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//---------------------------------------------------------------------
// <copyright file="EntityReference.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//
// @owner Microsoft
// @backupOwner Microsoft
//---------------------------------------------------------------------
namespace System.Data.Objects.DataClasses
{
using System.Collections.Generic;
using System.Data;
using System.Data.Common.Utils;
using System.Data.Metadata.Edm;
using System.Data.Objects.Internal;
using System.Diagnostics;
using System.Linq;
using System.Runtime.Serialization;
/// <summary>
/// Models a relationship end with multiplicity 1.
/// </summary>
[DataContract]
[Serializable]
public abstract class EntityReference : RelatedEnd
{
// ------
// Fields
// ------
// The following fields are serialized. Adding or removing a serialized field is considered
// a breaking change. This includes changing the field type or field name of existing
// serialized fields. If you need to make this kind of change, it may be possible, but it
// will require some custom serialization/deserialization code.
// The following field is valid only for detached EntityReferences, see EntityKey property for more details.
private EntityKey _detachedEntityKey = null;
// The following field is used to cache the FK value to the principal for FK relationships.
// It is okay to not serialize this field because it is only used when the entity is tracked.
// For a detached entity it can always be null and cause no problems.
[NonSerialized]
private EntityKey _cachedForeignKey;
// ------------
// Constructors
// ------------
/// <summary>
/// The default constructor is required for some serialization scenarios. It should not be used to
/// create new EntityReferences. Use the GetRelatedReference or GetRelatedEnd methods on the RelationshipManager
/// class instead.
/// </summary>
internal EntityReference()
{
}
internal EntityReference(IEntityWrapper wrappedOwner, RelationshipNavigation navigation, IRelationshipFixer relationshipFixer)
: base(wrappedOwner, navigation, relationshipFixer)
{
}
/// <summary>
/// Returns the EntityKey of the target entity associated with this EntityReference.
///
/// Is non-null in the following scenarios:
/// (a) Entities are tracked by a context and an Unchanged or Added client-side relationships exists for this EntityReference's owner with the
/// same RelationshipName and source role. This relationship could have been created explicitly by the user (e.g. by setting
/// the EntityReference.Value, setting this property directly, or by calling EntityCollection.Add) or automatically through span queries.
/// (b) If the EntityKey was non-null before detaching an entity from the context, it will still be non-null after detaching, until any operation
/// occurs that would set it to null, as described below.
/// (c) Entities are detached and the EntityKey is explicitly set to non-null by the user.
/// (d) Entity graph was created using a NoTracking query with full span
///
/// Is null in the following scenarios:
/// (a) Entities are tracked by a context but there is no Unchanged or Added client-side relationship for this EntityReference's owner with the
/// same RelationshipName and source role.
/// (b) Entities are tracked by a context and a relationship exists, but the target entity has a temporary key (i.e. it is Added) or the key
/// is one of the special keys
/// (c) Entities are detached and the relationship was explicitly created by the user.
/// </summary>
[DataMember]
public EntityKey EntityKey
{
// This is the only scenario where it is valid to have a null Owner, so don't check it
get
{
if (this.ObjectContext != null && !UsingNoTracking)
{
Debug.Assert(this.WrappedOwner.Entity != null, "Unexpected null Owner on EntityReference attached to a context");
EntityKey attachedKey = null;
// If this EntityReference contains an entity, look up the key on that object
if (CachedValue.Entity != null)
{
// While processing an attach the owner may have a context while the target does not. This means
// that the target may gave an entity but not yet have an attached entity key.
