How to integrate radGrid into a customized webcontrol?

[Liu Peng]

When I integrate radGrid into my customized webcontrol, I meet a error: Script controls may not be registered before PreRender. the following is the source code:
    public class Grid : WebControl, IScriptControl
    {
        // Sub controls
        private RadGrid _radGrid;
        private ScriptManager sm;

        protected override void CreateChildControls()
        {
            Controls.Clear();

            this._radGrid = new RadGrid();
            this._radGrid.NeedDataSource += new GridNeedDataSourceEventHandler(this.radGrid_NeedDataSource);
           
            this.Controls.Add(this._radGrid);

            base.CreateChildControls();
        }

        protected override void OnPreRender(EventArgs e)
        {
            base.OnPreRender(e);
            if (!this.DesignMode)
            {
                // Test for ScriptManager and register if it exists
                sm = ScriptManager.GetCurrent(Page);

                if (sm == null)
                    throw new HttpException("A ScriptManager control must exist on the current page.");

                sm.RegisterScriptControl(this);
            }

        }

        protected void radGrid_NeedDataSource(object source, GridNeedDataSourceEventArgs e)
        {
                try
                {
                    DataTable tbl = new DataTable();
                    ....
                    DataView valuesView = tbl.DefaultView;
                    this._radGrid.DataSource = valuesView;
                }
                catch (Exception ex)
                {
                    System.Diagnostics.Debug.WriteLine(ex.Message);
                }
        }

        #region IScriptControl Members

        public IEnumerable<ScriptDescriptor> GetScriptDescriptors()
        {
            throw new Exception("The method or operation is not implemented.");
        }

        public IEnumerable<ScriptReference> GetScriptReferences()
        {
            throw new Exception("The method or operation is not implemented.");
        }

        #endregion

        #region IScriptControl Members

        IEnumerable<ScriptDescriptor> IScriptControl.GetScriptDescriptors()
        {
            throw new Exception("The method or operation is not implemented.");
        }

        IEnumerable<ScriptReference> IScriptControl.GetScriptReferences()
        {
            throw new Exception("The method or operation is not implemented.");
        }

        #endregion
    }

And then I re-design my webcontrol inherited from RadWebControl, the same error occur.

Server Error in '/' Application.

---

Script controls may not be registered before PreRender.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.InvalidOperationException: Script controls may not be registered before PreRender.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[InvalidOperationException: Script controls may not be registered before PreRender.] System.Web.UI.ScriptControlManager.RegisterScriptControl(TScriptControl scriptControl) +236 System.Web.UI.ScriptManager.RegisterScriptControl(TScriptControl scriptControl) +99 Telerik.Web.UI.RadWebControl.RegisterScriptControl() +60 Telerik.Web.UI.RadWebControl.OnPreRender(EventArgs e) +64 System.Web.UI.Control.PreRenderRecursiveInternal() +86 System.Web.UI.Control.PreRenderRecursiveInternal() +170 System.Web.UI.Control.PreRenderRecursiveInternal() +170 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2041

---

Version Information: Microsoft .NET Framework Version:2.0.50727.1433; ASP.NET Version:2.0.50727.1433

How can I integrate radGrid into my customized webcontrol?

[Giuseppe]

Hello pp,

Could you elaborate how could we reproduce the problematic behavior you are experiencing? We tried to observe the problem with your code but it behaves as expected on our end -- please review the attached sample application and let us know how it goes.


Sincerely yours,
Manuel
the Telerik team

Instantly find answers to your questions at the new Telerik Support Center

[Ron Hary]

Hi,

I have the same scenario (integrated RadGrid) but another problem.
My problem is that the grid does not show in design time...

[Rosen]

Hi Ron,

Can you please provide some more information about your control implementation? Are you using a CompositeControl?

Best regards,
Rosen
the Telerik team

Instantly find answers to your questions at the new Telerik Support Center

[Ron Hary]

    public class Forum : WebControl, INamingContainer
    {
        protected RadGrid _MessageList;

        #region Properties

        #region ParentKeyName

        private string _ParentKeyName = "ParentMessage";

        [DefaultValue( "ParentMessage" )]
        [Category( "Message List" )]
        public string ParentKeyName
        {
            get
            {
                return ( _ParentKeyName );
            }
            set
            {
                _ParentKeyName = value;
            }
        }

        #endregion

        #region KeyName

        private string _KeyName = "ID";

        [DefaultValue( "ID" )]
        [Category( "Message List" )]
        public string KeyName
        {
            get
            {
                return ( _KeyName );
            }
            set
            {
                _KeyName = value;
            }
        }

        #endregion

        #region RootKeyValue

        private string _RootKeyValue = "0";

        [DefaultValue( "0" )]
        [Category( "Message List" )]
        public string RootKeyValue
        {
            get
            {
                return ( _RootKeyValue );
            }
            set
            {
                _RootKeyValue = value;
            }
        }

        #endregion

        #endregion

        #region Helpers

        private void InitGrid ( bool bForDesign )
        {
            // set grid properties
            _MessageList = new RadGrid( );

            _MessageList.ID = "idMessageList";

            _MessageList.ShowHeader = true;
            _MessageList.Visible = true;
            _MessageList.EnableAJAX = true;
            _MessageList.EnableOutsideScripts = true;
            _MessageList.GridLines = GridLines.Horizontal;

            _MessageList.MasterTableView.AutoGenerateColumns = false;

            _MessageList.MasterTableView.DataKeyNames = new string[ ] { _ParentKeyName, _KeyName };
            _MessageList.MasterTableView.FilterExpression = _ParentKeyName + " = " + _RootKeyValue;

            _MessageList.MasterTableView.SelfHierarchySettings.ParentKeyName = _ParentKeyName;
            _MessageList.MasterTableView.SelfHierarchySettings.KeyName = _KeyName;

            Controls.Add( _MessageList );
        }

        #endregion

        #region Render

        protected override void CreateChildControls ( )
        {
            InitGrid( false );

            base.CreateChildControls( );
        }

        protected override void Render ( HtmlTextWriter writer )
        {
            if ( DesignMode )
            {
                InitGrid( true );
            }

            base.Render( writer );
        }

        #endregion
    }

[Rosen]

Hi Ron Hary,

Unfortunately I'm unable to observe this behavior. I have attached a slightly modified version of your code. Can you please give it a try and see if it helps?

Sincerely yours,
Rosen
the Telerik team

Instantly find answers to your questions at the new Telerik Support Center

[Ron Hary]

Thank you