RadTreeList in the DynamicData ManyToMany_Edit.ascx Control

[Scott Morrison]

When using the RadTreeList in the DynamicData ManyToMany_Edit.ascx control, I am getting the following null ref error:

[NullReferenceException: Object reference not set to an instance of an object.] Telerik.Web.UI.TreeListItemDecorator.PrepareDataItemsServiceCells(RadTreeList owner) +534 Telerik.Web.UI.RadTreeList.PrepareRows() +215 Telerik.Web.UI.RadTreeList.Render(HtmlTextWriter writer) +29 System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +27 System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +100 System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +25 System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) +208 System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) +8 System.Web.UI.Control.Render(HtmlTextWriter writer) +10 System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +27 System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +100 System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +25 System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) +208 System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) +8 System.Web.DynamicData.DynamicControl.Render(HtmlTextWriter writer) +154 ...

Here is the code:

 

<%@ Control Language="C#" CodeBehind="ManyToMany_Edit.ascx.cs" Inherits="Ctp.U.Web.ResidentPortal.Forms.ManyToMany_EditField" %>
<%@ Register Assembly="Telerik.Web.UI" Namespace="Telerik.Web.UI" TagPrefix="telerik" %>

<telerik:RadTreeList ID="_radTreeList1" runat="server" OnDataBound="_radTreeList1_DataBound">
</telerik:RadTreeList>

using System;
using System.Collections;
using System.ComponentModel;
using System.Data.Objects;
using System.Data.Objects.DataClasses;
using System.Web.DynamicData;
using System.Web.UI;
using System.Web.UI.WebControls;
using Telerik.Web.UI;

namespace Ctp.U.Web.ResidentPortal.Forms
{
    public partial class ManyToMany_EditField : System.Web.DynamicData.FieldTemplateUserControl
    {
        public void Page_Load(object sender, EventArgs e)
        {
            // Register for the DataSource's updating event
            EntityDataSource ds = (EntityDataSource)this.FindDataSourceControl();

            // This field template is used both for Editing and Inserting
            ds.Updating += new EventHandler<EntityDataSourceChangingEventArgs>(DataSource_UpdatingOrInserting);
            ds.Inserting += new EventHandler<EntityDataSourceChangingEventArgs>(DataSource_UpdatingOrInserting);
        }

        void DataSource_UpdatingOrInserting(object sender, EntityDataSourceChangingEventArgs e)
        {
            MetaTable childTable = ChildrenColumn.ChildTable;

            // Comments assume employee/territory for illustration, but the code is generic

            // Get the collection of territories for this employee
            RelatedEnd entityCollection = (RelatedEnd)Column.EntityTypeProperty.GetValue(e.Entity, null);

            // In Edit mode, make sure it's loaded (doesn't make sense in Insert mode)
            if (Mode == DataBoundControlMode.Edit && !entityCollection.IsLoaded)
            {
                entityCollection.Load();
            }

            // Get an IList from it (i.e. the list of territories for the current employee)
            // REVIEW: we should be using EntityCollection directly, but EF doesn't have a
            // non generic type for it. They will add this in vnext
            IList entityList = ((IListSource)entityCollection).GetList();

            // Go through all the territories (not just those for this employee)
            foreach (object childEntity in childTable.GetQuery(e.Context))
            {

                // Check if the employee currently has this territory
                bool isCurrentlyInList = entityList.Contains(childEntity);

                // Find the checkbox for this territory, which gives us the new state
                string pkString = childTable.GetPrimaryKeyString(childEntity);
                //ListItem listItem = CheckBoxList1.Items.FindByValue(pkString);
                TreeListDataItem radItem = null;

                foreach (TreeListDataItem item in _radTreeList1.Items)
                {
                    if (item["Id"].Text == pkString)
                        radItem = item;
                }

                if (radItem == null)
                    continue;