attachedKey = CachedValue.EntityKey;
if (attachedKey != null && !IsValidEntityKeyType(attachedKey))
{
// don't return temporary or special keys from this property
attachedKey = null;
}
}
else
{
if (IsForeignKey)
{
// For dependent ends, return the value of the cached foreign key if it is not conceptually null
if (IsDependentEndOfReferentialConstraint(false) && _cachedForeignKey != null)
{
if (!ForeignKeyFactory.IsConceptualNullKey(_cachedForeignKey))
{
attachedKey = _cachedForeignKey;
}
}
else
{
// Principal ends or ends that haven't been fixed up yet (i.e during Add/Attach) should use the DetachedEntityKey value
// that contains the last known value that was set
attachedKey = DetachedEntityKey;
}
}
else
{
// There could still be an Added or Unchanged relationship with a stub entry
EntityKey ownerKey = WrappedOwner.EntityKey;
foreach (RelationshipEntry relationshipEntry in this.ObjectContext.ObjectStateManager.FindRelationshipsByKey(ownerKey))
{
// We only care about the relationships that match the AssociationSet and source role for the owner of this EntityReference
if (relationshipEntry.State != EntityState.Deleted &&
relationshipEntry.IsSameAssociationSetAndRole((AssociationSet)RelationshipSet, (AssociationEndMember)this.FromEndProperty, ownerKey))
{
Debug.Assert(attachedKey == null, "Found more than one non-Deleted relationship for the same AssociationSet and source role");
attachedKey = relationshipEntry.RelationshipWrapper.GetOtherEntityKey(ownerKey);
// key should never be temporary or special since it came from a key entry
}
}
}
}
Debug.Assert(attachedKey == null || IsValidEntityKeyType(attachedKey),
"Unexpected temporary or special key");
return attachedKey;
}
else
{
return DetachedEntityKey;
}
}
set
{
SetEntityKey(value, forceFixup: false);
}
}
internal void SetEntityKey(EntityKey value, bool forceFixup)
{
if (value != null && value == EntityKey && (ReferenceValue.Entity != null || (ReferenceValue.Entity == null && !forceFixup)))
{
// "no-op" -- this is not really no-op in the attached case, because at a minimum we have to do a key lookup,
// worst case we have to review all relationships for the owner entity
// However, if we don't do this, we can get into a scenario where we are setting the key to the same thing it's already set to
// and this could have side effects, especially with RI constraints and cascade delete. We don't want to delete something
// and then add it back, if that deleting could have additional unexpected effects. Don't bother doing this check if value is
// null, because EntityKey could be null even if there are Added/Unchanged relationships, if the target entity has a temporary key.
// In that case, we still need to delete that existing relationship, so it's not a no-op
return;
}
if (this.ObjectContext != null && !UsingNoTracking)
{
Debug.Assert(this.WrappedOwner.Entity != null, "Unexpected null Owner on EntityReference attached to a context");
// null is a valid value for the EntityKey, but temporary and special keys are not
// devnote: Can't check this on detached references because this property could be set to a temp key during deserialization,
// if the key hasn't finished deserializing yet.
if (value != null && !IsValidEntityKeyType(value))
{
throw EntityUtil.CannotSetSpecialKeys();
}
if (value == null)
{
if (AttemptToNullFKsOnRefOrKeySetToNull())
{
DetachedEntityKey = null;
}
else
{
ReferenceValue = EntityWrapperFactory.NullWrapper;
}
}
else
{
// Verify that the key has the right EntitySet for this RelationshipSet
EntitySet targetEntitySet = value.GetEntitySet(ObjectContext.MetadataWorkspace);
CheckRelationEntitySet(targetEntitySet);
value.ValidateEntityKey(ObjectContext.MetadataWorkspace, targetEntitySet, true /*isArgumentException */, "value");
ObjectStateManager manager = this.ObjectContext.ObjectStateManager;
// If we already have an entry with this key, we just need to create a relationship with it
bool addNewRelationship = false;
// If we don't already have any matching entries for this key, we'll have to create a new entry
bool addKeyEntry = false;
EntityEntry targetEntry = manager.FindEntityEntry(value);
if (targetEntry != null)
{
// If it's not a key entry, just use the entity to set this reference's Value
if (!targetEntry.IsKeyEntry)
{
// Delegate to the Value property to clear any existing relationship
// and to add the new one. This will fire the appropriate events and
// ensure that the related ends are connected.
