <reference name="ScriptReferences/jquery-1.3.2-vsdoc.js"/>
Type.registerNamespace("MyComboboxProject");

MyComboboxProject.ComboboxWithWorkaround = function(element) {
MyComboboxProject.ComboboxWithWorkaround.initializeBase(this, [element]);
    this._hiddenValueField = null;
};

MyComboboxProject.ComboboxWithWorkaround.prototype =
{
    initialize: function() {
        this._events = new Sys.EventHandlerList();
        MyComboboxProject.ComboboxWithWorkaround.callBaseMethod(this, 'initialize');

        this._loadHandler = Function.createDelegate(this, this.OnLoad);
        Sys.Application.add_load(this._loadHandler);

        this._selectItemHandler = Function.createDelegate(this, this.OnSelectedItemChangedTest);
    },

    OnLoad: function() {
    debugger
        this.add_selectedIndexChanged(this._selectItemHandler);
        var savedValue = $get(this._hiddenValueField).value;//note $get and $find is null
        if (savedValue != "" && this.findItemByValue(savedValue)) {
            this.findItemByValue(savedValue).select();
        }
    },

    OnSelectedItemChangedTest: function(sender, e) {
        $get(this._hiddenValueField).value = e.get_item().get_value();
    },

    get_HiddenValueField: function() {
    return this._hiddenValueField;
    },

    set_HiddenValueField: function(value) {
    this._hiddenValueField = value;
    }
}

MyComboboxProject.ComboboxWithWorkaround.registerClass('MyComboboxProject.ComboboxWithWorkaround', Telerik.Web.UI.RadComboBox);

if (typeof (Sys) != 'undefined') Sys.Application.notifyScriptLoaded();

Sys.Application.notifyScriptLoaded();

now my customer combobox control, which based on the ComboboWithWorkaround-Control

using System;
using System.Collections.Generic;
using System.Web;
using Telerik.Web.UI;
using System.Web.UI;
using System.Web.UI.WebControls;

using System.Linq;


namespace MyComboboxProject
{
    [ToolboxData("<{0}:MyCustomerCombobox runat=\"server\"> </{0}:MyCustomerCombobox>")]
    public class MyCustomerCombobox : ComboboxWithWorkaround
    {
        public MyCustomerCombobox()
            : base()
        {

        }



        private IEnumerable<ScriptReference> GetMyScriptReferences()
        {
            ScriptReference reference = new ScriptReference();
            reference.Assembly = "MyComboboxProject";
            reference.Name = "MyComboboxProject.MyCustomerCombobox.js";
            return new ScriptReference[] { reference };
        }

        protected override IEnumerable<ScriptDescriptor> GetScriptDescriptors()
        {
            ScriptControlDescriptor desc = base.GetScriptDescriptors().Single() as ScriptControlDescriptor;
            desc.Type = "MyComboboxProject.MyCustomerCombobox";
            yield return desc;
        }

        protected override IEnumerable<ScriptReference> GetScriptReferences()
        {
            return base.GetScriptReferences().Concat(this.GetMyScriptReferences());
        }

    }
}

and the js

/// <reference name="ScriptReferences/jquery-1.3.2-vsdoc.js"/>
Type.registerNamespace("MyComboboxProject");

MyComboboxProject.MyCustomerCombobox = function(element) {
    MyComboboxProject.MyCustomerCombobox.initializeBase(this, [element]);
    this._hiddenValueField = null;
};

MyComboboxProject.MyCustomerCombobox.prototype =
{
    initialize: function() {
    //todo
}
    //todo


}

MyComboboxProject.MyCustomerCombobox.registerClass('MyComboboxProject.MyCustomerCombobox', MyComboboxProject.ComboboxWithWorkaround);

if (typeof (Sys) != 'undefined') Sys.Application.notifyScriptLoaded();

Sys.Application.notifyScriptLoaded();

add these lines to your AssemblyInfo.cs

[assembly: WebResource("MyComboboxProject.ComboboxWithWorkaround.js", "application/x-javascript")]
[assembly: WebResource("MyComboboxProject.MyCustomerCombobox.js", "application/x-javascript")]

best regards
lemon

[lemon]

Hello,

no help, no support for these problem?

regards
lemon

[Simon]

Hello lemon,

Thank you for providing the code.

RadComboBox renders controls added in the Controls collections of its Items only. If you add a control in RadComboBox's Control collection it will not be rendered.

This causes the JavaScript error you are receiving as the client-side script cannot find the hidden field element.

You need to explicitly render the HiddenField control. This you could most conveniently do by overriding the RenderEndTag method of RadComboBox as shown below:

public override void RenderEndTag(HtmlTextWriter writer)
{
    writer.AddAttribute(HtmlTextWriterAttribute.Id, hiddenValueField.ClientID);
        writer.AddAttribute(HtmlTextWriterAttribute.Name, hiddenValueField.ClientID);

        writer.AddAttribute(HtmlTextWriterAttribute.Type, "hidden");

        writer.RenderBeginTag(HtmlTextWriterTag.Input);
        writer.RenderEndTag();

    base.RenderEndTag(writer);
}

The rest of your code you can leave as it is now.

Best wishes,
Simon
the Telerik team

Instantly find answers to your questions on the new Telerik Support Portal.
Watch a video on how to optimize your support resource searches and check out more tips on the blogs.