ObjectViewEntityCollectionData.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / Net / Net / 3.5.50727.3053 / DEVDIV / depot / DevDiv / releases / Orcas / SP / ndp / fx / src / DataEntity / System / Data / Objects / ObjectViewEntityCollectionData.cs / 1 / ObjectViewEntityCollectionData.cs
                        

                        
                            //---------------------------------------------------------------------- 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// 
// @owner       jhutson
// @backupOwner [....] 
//--------------------------------------------------------------------- 
using System;
using System.Collections.Generic; 
using System.ComponentModel;
using System.Data.Objects.DataClasses;
using System.Diagnostics;
 
namespace System.Data.Objects
{ 
    ///  
    /// Manages a binding list constructed from an EntityCollection.
    ///  
    /// 
    /// Type of the elements in the binding list.
    /// 
    ///  
    /// Type of element in the underlying EntityCollection.
    ///  
    ///  
    /// The binding list is initialized from the EntityCollection,
    /// and is synchronized with changes made to the EntityCollection membership. 
    /// This class always allows additions and removals from the binding list.
    /// 
    internal sealed class ObjectViewEntityCollectionData : IObjectViewData
        where TItemElement : class, IEntityWithRelationships 
        where TViewElement : TItemElement
    { 
        private List _bindingList; 

        private EntityCollection _entityCollection; 

        private readonly bool _canEditItems;

        ///  
        /// True if item that was added to binding list but not underlying entity collection
        /// is now being committed to the collection. 
        /// Otherwise false. 
        /// Used by CommitItemAt and OnCollectionChanged methods to coordinate addition
        /// of new item to underlying entity collection. 
        /// 
        private bool _itemCommitPending;

        ///  
        /// Construct a new instance of the ObjectViewEntityCollectionData class using the supplied entityCollection.
        ///  
        ///  
        /// EntityCollection used to populate the binding list.
        ///  
        internal ObjectViewEntityCollectionData(EntityCollection entityCollection)
        {
            _entityCollection = entityCollection;
 
            _canEditItems = typeof(IEntityWithChangeTracker).IsAssignableFrom(typeof(TViewElement));
 
            _bindingList = new List(entityCollection.Count); 
            foreach (TViewElement entity in entityCollection)
            { 
                _bindingList.Add(entity);
            }
        }
 
        #region IObjectViewData Members
 
        public IList List 
        {
            get { return _bindingList; } 
        }

        public bool AllowNew
        { 
            get { return !_entityCollection.IsReadOnly; }
        } 
 
        public bool AllowEdit
        { 
            get { return _canEditItems; }
        }

        public bool AllowRemove 
        {
            get { return !_entityCollection.IsReadOnly; } 
        } 

        public bool FiresEventOnAdd 
        {
            get { return true; }
        }
 
        public bool FiresEventOnRemove
        { 
            get { return true; } 
        }
 
        public bool FiresEventOnClear
        {
            get { return true; }
        } 

        public void EnsureCanAddNew() 
        { 
            // nop
        } 

        public int Add(TViewElement item, bool isAddNew)
        {
            if (isAddNew) 
            {
                // Item is added to bindingList, but pending addition to entity collection. 
                _bindingList.Add(item); 
            }
            else 
            {
                _entityCollection.Add(item);
                // OnCollectionChanged will be fired, where the binding list will be updated.
            } 

            return _bindingList.Count - 1; 
        } 

        public void CommitItemAt(int index) 
        {
            TViewElement item = _bindingList[index];

            try 
            {
                _itemCommitPending = true; 
 
                _entityCollection.Add(item);
                // OnCollectionChanged will be fired, where the binding list will be updated. 
            }
            finally
            {
                _itemCommitPending = false; 
            }
 
        } 

        public void Clear() 
        {
            if (0 < _bindingList.Count)
            {
                List _deletionList = new List(); 

                foreach (object item in _bindingList) 
                { 
                    _deletionList.Add(item as IEntityWithRelationships);
                } 

                _entityCollection.BulkDeleteAll(_deletionList);
                // EntityCollection will fire change event which this instance will use to clean up the binding list.
            } 
        }
 
        public bool Remove(TViewElement item, bool isCancelNew) 
        {
            bool removed; 

            if (isCancelNew)
            {
                // Item was previously added to binding list, but not entity collection. 
                removed = _bindingList.Remove(item);
            } 
            else 
            {
                removed = _entityCollection.Remove(item); 
                // OnCollectionChanged will be fired, where the binding list will be updated.
            }

            return removed; 
        }
 
        public ListChangedEventArgs OnCollectionChanged(object sender, CollectionChangeEventArgs e, ObjectViewListener listener) 
        {
            ListChangedEventArgs changeArgs = null; 

            switch (e.Action)
            {
                case CollectionChangeAction.Remove: 
                    // An Entity is being removed from entity collection, remove it from list.
                    if (e.Element is TViewElement) 
                    { 
                        TViewElement removedItem = (TViewElement)e.Element;
 