// It has to be a TEntity since we already verified that the EntitySet is correct above
this.ReferenceValue = targetEntry.WrappedEntity;
}
else
{
// if the existing entry is a key entry, we just need to
// add a new relationship between the source entity and that key
addNewRelationship = true;
}
}
else
{
// no entry exists, so we'll need to add a key along with the relationship
addKeyEntry = !IsForeignKey;
addNewRelationship = true;
}
if (addNewRelationship)
{
EntityKey ownerKey = ValidateOwnerWithRIConstraints(targetEntry == null ? null : targetEntry.WrappedEntity, value, checkBothEnds: true);
// Verify that the owner is in a valid state for adding a relationship
ValidateStateForAdd(this.WrappedOwner);
if (addKeyEntry)
{
manager.AddKeyEntry(value, targetEntitySet);
}
// First, clear any existing relationships
manager.TransactionManager.EntityBeingReparented = WrappedOwner.Entity;
try
{
ClearCollectionOrRef(null, null, /*doCascadeDelete*/ false);
}
finally
{
manager.TransactionManager.EntityBeingReparented = null;
}
// Then add the new one
if (IsForeignKey)
{
DetachedEntityKey = value;
// Update the FK values in this entity
if (IsDependentEndOfReferentialConstraint(false))
{
UpdateForeignKeyValues(WrappedOwner, value);
}
}
else
{
RelationshipWrapper wrapper = new RelationshipWrapper((AssociationSet)RelationshipSet, RelationshipNavigation.From, ownerKey, RelationshipNavigation.To, value);
// Add the relationship in the unchanged state if
EntityState relationshipState = EntityState.Added;
// If this is an unchanged/modified dependent end of a relationship and we are allowing the EntityKey to be set
// create the relationship in the Unchanged state because the state must "match" the dependent end state
if (!ownerKey.IsTemporary && IsDependentEndOfReferentialConstraint(false))
{
relationshipState = EntityState.Unchanged;
}
manager.AddNewRelation(wrapper, relationshipState);
}
}
}
}
else
{
// Just set the field for detached object -- during Attach/Add we will make sure this value
// is not in conflict if the EntityReference contains a real entity. We cannot always determine the
// EntityKey for any real entity in the detached state, so we don't bother to do it here.
DetachedEntityKey = value;
}
}
/// <summary>
/// This method is called when either the EntityKey or the Value property is set to null when it is
/// already null. For an FK association of a tracked entity the method will attempt to null FKs
/// thereby deleting the relationship. This may result in conceptual nulls being set.
/// </summary>
internal bool AttemptToNullFKsOnRefOrKeySetToNull()
{
if (ReferenceValue.Entity == null &&
WrappedOwner.Entity != null &&
WrappedOwner.Context != null &&
!UsingNoTracking &&
IsForeignKey)
{
// For identifying relationships, we throw, since we cannot set primary key values to null, unless
// the entity is in the Added state.
if (WrappedOwner.ObjectStateEntry.State != EntityState.Added &&
IsDependentEndOfReferentialConstraint(checkIdentifying: true))
{
throw EntityUtil.CannotChangeReferentialConstraintProperty();
}
// For unloaded FK relationships in the context we attempt to null FK values here, which will
// delete the relationship.
RemoveFromLocalCache(EntityWrapperFactory.NullWrapper, resetIsLoaded: true, preserveForeignKey: false);
return true;
}
return false;
}
internal EntityKey AttachedEntityKey
{
get
{
Debug.Assert(this.ObjectContext != null && !UsingNoTracking, "Should only need to access AttachedEntityKey property on attached EntityReferences");
return this.EntityKey;
}
}
internal EntityKey DetachedEntityKey
{
get
{
return _detachedEntityKey;
}
set
{
_detachedEntityKey = value;
}
}
internal EntityKey CachedForeignKey
{
get
{
return EntityKey ?? _cachedForeignKey;
}
}
internal void SetCachedForeignKey(EntityKey newForeignKey, EntityEntry source)
{
if (this.ObjectContext != null && this.ObjectContext.ObjectStateManager != null && // are we attached?
source != null && // do we have an entry?
_cachedForeignKey != null && !ForeignKeyFactory.IsConceptualNullKey(_cachedForeignKey) // do we have an fk?
