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//---------------------------------------------------------------------
// <copyright file="BindingObserver.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
// <summary>
// BindingObserver class
// </summary>
//
//---------------------------------------------------------------------
namespace System.Data.Services.Client
{
#region Namespaces
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Diagnostics;
using System.Linq;
using System.Reflection;
#endregion
/// <summary>The BindingObserver class</summary>
internal sealed class BindingObserver
{
#region Fields
/// <summary>
/// The BindingGraph maps objects tracked by the DataServiceContext to vertices in a
/// graph used to manage the information needed for data binding. The objects tracked
/// by the BindingGraph are entities, complex types and DataServiceCollections.
/// </summary>
private BindingGraph bindingGraph;
#endregion
#region Constructor
/// <summary>Constructor</summary>
/// <param name="context">The DataServiceContext associated with the BindingObserver.</param>
/// <param name="entityChanged">EntityChanged delegate.</param>
/// <param name="collectionChanged">EntityCollectionChanged delegate.</param>
internal BindingObserver(DataServiceContext context, Func<EntityChangedParams, bool> entityChanged, Func<EntityCollectionChangedParams, bool> collectionChanged)
{
Debug.Assert(context != null, "Must have been validated during DataServiceCollection construction.");
this.Context = context;
this.Context.ChangesSaved += this.OnChangesSaved;
this.EntityChanged = entityChanged;
this.CollectionChanged = collectionChanged;
this.bindingGraph = new BindingGraph(this);
}
#endregion
#region Properties
/// <summary>The DataServiceContext associated with the BindingObserver.</summary>
internal DataServiceContext Context
{
get;
private set;
}
/// <summary>The behavior of add operations should be Attach or Add on the context.</summary>
internal bool AttachBehavior
{
get;
set;
}
/// <summary>The behavior of remove operations should be Detach on the context.</summary>
internal bool DetachBehavior
{
get;
set;
}
/// <summary>
/// Callback invoked when a property of an entity object tracked by the BindingObserver has changed.
/// </summary>
/// <remarks>
/// Entity objects tracked by the BindingObserver implement INotifyPropertyChanged. Events of this type
/// flow throw the EntityChangedParams. If this callback is not implemented by user code, or the user code
/// implementation returns false, the BindingObserver executes a default implementation for the callback.
/// </remarks>
internal Func<EntityChangedParams, bool> EntityChanged
{
get;
private set;
}
/// <summary>
/// Callback invoked when an DataServiceCollection tracked by the BindingObserver has changed.
/// </summary>
/// <remarks>
/// DataServiceCollection objects tracked by the BindingObserver implement INotifyCollectionChanged.
/// Events of this type flow throw the EntityCollectionChanged callback. If this callback is not
/// implemented by user code, or the user code implementation returns false, the BindingObserver executes
/// a default implementation for the callback.
/// </remarks>
internal Func<EntityCollectionChangedParams, bool> CollectionChanged
{
get;
private set;
}
#endregion
#region Methods
/// <summary>Start tracking the specified DataServiceCollection.</summary>
/// <typeparam name="T">An entity type.</typeparam>
/// <param name="collection">An DataServiceCollection.</param>
/// <param name="collectionEntitySet">The entity set of the elements in <paramref name="collection"/>.</param>
internal void StartTracking<T>(DataServiceCollection<T> collection, string collectionEntitySet)
{
Debug.Assert(collection != null, "Only constructed collections are tracked.");
// Verify that T corresponds to an entity type.
if (!BindingEntityInfo.IsEntityType(typeof(T)))
{
throw new ArgumentException(Strings.DataBinding_DataServiceCollectionArgumentMustHaveEntityType(typeof(T)));
}
try
{
this.AttachBehavior = true;
// Recursively traverse the entire object graph under the root collection.