                // If the states differs, make the appropriate add/remove change
                if (radItem.Selected)
                {
                    if (!isCurrentlyInList)
                        entityList.Add(childEntity);
                }
                else
                {
                    if (isCurrentlyInList)
                        entityList.Remove(childEntity);
                }
            }
        }

        protected void DataBound()
        {
            MetaTable childTable = ChildrenColumn.ChildTable;

            // Comments assume employee/territory for illustration, but the code is generic

            IList entityList = null;
            ObjectContext objectContext = null;

            if (Mode == DataBoundControlMode.Edit)
            {
                object entity;
                ICustomTypeDescriptor rowDescriptor = Row as ICustomTypeDescriptor;
                if (rowDescriptor != null)
                {
                    // Get the real entity from the wrapper
                    entity = rowDescriptor.GetPropertyOwner(null);
                }
                else
                {
                    entity = Row;
                }

                // Get the collection of territories for this employee and make sure it's loaded
                RelatedEnd entityCollection = Column.EntityTypeProperty.GetValue(entity, null) as RelatedEnd;
                if (entityCollection == null)
                {
                    throw new InvalidOperationException(String.Format("The ManyToMany template does not support the collection type of the '{0}' column on the '{1}' table.", Column.Name, Table.Name));
                }
                if (!entityCollection.IsLoaded)
                {
                    entityCollection.Load();
                }

                // Get an IList from it (i.e. the list of territories for the current employee)
                // REVIEW: we should be using EntityCollection directly, but EF doesn't have a
                // non generic type for it. They will add this in vnext
                entityList = ((IListSource)entityCollection).GetList();

                // Get the current ObjectContext
                // REVIEW: this is quite a dirty way of doing this. Look for better alternative
                ObjectQuery objectQuery = (ObjectQuery)entityCollection.GetType().GetMethod(
                    "CreateSourceQuery").Invoke(entityCollection, null);
                objectContext = objectQuery.Context;
            }

            // Go through all the territories (not just those for this employee)
            foreach (object childEntity in childTable.GetQuery(objectContext))
            {
                _radTreeList1.DataKeyNames = new string[] { "Id" };
                _radTreeList1.ParentDataKeyNames = new string[] { "ParentId" };

                TreeListDataItem radItem = new TreeListDataItem(_radTreeList1
                    , TreeListItemType.Item
                    , _radTreeList1.Items.Count
                    , true);

                radItem.DataItem = childEntity;

                // Make it selected if the current employee has that territory
                if (Mode == DataBoundControlMode.Edit)
                {
                    radItem.Selected = entityList.Contains(childEntity);
                }

                _radTreeList1.Items.Add(radItem);
            }
        }

        protected void _radTreeList1_DataBound(object sender, EventArgs e)
        {
            DataBound();
        }

        public override Control DataControl
        {
            get
            {
                return _radTreeList1;
            }
        }

    }
}

[Scott Morrison]

I've got it all working using a different approach. Very nice. Not very generic at this point but it would not take much to make it so. The solution is below.

I would still like to know why the first approach threw the error. Anyone have any ideas?

Here is the working solution using a different approach.

<%@ Control Language="C#" CodeBehind="ManyToMany_Edit.ascx.cs" Inherits="Ctp.U.Web.ResidentPortal.Forms.ManyToMany_EditField" %>
<%@ Register Assembly="Telerik.Web.UI" Namespace="Telerik.Web.UI" TagPrefix="telerik" %>