&& _cachedForeignKey != newForeignKey) // is the FK different from the one that we already have?
{
this.ObjectContext.ObjectStateManager.RemoveEntryFromForeignKeyIndex(_cachedForeignKey, source);
}
_cachedForeignKey = newForeignKey;
}
internal IEnumerable<EntityKey> GetAllKeyValues()
{
if (EntityKey != null)
{
yield return EntityKey;
}
if (_cachedForeignKey != null)
{
yield return _cachedForeignKey;
}
if (_detachedEntityKey != null)
{
yield return _detachedEntityKey;
}
}
internal abstract IEntityWrapper CachedValue
{
get;
}
internal abstract IEntityWrapper ReferenceValue
{
get;
set;
}
internal EntityKey ValidateOwnerWithRIConstraints(IEntityWrapper targetEntity, EntityKey targetEntityKey, bool checkBothEnds)
{
EntityKey ownerKey = WrappedOwner.EntityKey;
// Check if Referential Constraints are violated
if ((object)ownerKey != null &&
!ownerKey.IsTemporary &&
IsDependentEndOfReferentialConstraint(checkIdentifying: true))
{
Debug.Assert(CachedForeignKey != null || EntityKey == null, "CachedForeignKey should not be null if EntityKey is not null.");
ValidateSettingRIConstraints(targetEntity,
targetEntityKey == null,
(this.CachedForeignKey != null && this.CachedForeignKey != targetEntityKey));
}
else if (checkBothEnds && targetEntity != null && targetEntity.Entity != null)
{
EntityReference otherEnd = GetOtherEndOfRelationship(targetEntity) as EntityReference;
if (otherEnd != null)
{
otherEnd.ValidateOwnerWithRIConstraints(WrappedOwner, ownerKey, checkBothEnds: false);
}
}
return ownerKey;
}
internal void ValidateSettingRIConstraints(IEntityWrapper targetEntity, bool settingToNull, bool changingForeignKeyValue)
{
bool isNoTracking = targetEntity != null && targetEntity.MergeOption == MergeOption.NoTracking;
if (settingToNull || // setting the principle to null
changingForeignKeyValue || // existing key does not match incoming key
(targetEntity != null &&
!isNoTracking &&
(targetEntity.ObjectStateEntry == null || // setting to a detached principle
(EntityKey == null && targetEntity.ObjectStateEntry.State == EntityState.Deleted || // setting to a deleted principle
(CachedForeignKey == null && targetEntity.ObjectStateEntry.State == EntityState.Added))))) // setting to an added principle
{
throw EntityUtil.CannotChangeReferentialConstraintProperty();
}
}
/// <summary>
/// EntityReferences can only deferred load if they are empty
/// </summary>
internal override bool CanDeferredLoad
{
get
{
return IsEmpty();
}
}
/// <summary>
/// Takes key values from the given principal entity and transfers them to the foreign key properties
/// of the dependant entry. This method requires a context, but does not require that either
/// entity is in the context. This allows it to work in NoTracking cases where we have the context
/// but we're not tracked by that context.