this.bindingGraph.AddCollection(null, null, collection, collectionEntitySet);
}
finally
{
this.AttachBehavior = false;
}
}
/// <summary>Stop tracking the root DataServiceCollection associated with the observer.</summary>
internal void StopTracking()
{
this.bindingGraph.Reset();
this.Context.ChangesSaved -= this.OnChangesSaved;
}
#if ASTORIA_LIGHT
internal bool LookupParent<T>(DataServiceCollection<T> collection, out object parentEntity, out string parentProperty)
{
string sourceEntitySet;
string targetEntitySet;
this.bindingGraph.GetEntityCollectionInfo(collection, out parentEntity, out parentProperty, out sourceEntitySet, out targetEntitySet);
return parentEntity != null;
}
#endif
/// <summary>Handle changes to tracked entity.</summary>
/// <param name="source">The entity that raised the event.</param>
/// <param name="eventArgs">Information about the event such as changed property name.</param>
[System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.NoInlining | System.Runtime.CompilerServices.MethodImplOptions.NoOptimization)]
internal void OnPropertyChanged(object source, PropertyChangedEventArgs eventArgs)
{
Util.CheckArgumentNull(source, "source");
Util.CheckArgumentNull(eventArgs, "eventArgs");
#if DEBUG
Debug.Assert(this.bindingGraph.IsTracking(source), "Entity must be part of the graph if it has the event notification registered.");
#endif
string sourceProperty = eventArgs.PropertyName;
// When sourceProperty is null, it is assumed that all properties for the object changed
// As a result, we should be performing an UpdateObject operation on the context.
if (String.IsNullOrEmpty(sourceProperty))
{
this.HandleUpdateEntity(
source,
null,
null);
}
else
{
BindingEntityInfo.BindingPropertyInfo bpi;
// Get the new value for the changed property.
object sourcePropertyValue = BindingEntityInfo.GetPropertyValue(source, sourceProperty, out bpi);
// Check if it is an interesting property e.g. collection, entity reference or complex type.
if (bpi != null)
{
// Disconnect the edge between source and original source property value.
this.bindingGraph.RemoveRelation(source, sourceProperty);
switch (bpi.PropertyKind)
{
case BindingPropertyKind.BindingPropertyKindCollection:
// If collection is already being tracked by the graph we can not have > 1 links to it.
if (sourcePropertyValue != null)
{
// Make sure that there is no observer on the input collection property.
try
{
typeof(BindingUtils)
.GetMethod("VerifyObserverNotPresent", BindingFlags.NonPublic | BindingFlags.Static)
.MakeGenericMethod(bpi.PropertyInfo.CollectionType)
.Invoke(null, new object[] { sourcePropertyValue, sourceProperty, source.GetType() });
}
catch (TargetInvocationException tie)
{
throw tie.InnerException;
}
try
{
this.AttachBehavior = true;
this.bindingGraph.AddCollection(
source,
sourceProperty,
sourcePropertyValue,
null);
}
finally
{
this.AttachBehavior = false;
}
}
break;
case BindingPropertyKind.BindingPropertyKindEntity:
// Add the newly added entity to the graph, or update entity reference.
this.bindingGraph.AddEntity(
source,
sourceProperty,
sourcePropertyValue,
null,
source);
break;
default:
Debug.Assert(bpi.PropertyKind == BindingPropertyKind.BindingPropertyKindComplex, "Must be complex type if PropertyKind is not entity or collection.");
// Attach the newly assigned complex type object and it's child complex typed objects.
if (sourcePropertyValue != null)
{
this.bindingGraph.AddComplexProperty(
source,
sourceProperty,
sourcePropertyValue);
}
this.HandleUpdateEntity(
source,
sourceProperty,
sourcePropertyValue);
break;
}
}
else
{
// For non-interesting properties i.e. value types or regular collection properties we simply call UpdateObject on the context.