<telerik:RadAjaxPanel ID="_radAjaxPanel" runat="server">
    <telerik:RadTreeList ID="_radTreeList" runat="server" DataKeyNames="Id" ParentDataKeyNames="ParentId"
        AutoGenerateColumns="False" DataSourceID="_entityDataSource" AllowMultiItemSelection="True"
        AllowMultiItemEdit="False" Culture="(Default)" IsItemInserted="False" AllowRecursiveSelection="true"
        OnDataBound="_radTreeList_DataBound" OnItemCommand="_radTreeList_ItemCommand" >
        <ClientSettings AllowPostBackOnItemClick="true"></ClientSettings>
        <ValidationSettings CommandsToValidate="PerformInsert,Update" />
        <Columns>
            <telerik:TreeListBoundColumn DataField="Name" HeaderText="Name"
                UniqueName="Name">
            </telerik:TreeListBoundColumn>
            <telerik:TreeListSelectColumn HeaderStyle-Width="50px">
            </telerik:TreeListSelectColumn>
        </Columns>
    </telerik:RadTreeList>
</telerik:RadAjaxPanel>
<asp:EntityDataSource ID="_entityDataSource" runat="server" ConnectionString="name=WashUResidentPortalEntities"
    DefaultContainerName="WashUResidentPortalEntities" EnableFlattening="False" EntitySetName="Organizations">
</asp:EntityDataSource>

 

using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data.Objects.DataClasses;
using System.Web.DynamicData;
using System.Web.UI;
using System.Web.UI.WebControls;
using Telerik.Web.UI;

namespace Ctp.U.Web.ResidentPortal.Forms
{
    public partial class ManyToMany_EditField : System.Web.DynamicData.FieldTemplateUserControl
    {
        List<string> _selectedKeys;

        public void Page_Load(object sender, EventArgs e)
        {
            // Register for the DataSource's updating event
            EntityDataSource ds = (EntityDataSource)this.FindDataSourceControl();

            // This field template is used both for Editing and Inserting
            ds.Updating += new EventHandler<EntityDataSourceChangingEventArgs>(DataSource_UpdatingOrInserting);
            ds.Inserting += new EventHandler<EntityDataSourceChangingEventArgs>(DataSource_UpdatingOrInserting);

            if (string.IsNullOrEmpty(_entityDataSource.EntitySetName))
                _entityDataSource.EntitySetName = ChildrenColumn.ChildTable.Name;
            _selectedKeys = ViewState["_selectedKeys"] as List<string>;
        }

        protected void _radTreeList_ItemCommand(object sender, TreeListCommandEventArgs e)
        {
            switch (e.CommandName)
            {
                case "ExpandCollapse":
                    break;
                case "Deselect":
                    e.ExecuteCommand(sender);
                    RemoveSelections();
                    break;
                case "Select":
                    e.ExecuteCommand(sender);
                    break;
                case "ItemClick":
                    e.ExecuteCommand(sender);
                    TreeListDataItem item = e.Item as TreeListDataItem;
                    item.Selected = !item.Selected;
                    RemoveSelections();
                    break;
            }
        }

        protected void _radTreeList_DataBound(object sender, EventArgs e)
        {
            DataBound();
        }

        protected override void OnDataBinding(EventArgs e)
        {
            base.OnDataBinding(e);
            GetSelections();
            _radTreeList.ExpandAllItems();
        }

        void DataSource_UpdatingOrInserting(object sender, EntityDataSourceChangingEventArgs e)
        {
            MetaTable childTable = ChildrenColumn.ChildTable;

            // Comments assume employee/territory for illustration, but the code is generic

            // Get the collection of territories for this employee
            RelatedEnd entityCollection = (RelatedEnd)Column.EntityTypeProperty.GetValue(e.Entity, null);

            // In Edit mode, make sure it's loaded (doesn't make sense in Insert mode)
            if (Mode == DataBoundControlMode.Edit && !entityCollection.IsLoaded)
            {
                entityCollection.Load();
            }

            // Get an IList from it (i.e. the list of territories for the current employee)
            // REVIEW: we should be using EntityCollection directly, but EF doesn't have a
            // non generic type for it. They will add this in vnext
            IList entityList = ((IListSource)entityCollection).GetList();

            // Go through all the territories (not just those for this employee)
            foreach (object childEntity in childTable.GetQuery(e.Context))
            {

                // Check if the employee currently has this territory
                bool isCurrentlyInList = entityList.Contains(childEntity);