/// </summary>
/// <param name="dependentEntity">The entity into which foreign key values will be written</param>
/// <param name="principalEntity">The entity from which key values will be obtained</param>
/// <param name="changedFKs">If non-null, then keeps track of FKs that have already been set such that an exception can be thrown if we find conflicting values</param>
/// <param name="forceChange">If true, then the property setter is called even if FK values already match,
/// which causes the FK properties to be marked as modified.</param>
internal void UpdateForeignKeyValues(IEntityWrapper dependentEntity, IEntityWrapper principalEntity, Dictionary<int, object> changedFKs, bool forceChange)
{
Debug.Assert(dependentEntity.Entity != null, "dependentEntity.Entity == null");
Debug.Assert(principalEntity.Entity != null, "principalEntity.Entity == null");
Debug.Assert(this.IsForeignKey, "cannot update foreign key values if the relationship is not a FK");
ReferentialConstraint constraint = ((AssociationType)this.RelationMetadata).ReferentialConstraints[0];
Debug.Assert(constraint != null, "null constraint");
bool isUnchangedDependent = (object)WrappedOwner.EntityKey != null &&
!WrappedOwner.EntityKey.IsTemporary &&
IsDependentEndOfReferentialConstraint(checkIdentifying: true);
ObjectStateManager stateManager = ObjectContext.ObjectStateManager;
stateManager.TransactionManager.BeginForeignKeyUpdate(this);
try
{
EntitySet principalEntitySet = ((AssociationSet)RelationshipSet).AssociationSetEnds[ToEndMember.Name].EntitySet;
StateManagerTypeMetadata principalTypeMetadata = stateManager.GetOrAddStateManagerTypeMetadata(principalEntity.IdentityType, principalEntitySet);
EntitySet dependentEntitySet = ((AssociationSet)RelationshipSet).AssociationSetEnds[FromEndProperty.Name].EntitySet;
StateManagerTypeMetadata dependentTypeMetadata = stateManager.GetOrAddStateManagerTypeMetadata(dependentEntity.IdentityType, dependentEntitySet);
var principalProps = constraint.FromProperties;
int numValues = principalProps.Count;
string[] keyNames = null;
object[] values = null;
if (numValues > 1)
{
keyNames = principalEntitySet.ElementType.KeyMemberNames;
values = new object[numValues];
}
for (int i = 0; i < numValues; i++)
{
int principalOrdinal = principalTypeMetadata.GetOrdinalforOLayerMemberName(principalProps[i].Name);
object value = principalTypeMetadata.Member(principalOrdinal).GetValue(principalEntity.Entity);
int dependentOrdinal = dependentTypeMetadata.GetOrdinalforOLayerMemberName(constraint.ToProperties[i].Name);
bool valueChanging = !ByValueEqualityComparer.Default.Equals(dependentTypeMetadata.Member(dependentOrdinal).GetValue(dependentEntity.Entity), value);
if (forceChange || valueChanging)
{
if (isUnchangedDependent)
{
ValidateSettingRIConstraints(principalEntity, settingToNull: value == null, changingForeignKeyValue: valueChanging);
}
// If we're tracking FK values that have already been set, then compare the value we are about to set
// to the value we previously set for this ordinal, if such a value exists. If they don't match then
// it means that we got conflicting FK values from two different PKs and we should throw.
if (changedFKs != null)
{
object previouslySetValue;
if (changedFKs.TryGetValue(dependentOrdinal, out previouslySetValue))
{
if (!ByValueEqualityComparer.Default.Equals(previouslySetValue, value))
{
throw new InvalidOperationException(System.Data.Entity.Strings.Update_ReferentialConstraintIntegrityViolation);
}
}
else
{
changedFKs[dependentOrdinal] = value;
}
}
dependentEntity.SetCurrentValue(
dependentEntity.ObjectStateEntry,
dependentTypeMetadata.Member(dependentOrdinal),
-1,
dependentEntity.Entity,
value);
}
if (numValues > 1)
{
int keyIndex = Array.IndexOf(keyNames, principalProps[i].Name);
Debug.Assert(keyIndex >= 0 && keyIndex < numValues, "Could not find constraint prop name in entity set key names");
values[keyIndex] = value;
}
else
{
SetCachedForeignKey(new EntityKey(principalEntitySet, value), dependentEntity.ObjectStateEntry);
}
}
if (numValues > 1)
{
SetCachedForeignKey(new EntityKey(principalEntitySet, values), dependentEntity.ObjectStateEntry);
}
if (WrappedOwner.ObjectStateEntry != null)
{
stateManager.ForgetEntryWithConceptualNull(WrappedOwner.ObjectStateEntry, resetAllKeys: false);
}
}
finally
{
stateManager.TransactionManager.EndForeignKeyUpdate();
}
}
/// <summary>
/// Takes key values from the given principal key and transfers them to the foreign key properties
/// of the dependant entry. This method requires a context, but does not require that either
/// entity or key is in the context. This allows it to work in NoTracking cases where we have the context
/// but we're not tracked by that context.