// Note that this code also handles primitive properties of complex typed objects.
this.HandleUpdateEntity(
source,
sourceProperty,
sourcePropertyValue);
}
}
}
/// <summary>Handle changes to tracked DataServiceCollection.</summary>
/// <param name="collection">The DataServiceCollection that raised the event.</param>
/// <param name="eventArgs">Information about the event such as added/removed entities, operation.</param>
internal void OnCollectionChanged(object collection, NotifyCollectionChangedEventArgs eventArgs)
{
Util.CheckArgumentNull(collection, "collection");
Util.CheckArgumentNull(eventArgs, "eventArgs");
Debug.Assert(BindingEntityInfo.IsDataServiceCollection(collection.GetType()), "We only register this event for DataServiceCollections.");
#if DEBUG
Debug.Assert(this.bindingGraph.IsTracking(collection), "Collection must be part of the graph if it has the event notification registered.");
#endif
object source;
string sourceProperty;
string sourceEntitySet;
string targetEntitySet;
this.bindingGraph.GetEntityCollectionInfo(
collection,
out source,
out sourceProperty,
out sourceEntitySet,
out targetEntitySet);
switch (eventArgs.Action)
{
case NotifyCollectionChangedAction.Add:
// This event is raised by ObservableCollection.InsertItem.
this.OnAddToCollection(
eventArgs,
source,
sourceProperty,
targetEntitySet,
collection);
break;
case NotifyCollectionChangedAction.Remove:
// This event is raised by ObservableCollection.RemoveItem.
this.OnDeleteFromCollection(
eventArgs,
source,
sourceProperty,
collection);
break;
case NotifyCollectionChangedAction.Replace:
// This event is raised by ObservableCollection.SetItem.
this.OnDeleteFromCollection(
eventArgs,
source,
sourceProperty,
collection);
this.OnAddToCollection(
eventArgs,
source,
sourceProperty,
targetEntitySet,
collection);
break;
case NotifyCollectionChangedAction.Reset:
// This event is raised by ObservableCollection.Clear.
if (this.DetachBehavior)
{
// Detach behavior requires going through each item and detaching it from context.
this.RemoveWithDetachCollection(collection);
}
else
{
// Non-detach behavior requires only removing vertices of collection from graph.
this.bindingGraph.RemoveCollection(collection);
}
break;
#if !ASTORIA_LIGHT
case NotifyCollectionChangedAction.Move:
// Do Nothing. Added for completeness.
break;
#endif
default:
throw new InvalidOperationException(Strings.DataBinding_CollectionChangedUnknownAction(eventArgs.Action));
}
}
/// <summary>Handle Adds to a tracked DataServiceCollection. Perform operations on context to reflect the changes.</summary>
/// <param name="source">The source object that reference the target object through a navigation property.</param>
/// <param name="sourceProperty">The navigation property in the source object that reference the target object.</param>
/// <param name="sourceEntitySet">The entity set of the source object.</param>
/// <param name="collection">The collection containing the target object.</param>
/// <param name="target">The target entity to attach.</param>
/// <param name="targetEntitySet">The entity set name of the target object.</param>
internal void HandleAddEntity(
object source,
string sourceProperty,
string sourceEntitySet,
ICollection collection,
object target,
string targetEntitySet)
{
if (this.Context.ApplyingChanges)
{
return;
}
Debug.Assert(
(source == null && sourceProperty == null) || (source != null && !String.IsNullOrEmpty(sourceProperty)),
"source and sourceProperty should either both be present or both be absent.");
Debug.Assert(target != null, "target must be provided by the caller.");
Debug.Assert(BindingEntityInfo.IsEntityType(target.GetType()), "target must be an entity type.");
// Do not handle add for already detached and deleted entities.
if (source != null && this.IsDetachedOrDeletedFromContext(source))
{
return;
}
// Do we need an operation on context to handle the Add operation.