                        int oldIndex = _bindingList.IndexOf(removedItem);
                        if (oldIndex != -1)
                        {
                            _bindingList.Remove(removedItem); 

                            // Unhook from events of removed entity. 
                            listener.UnregisterEntityEvents(removedItem); 

                            changeArgs = new ListChangedEventArgs(ListChangedType.ItemDeleted, oldIndex /* newIndex*/, -1 /* oldIndex*/); 
                        }
                    }
                    break;
 
                case CollectionChangeAction.Add:
                    // Add the entity to our list. 
                    if (e.Element is TViewElement) 
                    {
                        // Do not process Add events that fire as a result of committing an item to the entity collection. 
                        if (!_itemCommitPending)
                        {
                            TViewElement addedItem = (TViewElement)e.Element;
 
                            _bindingList.Add(addedItem);
 
                            // Register to its events. 
                            listener.RegisterEntityEvents(addedItem);
 
                            changeArgs = new ListChangedEventArgs(ListChangedType.ItemAdded, _bindingList.Count - 1 /* newIndex*/, -1 /* oldIndex*/);
                        }
                    }
                    break; 

                case CollectionChangeAction.Refresh: 
                    foreach (TViewElement entity in _bindingList) 
                    {
                        Debug.Assert(entity is IEntityWithChangeTracker, "entity must be type IEntityWithChangeTracker"); 
                        listener.UnregisterEntityEvents(entity);
                    }

                    _bindingList.Clear(); 

                    foreach (TViewElement entity in _entityCollection) 
                    { 
                        _bindingList.Add(entity);
 
                        Debug.Assert(entity is IEntityWithChangeTracker, "entity must be type IEntityWithChangeTracker");
                        listener.RegisterEntityEvents(entity);
                    }
 
                    changeArgs = new ListChangedEventArgs(ListChangedType.Reset, -1 /*newIndex*/, -1/*oldIndex*/);
                    break; 
            } 

            return changeArgs; 
        }

        #endregion
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
//---------------------------------------------------------------------- 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// 
// @owner       jhutson
// @backupOwner [....] 
//--------------------------------------------------------------------- 
using System;
using System.Collections.Generic; 
using System.ComponentModel;
using System.Data.Objects.DataClasses;
using System.Diagnostics;
 
namespace System.Data.Objects
{ 
    ///  
    /// Manages a binding list constructed from an EntityCollection.
    ///  
    /// 
    /// Type of the elements in the binding list.
    /// 
    ///  
    /// Type of element in the underlying EntityCollection.
    ///  
    ///  
    /// The binding list is initialized from the EntityCollection,
    /// and is synchronized with changes made to the EntityCollection membership. 
    /// This class always allows additions and removals from the binding list.
    /// 
    internal sealed class ObjectViewEntityCollectionData : IObjectViewData
        where TItemElement : class, IEntityWithRelationships 
        where TViewElement : TItemElement
    { 
        private List _bindingList; 

        private EntityCollection _entityCollection; 

        private readonly bool _canEditItems;

        ///  
        /// True if item that was added to binding list but not underlying entity collection
        /// is now being committed to the collection. 
        /// Otherwise false. 
        /// Used by CommitItemAt and OnCollectionChanged methods to coordinate addition
        /// of new item to underlying entity collection. 
        /// 
        private bool _itemCommitPending;

        ///  
        /// Construct a new instance of the ObjectViewEntityCollectionData class using the supplied entityCollection.
        ///  
        ///  
        /// EntityCollection used to populate the binding list.
        ///  
        internal ObjectViewEntityCollectionData(EntityCollection entityCollection)
        {
            _entityCollection = entityCollection;
 
            _canEditItems = typeof(IEntityWithChangeTracker).IsAssignableFrom(typeof(TViewElement));
 
            _bindingList = new List(entityCollection.Count); 
            foreach (TViewElement entity in entityCollection)
            { 
                _bindingList.Add(entity);
            }
        }
 