/// </summary>
/// <param name="dependentEntity">The entity into which foreign key values will be written</param>
/// <param name="principalEntity">The key from which key values will be obtained</param>
internal void UpdateForeignKeyValues(IEntityWrapper dependentEntity, EntityKey principalKey)
{
Debug.Assert(dependentEntity.Entity != null, "dependentEntity.Entity == null");
Debug.Assert(principalKey != null, "principalKey == null");
Debug.Assert(!principalKey.IsTemporary, "Cannot update from a temp key");
Debug.Assert(this.IsForeignKey, "cannot update foreign key values if the relationship is not a FK");
ReferentialConstraint constraint = ((AssociationType)this.RelationMetadata).ReferentialConstraints[0];
Debug.Assert(constraint != null, "null constraint");
ObjectStateManager stateManager = ObjectContext.ObjectStateManager;
stateManager.TransactionManager.BeginForeignKeyUpdate(this);
try
{
EntitySet dependentEntitySet = ((AssociationSet)RelationshipSet).AssociationSetEnds[FromEndProperty.Name].EntitySet;
StateManagerTypeMetadata dependentTypeMetadata = stateManager.GetOrAddStateManagerTypeMetadata(dependentEntity.IdentityType, dependentEntitySet);
for (int i = 0; i < constraint.FromProperties.Count; i++)
{
object value = principalKey.FindValueByName(constraint.FromProperties[i].Name);
int dependentOrdinal = dependentTypeMetadata.GetOrdinalforOLayerMemberName(constraint.ToProperties[i].Name);
object currentValue = dependentTypeMetadata.Member(dependentOrdinal).GetValue(dependentEntity.Entity);
if (!ByValueEqualityComparer.Default.Equals(currentValue, value))
{
dependentEntity.SetCurrentValue(
dependentEntity.ObjectStateEntry,
dependentTypeMetadata.Member(dependentOrdinal),
-1,
dependentEntity.Entity,
value);
}
}
SetCachedForeignKey(principalKey, dependentEntity.ObjectStateEntry);
if (WrappedOwner.ObjectStateEntry != null)
{
stateManager.ForgetEntryWithConceptualNull(WrappedOwner.ObjectStateEntry, resetAllKeys: false);
}
}
finally
{
stateManager.TransactionManager.EndForeignKeyUpdate();
}
}
internal object GetDependentEndOfReferentialConstraint(object relatedValue)
{
return IsDependentEndOfReferentialConstraint(checkIdentifying: false) ?
WrappedOwner.Entity :
relatedValue;
}
internal bool NavigationPropertyIsNullOrMissing()
{
Debug.Assert(RelationshipNavigation != null, "null RelationshipNavigation");
return !TargetAccessor.HasProperty || WrappedOwner.GetNavigationPropertyValue(this) == null;
}
/// <summary>
/// Attempts to null all FKs associated with the dependent end of this relationship on this entity.
/// This may result in setting conceptual nulls if the FK is not nullable.
/// </summary>
internal void NullAllForeignKeys()
{
Debug.Assert(ObjectContext != null, "Nulling FKs only works when attached.");
Debug.Assert(IsForeignKey, "Cannot null FKs for independent associations.");
ObjectStateManager stateManager = ObjectContext.ObjectStateManager;
EntityEntry entry = WrappedOwner.ObjectStateEntry;
TransactionManager transManager = stateManager.TransactionManager;
if (!transManager.IsGraphUpdate && !transManager.IsAttachTracking && !transManager.IsRelatedEndAdd)
{
ReferentialConstraint constraint = ((AssociationType)RelationMetadata).ReferentialConstraints.Single();
if (TargetRoleName == constraint.FromRole.Name) // Only do this on the dependent end
{
if (transManager.IsDetaching)
{
// If the principal is being detached, then the dependent must be added back to the
// dangling keys index.
// Perf note: The dependent currently gets added when it is being detached and is then
// removed again later in the process. The code could be optimized to prevent this.