EntityDescriptor targetDescriptor = this.Context.GetEntityDescriptor(target);
// Following are the conditions where context operation is required:
// 1. Not a call to Load or constructions i.e. we have Add behavior and not Attach behavior
// 2. Target entity is not being tracked
// 3. Target is being tracked but there is no link between the source and target entity and target is in non-deleted state
bool contextOperationRequired = !this.AttachBehavior &&
(targetDescriptor == null ||
(source != null && !this.IsContextTrackingLink(source, sourceProperty, target) && targetDescriptor.State != EntityStates.Deleted));
if (contextOperationRequired)
{
// First give the user code a chance to handle Add operation.
if (this.CollectionChanged != null)
{
EntityCollectionChangedParams args = new EntityCollectionChangedParams(
this.Context,
source,
sourceProperty,
sourceEntitySet,
collection,
target,
targetEntitySet,
NotifyCollectionChangedAction.Add);
if (this.CollectionChanged(args))
{
return;
}
}
}
// The user callback code could detach the source.
if (source != null && this.IsDetachedOrDeletedFromContext(source))
{
throw new InvalidOperationException(Strings.DataBinding_BindingOperation_DetachedSource);
}
// Default implementation.
targetDescriptor = this.Context.GetEntityDescriptor(target);
if (source != null)
{
if (this.AttachBehavior)
{
// If the target entity is not being currently tracked, we attach both the
// entity and the link between source and target entity.
if (targetDescriptor == null)
{
BindingUtils.ValidateEntitySetName(targetEntitySet, target);
this.Context.AttachTo(targetEntitySet, target);
this.Context.AttachLink(source, sourceProperty, target);
}
else
if (targetDescriptor.State != EntityStates.Deleted && !this.IsContextTrackingLink(source, sourceProperty, target))
{
// If the target is already being tracked, then we attach the link if it
// does not already exist between the source and target entities and the
// target entity is not already in Deleted state.
this.Context.AttachLink(source, sourceProperty, target);
}
}
else
{
// The target will be added and link from source to target will get established in the code
// below. Note that if there is already target present then we just try to establish the link
// however, if the link is also already established then we don't do anything.
if (targetDescriptor == null)
{
// If the entity is not tracked, that means the entity needs to
// be added to the context. We need to call AddRelatedObject,
// which adds via the parent (for e.g. POST Customers(0)/Orders).
this.Context.AddRelatedObject(source, sourceProperty, target);
}
else
if (targetDescriptor.State != EntityStates.Deleted && !this.IsContextTrackingLink(source, sourceProperty, target))
{
// If the entity is already tracked, then we just add the link.
// However, we would not do it if the target entity is already
// in a Deleted state.
this.Context.AddLink(source, sourceProperty, target);
}
}
}
else
if (targetDescriptor == null)
{
// The source is null when the DataServiceCollection is the root collection.
BindingUtils.ValidateEntitySetName(targetEntitySet, target);
if (this.AttachBehavior)
{
// Attach the target entity.
this.Context.AttachTo(targetEntitySet, target);
}
else
{
// Add the target entity.
this.Context.AddObject(targetEntitySet, target);
}
}
}
/// <summary>Handle Deletes from a tracked DataServiceCollection. Perform operations on context to reflect the changes.</summary>
/// <param name="source">The source object that reference the target object through a navigation property.</param>
/// <param name="sourceProperty">The navigation property in the source object that reference the target object.</param>
/// <param name="sourceEntitySet">The entity set of the source object.</param>
/// <param name="collection">The collection containing the target object.</param>
/// <param name="target">The target entity.</param>
/// <param name="targetEntitySet">The entity set name of the target object.</param>
internal void HandleDeleteEntity(
object source,
string sourceProperty,
string sourceEntitySet,
ICollection collection,
object target,
string targetEntitySet)
{
if (this.Context.ApplyingChanges)
{
return;
}
Debug.Assert(
(source == null && sourceProperty == null) || (source != null && !String.IsNullOrEmpty(sourceProperty)),
"source and sourceProperty should either both be present or both be absent.");
Debug.Assert(target != null, "target must be provided by the caller.");
Debug.Assert(BindingEntityInfo.IsEntityType(target.GetType()), "target must be an entity type.");
Debug.Assert(!this.AttachBehavior, "AttachBehavior is only allowed during Construction and Load when this method should never be entered.");
// Do not handle delete for already detached and deleted entities.
if (source != null && this.IsDetachedOrDeletedFromContext(source))
{
return;
}
// Do we need an operation on context to handle the Delete operation.