        #region IObjectViewData Members
 
        public IList List 
        {
            get { return _bindingList; } 
        }

        public bool AllowNew
        { 
            get { return !_entityCollection.IsReadOnly; }
        } 
 
        public bool AllowEdit
        { 
            get { return _canEditItems; }
        }

        public bool AllowRemove 
        {
            get { return !_entityCollection.IsReadOnly; } 
        } 

        public bool FiresEventOnAdd 
        {
            get { return true; }
        }
 
        public bool FiresEventOnRemove
        { 
            get { return true; } 
        }
 
        public bool FiresEventOnClear
        {
            get { return true; }
        } 

        public void EnsureCanAddNew() 
        { 
            // nop
        } 

        public int Add(TViewElement item, bool isAddNew)
        {
            if (isAddNew) 
            {
                // Item is added to bindingList, but pending addition to entity collection. 
                _bindingList.Add(item); 
            }
            else 
            {
                _entityCollection.Add(item);
                // OnCollectionChanged will be fired, where the binding list will be updated.
            } 

            return _bindingList.Count - 1; 
        } 

        public void CommitItemAt(int index) 
        {
            TViewElement item = _bindingList[index];

            try 
            {
                _itemCommitPending = true; 
 
                _entityCollection.Add(item);
                // OnCollectionChanged will be fired, where the binding list will be updated. 
            }
            finally
            {
                _itemCommitPending = false; 
            }
 
        } 

        public void Clear() 
        {
            if (0 < _bindingList.Count)
            {
                List _deletionList = new List(); 

                foreach (object item in _bindingList) 
                { 
                    _deletionList.Add(item as IEntityWithRelationships);
                } 

                _entityCollection.BulkDeleteAll(_deletionList);
                // EntityCollection will fire change event which this instance will use to clean up the binding list.
            } 
        }
 
        public bool Remove(TViewElement item, bool isCancelNew) 
        {
            bool removed; 

            if (isCancelNew)
            {
                // Item was previously added to binding list, but not entity collection. 
                removed = _bindingList.Remove(item);
            } 
            else 
            {
                removed = _entityCollection.Remove(item); 
                // OnCollectionChanged will be fired, where the binding list will be updated.
            }

            return removed; 
        }
 
        public ListChangedEventArgs OnCollectionChanged(object sender, CollectionChangeEventArgs e, ObjectViewListener listener) 
        {
            ListChangedEventArgs changeArgs = null; 

            switch (e.Action)
            {
                case CollectionChangeAction.Remove: 
                    // An Entity is being removed from entity collection, remove it from list.
                    if (e.Element is TViewElement) 
                    { 
                        TViewElement removedItem = (TViewElement)e.Element;
 
                        int oldIndex = _bindingList.IndexOf(removedItem);
                        if (oldIndex != -1)
                        {
                            _bindingList.Remove(removedItem); 

                            // Unhook from events of removed entity. 
                            listener.UnregisterEntityEvents(removedItem); 

                            changeArgs = new ListChangedEventArgs(ListChangedType.ItemDeleted, oldIndex /* newIndex*/, -1 /* oldIndex*/); 
                        }
                    }
                    break;
 
                case CollectionChangeAction.Add:
                    // Add the entity to our list. 
                    if (e.Element is TViewElement) 
                    {
                        // Do not process Add events that fire as a result of committing an item to the entity collection. 
                        if (!_itemCommitPending)
                        {
                            TViewElement addedItem = (TViewElement)e.Element;
 
                            _bindingList.Add(addedItem);
 
                            // Register to its events. 
                            listener.RegisterEntityEvents(addedItem);
 
                            changeArgs = new ListChangedEventArgs(ListChangedType.ItemAdded, _bindingList.Count - 1 /* newIndex*/, -1 /* oldIndex*/);
                        }
                    }
                    break; 

                case CollectionChangeAction.Refresh: 
                    foreach (TViewElement entity in _bindingList) 
                    {
                        Debug.Assert(entity is IEntityWithChangeTracker, "entity must be type IEntityWithChangeTracker"); 
                        listener.UnregisterEntityEvents(entity);
                    }

                    _bindingList.Clear(); 

                    foreach (TViewElement entity in _entityCollection) 
                    { 
                        _bindingList.Add(entity);
 
                        Debug.Assert(entity is IEntityWithChangeTracker, "entity must be type IEntityWithChangeTracker");
                        listener.RegisterEntityEvents(entity);
                    }
 
                    changeArgs = new ListChangedEventArgs(ListChangedType.Reset, -1 /*newIndex*/, -1/*oldIndex*/);
                    break; 
            } 

            return changeArgs; 
        }

        #endregion
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.

Link Menu

Network programming in C#, Network Programming in VB.NET, Network Programming in .NET
This book is available now!
Buy at Amazon US or
Buy at Amazon UK