Debug.Assert(entry != null, "State entry must exist while detaching.");
EntityKey foreignKey = ForeignKeyFactory.CreateKeyFromForeignKeyValues(entry, this);
if (foreignKey != null)
{
stateManager.AddEntryContainingForeignKeyToIndex(foreignKey, entry);
}
}
else if (!ReferenceEquals(stateManager.EntityInvokingFKSetter, WrappedOwner.Entity) && !transManager.IsForeignKeyUpdate)
{
transManager.BeginForeignKeyUpdate(this);
try
{
bool unableToNull = true;
bool canSetModifiedProps = entry != null && (entry.State == EntityState.Modified || entry.State == EntityState.Unchanged);
EntitySet dependentEntitySet = ((AssociationSet)RelationshipSet).AssociationSetEnds[FromEndProperty.Name].EntitySet;
StateManagerTypeMetadata dependentTypeMetadata = stateManager.GetOrAddStateManagerTypeMetadata(WrappedOwner.IdentityType, dependentEntitySet);
for (int i = 0; i < constraint.FromProperties.Count; i++)
{
string propertyName = constraint.ToProperties[i].Name;
int dependentOrdinal = dependentTypeMetadata.GetOrdinalforOLayerMemberName(propertyName);
StateManagerMemberMetadata member = dependentTypeMetadata.Member(dependentOrdinal);
// This is a check for nullability in o-space. However, o-space nullability is not the
// same as nullability of the underlying type. In particular, one difference is that when
// attribute-based mapping is used then a property can be marked as not nullable in o-space
// even when the underlying CLR type is nullable. For such a case, we treat the property
// as if it were not nullable (since that's what we have shipped) even though we could
// technically set it to null.
if (member.ClrMetadata.Nullable)
{
// Only set the value to null if it is not already null.
if (member.GetValue(WrappedOwner.Entity) != null)
{
WrappedOwner.SetCurrentValue(
WrappedOwner.ObjectStateEntry,
dependentTypeMetadata.Member(dependentOrdinal),
-1,
WrappedOwner.Entity,
null);
}
else
{
// Given that the current value is null, this next check confirms that the original
// value is also null. If it isn't, then we must make sure that the entity is marked
// as modified.
// This case can happen because fixup in the entity can set the FK to null while processing
// a RelatedEnd operation. This will be detected by DetectChanges, but when performing
// RelatedEnd operations the user is not required to call DetectChanges.
if (canSetModifiedProps && WrappedOwner.ObjectStateEntry.OriginalValues.GetValue(dependentOrdinal) != null)
{
entry.SetModifiedProperty(propertyName);
}
}
unableToNull = false;
}
else if (canSetModifiedProps)
{
entry.SetModifiedProperty(propertyName);
}
}
if (unableToNull)
{
// We were unable to null out the FK because all FK properties were non-nullable.
// We need to keep track of this state so that we treat the FK as null even though
// we were not able to null it. This prevents the FK from being used for fixup and
// also causes an exception to be thrown if an attempt is made to commit in this state.
//We should only set a conceptual null if the entity is tracked
if (entry != null)
{
//The CachedForeignKey may be null if we are putting
//back a Conceptual Null as part of roll back
EntityKey realKey = CachedForeignKey;
if (realKey == null)
{
realKey = ForeignKeyFactory.CreateKeyFromForeignKeyValues(entry, this);
}
// Note that the realKey can still be null here for a situation where the key is marked not nullable
// in o-space and yet the underlying type is nullable and the entity has been added or attached with a null
// value for the property. This will cause SaveChanges to throw unless the entity is marked
// as deleted before SaveChanges is called, in which case we don't want to set a conceptual
// null here as the call might very well succeed in the database since, unless the FK is
// a concurrency token, the value we have for it is not used at all for the delete.
if (realKey != null)
{
SetCachedForeignKey(ForeignKeyFactory.CreateConceptualNullKey(realKey), entry);
stateManager.RememberEntryWithConceptualNull(entry);
}
}
}
else
{
SetCachedForeignKey(null, entry);
}
}
finally
{
transManager.EndForeignKeyUpdate();
}
}
}
}
}
}
}
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