// Detach behavior is special because it is only applicable in Clear
// cases, where we don't callback users for detach nofications.
bool contextOperationRequired = this.IsContextTrackingEntity(target) && !this.DetachBehavior;
if (contextOperationRequired)
{
// First give the user code a chance to handle Delete operation.
if (this.CollectionChanged != null)
{
EntityCollectionChangedParams args = new EntityCollectionChangedParams(
this.Context,
source,
sourceProperty,
sourceEntitySet,
collection,
target,
targetEntitySet,
NotifyCollectionChangedAction.Remove);
if (this.CollectionChanged(args))
{
return;
}
}
}
// The user callback code could detach the source.
if (source != null && !this.IsContextTrackingEntity(source))
{
throw new InvalidOperationException(Strings.DataBinding_BindingOperation_DetachedSource);
}
// Default implementation.
// Remove the entity from the context if it is currently being tracked.
if (this.IsContextTrackingEntity(target))
{
if (this.DetachBehavior)
{
this.Context.Detach(target);
}
else
{
this.Context.DeleteObject(target);
}
}
}
/// <summary>Handle changes to navigation properties of a tracked entity. Perform operations on context to reflect the changes.</summary>
/// <param name="source">The source object that reference the target object through a navigation property.</param>
/// <param name="sourceProperty">The navigation property in the source object that reference the target object.</param>
/// <param name="sourceEntitySet">The entity set of the source object.</param>
/// <param name="target">The target entity.</param>
/// <param name="targetEntitySet">The entity set name of the target object.</param>
internal void HandleUpdateEntityReference(
object source,
string sourceProperty,
string sourceEntitySet,
object target,
string targetEntitySet)
{
if (this.Context.ApplyingChanges)
{
return;
}
Debug.Assert(source != null, "source can not be null for update operations.");
Debug.Assert(BindingEntityInfo.IsEntityType(source.GetType()), "source must be an entity with keys.");
Debug.Assert(!String.IsNullOrEmpty(sourceProperty), "sourceProperty must be a non-empty string for update operations.");
Debug.Assert(!String.IsNullOrEmpty(sourceEntitySet), "sourceEntitySet must be non-empty string for update operation.");
// Do not handle update for detached and deleted entities.
if (this.IsDetachedOrDeletedFromContext(source))
{
return;
}
// Do we need an operation on context to handle the Update operation.
EntityDescriptor targetDescriptor = target != null ? this.Context.GetEntityDescriptor(target) : null;
// Following are the conditions where context operation is required:
// 1. Not a call to Load or constructions i.e. we have Add behavior and not Attach behavior
// 2. Target entity is not being tracked
// 3. Target is being tracked but there is no link between the source and target entity
bool contextOperationRequired = !this.AttachBehavior &&
(targetDescriptor == null ||
!this.IsContextTrackingLink(source, sourceProperty, target));
if (contextOperationRequired)
{
// First give the user code a chance to handle Update link operation.
if (this.EntityChanged != null)
{
EntityChangedParams args = new EntityChangedParams(
this.Context,
source,
sourceProperty,
target,
sourceEntitySet,
targetEntitySet);
if (this.EntityChanged(args))
{
return;
}
}
}
// The user callback code could detach the source.
if (this.IsDetachedOrDeletedFromContext(source))
{
throw new InvalidOperationException(Strings.DataBinding_BindingOperation_DetachedSource);
}
// Default implementation.
targetDescriptor = target != null ? this.Context.GetEntityDescriptor(target) : null;
if (target != null)
{
if (targetDescriptor == null)
{
// If the entity set name is not known, then we must throw since we need to know the
// entity set in order to add/attach the referenced object to it's entity set.