                // Find the checkbox for this territory, which gives us the new state
                string pkString = childTable.GetPrimaryKeyString(childEntity);
                //ListItem listItem = CheckBoxList1.Items.FindByValue(pkString);
                TreeListDataItem radItem = null;

                foreach (TreeListDataItem item in _radTreeList.Items)
                {
                    if (item.GetDataKeyValue(_radTreeList.DataKeyNames[0]).ToString() == pkString)
                    {
                        radItem = item;
                        break;
                    }
                }

                if (radItem == null)
                    continue;

                // If the states differs, make the appropriate add/remove change
                if (radItem.Selected)
                {
                    if (!isCurrentlyInList)
                        entityList.Add(childEntity);
                }
                else
                {
                    if (isCurrentlyInList)
                        entityList.Remove(childEntity);
                }
            }
        }

        void GetSelections()
        {
            if (Mode == DataBoundControlMode.Edit && _selectedKeys == null)
            {
                MetaTable childTable = ChildrenColumn.ChildTable;
                IList entityList;
                // Comments assume employee/territory for illustration, but the code is generic

                object entity;
                ICustomTypeDescriptor rowDescriptor = Row as ICustomTypeDescriptor;
                if (rowDescriptor != null)
                {
                    // Get the real entity from the wrapper
                    entity = rowDescriptor.GetPropertyOwner(null);
                }
                else
                {
                    entity = Row;
                }

                // Get the collection of territories for this employee and make sure it's loaded
                RelatedEnd entityCollection = Column.EntityTypeProperty.GetValue(entity, null) as RelatedEnd;
                if (entityCollection == null)
                {
                    throw new InvalidOperationException(String.Format("The ManyToMany template does not support the collection type of the '{0}' column on the '{1}' table.", Column.Name, Table.Name));
                }
                if (!entityCollection.IsLoaded)
                {
                    entityCollection.Load();
                }

                // Get an IList from it (i.e. the list of territories for the current employee)
                // REVIEW: we should be using EntityCollection directly, but EF doesn't have a
                // non generic type for it. They will add this in vnext
                entityList = ((IListSource)entityCollection).GetList();
                _selectedKeys = new List<string>();
                foreach (object selected in entityList)
                    _selectedKeys.Add((selected as System.Data.Objects.DataClasses.EntityObject).EntityKey.EntityKeyValues[0].Value.ToString());
                ViewState["_selectedKeys"] = _selectedKeys;
            }
        }

        protected void DataBound()
        {
            if (Mode == DataBoundControlMode.Edit && _selectedKeys.Count > 0)
            {
                foreach (TreeListDataItem radItem in _radTreeList.Items)
                {
                    if (_selectedKeys.Contains(GetRadTreeItemKey(radItem)))
                        radItem.Selected = true;
                }
            }
        }

        void RemoveSelections()
        {
            if (Mode == DataBoundControlMode.Edit && _selectedKeys.Count > 0)
            {
                foreach (TreeListDataItem radItem in _radTreeList.Items)
                {
                    if (!radItem.Selected)
                        _selectedKeys.Remove(GetRadTreeItemKey(radItem));
                }
            }
        }

        string GetRadTreeItemKey(TreeListDataItem radItem)
        {
            return radItem.GetDataKeyValue(_radTreeList.DataKeyNames[0]).ToString();
        }

        public override Control DataControl
        {
            get
            {
                return _radTreeList;
            }
        }

    }
}

[Radoslav]

Hi Scott,

I am glad that you achieved the desired functionality. Additionally please keep in mind that RadTreeList does not support directly adding items into its Items collection. The RadTreeList is a bound controls and to be properly bound it needs a collection of data items to be passed to its DataSource property or DataSource control. More information you could find on the following resources:
http://www.telerik.com/help/aspnet-ajax/treelist-simple-vs-advanced-binding.html
http://www.telerik.com/help/aspnet-ajax/treelist-net35-data-source-controls.html

Best wishes,
Radoslav
the Telerik team