BindingUtils.ValidateEntitySetName(targetEntitySet, target);
if (this.AttachBehavior)
{
this.Context.AttachTo(targetEntitySet, target);
}
else
{
this.Context.AddObject(targetEntitySet, target);
}
targetDescriptor = this.Context.GetEntityDescriptor(target);
}
// if the entity is already tracked, then just set/attach the link. However, do
// not try to attach the link if the target is in Deleted state.
if (!this.IsContextTrackingLink(source, sourceProperty, target))
{
if (this.AttachBehavior)
{
if (targetDescriptor.State != EntityStates.Deleted)
{
this.Context.AttachLink(source, sourceProperty, target);
}
}
else
{
this.Context.SetLink(source, sourceProperty, target);
}
}
}
else
{
Debug.Assert(!this.AttachBehavior, "During attach operations we must never perform operations for null values.");
// The target could be null in which case we just need to set the link to null.
this.Context.SetLink(source, sourceProperty, null);
}
}
/// <summary>Determine if the DataServiceContext is tracking the specified entity.</summary>
/// <param name="entity">An entity object.</param>
/// <returns>true if the entity is tracked; otherwise false.</returns>
internal bool IsContextTrackingEntity(object entity)
{
Debug.Assert(entity != null, "entity must be provided when checking for context tracking.");
return this.Context.GetEntityDescriptor(entity) != default(EntityDescriptor);
}
/// <summary>
/// Handle changes to an entity object tracked by the BindingObserver
/// </summary>
/// <param name="entity">The entity object that has changed.</param>
/// <param name="propertyName">The property of the target entity object that has changed.</param>
/// <param name="propertyValue">The value of the changed property of the target object.</param>
private void HandleUpdateEntity(object entity, string propertyName, object propertyValue)
{
Debug.Assert(!this.AttachBehavior || this.Context.ApplyingChanges, "Entity updates must not happen during Attach or construction phases, deserialization case is the exception.");
if (this.Context.ApplyingChanges)
{
return;
}
// For complex types, we will perform notification and update on the closest ancestor entity using the farthest ancestor complex property.
if (!BindingEntityInfo.IsEntityType(entity.GetType()))
{
this.bindingGraph.GetAncestorEntityForComplexProperty(ref entity, ref propertyName, ref propertyValue);
}
Debug.Assert(entity != null, "entity must be provided for update operations.");
Debug.Assert(BindingEntityInfo.IsEntityType(entity.GetType()), "entity must be an entity with keys.");
Debug.Assert(!String.IsNullOrEmpty(propertyName) || propertyValue == null, "When propertyName is null no propertyValue should be provided.");
// Do not handle update for detached and deleted entities.
if (this.IsDetachedOrDeletedFromContext(entity))
{
return;
}
// First give the user code a chance to handle Update operation.
if (this.EntityChanged != null)
{
EntityChangedParams args = new EntityChangedParams(
this.Context,
entity,
propertyName,
propertyValue,
null,
null);
if (this.EntityChanged(args))
{
return;
}
}
// Default implementation.
// The user callback code could detach the entity.
if (this.IsContextTrackingEntity(entity))
{
// Let UpdateObject check the state of the entity.
this.Context.UpdateObject(entity);
}
}
/// <summary>Processes the INotifyCollectionChanged.Add event.</summary>
/// <param name="eventArgs">Event information such as added items.</param>
/// <param name="source">Parent entity to which collection belongs.</param>
/// <param name="sourceProperty">Parent entity property referring to collection.</param>
/// <param name="targetEntitySet">Entity set of the collection.</param>
/// <param name="collection">Collection that changed.</param>
private void OnAddToCollection(
NotifyCollectionChangedEventArgs eventArgs,
object source,
String sourceProperty,
String targetEntitySet,
object collection)
{
Debug.Assert(collection != null, "Must have a valid collection to which entities are added.");
if (eventArgs.NewItems != null)
{
foreach (object target in eventArgs.NewItems)
{
if (target == null)
{
throw new InvalidOperationException(Strings.DataBinding_BindingOperation_ArrayItemNull("Add"));
}
if (!BindingEntityInfo.IsEntityType(target.GetType()))
{
throw new InvalidOperationException(Strings.DataBinding_BindingOperation_ArrayItemNotEntity("Add"));
}
// Start tracking the target entity and synchronize the context with the Add operation.
this.bindingGraph.AddEntity(
source,
sourceProperty,
target,
targetEntitySet,
collection);
}
}
}
/// <summary>Processes the INotifyCollectionChanged.Remove event.</summary>
/// <param name="eventArgs">Event information such as deleted items.</param>
/// <param name="source">Parent entity to which collection belongs.</param>
/// <param name="sourceProperty">Parent entity property referring to collection.</param>
/// <param name="collection">Collection that changed.</param>
private void OnDeleteFromCollection(
NotifyCollectionChangedEventArgs eventArgs,
object source,
String sourceProperty,
object collection)
{
Debug.Assert(collection != null, "Must have a valid collection from which entities are removed.");
Debug.Assert(
(source == null && sourceProperty == null) || (source != null && !String.IsNullOrEmpty(sourceProperty)),
"source and sourceProperty must both be null or both be non-null.");
if (eventArgs.OldItems != null)
{
this.DeepRemoveCollection(
eventArgs.OldItems,
source ?? collection,
sourceProperty,
this.ValidateCollectionItem);
}
}
/// <summary>Removes a collection from the binding graph and detaches each item.</summary>
/// <param name="collection">Collection whose elements are to be removed and detached.</param>
private void RemoveWithDetachCollection(object collection)
{
Debug.Assert(this.DetachBehavior, "Must be detaching each item in collection.");
object source = null;
string sourceProperty = null;
string sourceEntitySet = null;
string targetEntitySet = null;
this.bindingGraph.GetEntityCollectionInfo(
collection,
out source,
out sourceProperty,
out sourceEntitySet,
out targetEntitySet);
this.DeepRemoveCollection(
this.bindingGraph.GetCollectionItems(collection),
source ?? collection,
sourceProperty,
null);
}
/// <summary>Performs a Deep removal of all entities in a collection.</summary>
/// <param name="collection">Collection whose items are removed from binding graph.</param>
/// <param name="source">Parent item whose property refer to the <paramref name="collection"/> being cleared.</param>
/// <param name="sourceProperty">Property of the <paramref name="source"/> that refers to <paramref name="collection"/>.</param>
/// <param name="itemValidator">Validation method if any that checks the individual item in <paramref name="collection"/> for validity.</param>
private void DeepRemoveCollection(IEnumerable collection, object source, string sourceProperty, Action<object> itemValidator)
{
foreach (object target in collection)
{
if (itemValidator != null)
{
itemValidator(target);
}
// Accumulate the list of entities to untrack, this includes deep added entities under target.
List<UnTrackingInfo> untrackingInfo = new List<UnTrackingInfo>();
this.CollectUnTrackingInfo(
target,
source,
sourceProperty,
untrackingInfo);
// Stop tracking the collection of entities found by CollectUnTrackingInfo from bottom up in object graph.
foreach (UnTrackingInfo info in untrackingInfo)
{
this.bindingGraph.Remove(
info.Entity,
info.Parent,
info.ParentProperty);
}
}
this.bindingGraph.RemoveUnreachableVertices();
}
/// <summary>Handle the DataServiceContext.SaveChanges operation.</summary>
/// <param name="sender">DataServiceContext for the observer.</param>
/// <param name="eventArgs">Information about SaveChanges operation results.</param>
private void OnChangesSaved(object sender, SaveChangesEventArgs eventArgs)
{
// Does the response status code have to be checked? SaveChanges throws on failure.
// DataServiceResponse response = eventArgs.Response;
this.bindingGraph.RemoveNonTrackedEntities();
}
/// <summary>Collects a list of entities that observer is supposed to stop tracking</summary>
/// <param name="currentEntity">Entity being delete along with it's children</param>
/// <param name="parentEntity">Parent of the <paramref name="currentEntity"/></param>
/// <param name="parentProperty">Property by which <paramref name="parentEntity"/> refers to <paramref name="currentEntity"/></param>
/// <param name="entitiesToUnTrack">List in which entities to be untracked are collected</param>
private void CollectUnTrackingInfo(
object currentEntity,
object parentEntity,
string parentProperty,
IList<UnTrackingInfo> entitiesToUnTrack)
{
// We need to delete the child objects first before we delete the parent
foreach (var ed in this.Context
.Entities
.Where(x => x.ParentEntity == currentEntity && x.State == EntityStates.Added))
{
this.CollectUnTrackingInfo(
ed.Entity,
ed.ParentEntity,
ed.ParentPropertyForInsert,
entitiesToUnTrack);
}
entitiesToUnTrack.Add(new UnTrackingInfo
{
Entity = currentEntity,
Parent = parentEntity,
ParentProperty = parentProperty
});
}
/// <summary>Determine if the DataServiceContext is tracking link between <paramref name="source"/> and <paramref name="target"/>.</summary>
/// <param name="source">The source object side of the link.</param>
/// <param name="sourceProperty">A property in the source side of the link that references the target.</param>
/// <param name="target">The target object side of the link.</param>
/// <returns>True if the link is tracked; otherwise false.</returns>
private bool IsContextTrackingLink(object source, string sourceProperty, object target)
{
Debug.Assert(source != null, "source entity must be provided.");
Debug.Assert(BindingEntityInfo.IsEntityType(source.GetType()), "source must be an entity with keys.");
Debug.Assert(!String.IsNullOrEmpty(sourceProperty), "sourceProperty must be provided.");
Debug.Assert(target != null, "target entity must be provided.");
Debug.Assert(BindingEntityInfo.IsEntityType(target.GetType()), "target must be an entity with keys.");
return this.Context.GetLinkDescriptor(source, sourceProperty, target) != default(LinkDescriptor);
}
/// <summary>Checks whether the given entity is in detached or deleted state.</summary>
/// <param name="entity">Entity being checked.</param>
/// <returns>true if the entity is detached or deleted, otherwise returns false.</returns>
private bool IsDetachedOrDeletedFromContext(object entity)
{
Debug.Assert(entity != null, "entity must be provided.");
Debug.Assert(BindingEntityInfo.IsEntityType(entity.GetType()), "entity must be an entity with keys.");
EntityDescriptor descriptor = this.Context.GetEntityDescriptor(entity);
return descriptor == null || descriptor.State == EntityStates.Deleted;
}
/// <summary>Entity validator that checks if the <paramref name="target"/> is of entity type.</summary>
/// <param name="target">Entity being validated.</param>
private void ValidateCollectionItem(object target)
{
if (target == null)
{
throw new InvalidOperationException(Strings.DataBinding_BindingOperation_ArrayItemNull("Remove"));
}
if (!BindingEntityInfo.IsEntityType(target.GetType()))
{
throw new InvalidOperationException(Strings.DataBinding_BindingOperation_ArrayItemNotEntity("Remove"));
}
}
#endregion
/// <summary>Information regarding each entity to be untracked</summary>
private class UnTrackingInfo
{
/// <summary>Entity to untrack</summary>
public object Entity
{
get;
set;
}
/// <summary>Parent object of <see cref="Entity"/></summary>
public object Parent
{
get;
set;
}
/// <summary>Parent object property referring to <see cref="Entity"/></summary>
public string ParentProperty
{
get;
set;
}
}
}
}
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