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//---------------------------------------------------------------------
// <copyright file="AssociationSetMetadata.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//
// @owner Microsoft
// @backupOwner Microsoft
//---------------------------------------------------------------------
using System.Data.Metadata.Edm;
using System.Data.Common.Utils;
using System.Data.Common.CommandTrees;
using System.Collections.Generic;
using System.Linq;
namespace System.Data.Mapping.Update.Internal
{
/// <summary>
/// Encapsulates information about ends of an association set needed to correctly
/// interpret updates.
/// </summary>
internal sealed class AssociationSetMetadata
{
/// <summary>
/// Gets association ends that must be modified if the association
/// is changed (e.g. the mapping of the association is conditioned
/// on some property of the end)
/// </summary>
internal readonly Set<AssociationEndMember> RequiredEnds;
/// <summary>
/// Gets association ends that may be implicitly modified as a result
/// of changes to the association (e.g. collocated entity with server
/// generated value)
/// </summary>
internal readonly Set<AssociationEndMember> OptionalEnds;
/// <summary>
/// Gets association ends whose values may influence the association
/// (e.g. where there is a ReferentialIntegrity or "foreign key" constraint)
/// </summary>
internal readonly Set<AssociationEndMember> IncludedValueEnds;
/// <summary>
/// true iff. there are interesting ends for this association set.
/// </summary>
internal bool HasEnds
{
get { return 0 < RequiredEnds.Count || 0 < OptionalEnds.Count || 0 < IncludedValueEnds.Count; }
}
/// <summary>
/// Initialize Metadata for an AssociationSet
/// </summary>
internal AssociationSetMetadata(Set<EntitySet> affectedTables, AssociationSet associationSet, MetadataWorkspace workspace)
{
// If there is only 1 table, there can be no ambiguity about the "destination" of a relationship, so such
// sets are not typically required.
bool isRequired = 1 < affectedTables.Count;
// determine the ends of the relationship
var ends = associationSet.AssociationSetEnds;
// find collocated entities
foreach (EntitySet table in affectedTables)
{
// Find extents influencing the table
var influencingExtents = MetadataHelper.GetInfluencingEntitySetsForTable(table, workspace);
foreach (EntitySet influencingExtent in influencingExtents)
{
foreach (var end in ends)
{
// If the extent is an end of the relationship and we haven't already added it to the
// required set...
if (end.EntitySet.EdmEquals(influencingExtent))
{
if (isRequired)
{
AddEnd(ref RequiredEnds, end.CorrespondingAssociationEndMember);
}
else if (null == RequiredEnds || !RequiredEnds.Contains(end.CorrespondingAssociationEndMember))
{
AddEnd(ref OptionalEnds, end.CorrespondingAssociationEndMember);
}
}
}
}
}
// fix Required and Optional sets
FixSet(ref RequiredEnds);
FixSet(ref OptionalEnds);
// for associations with referential constraints, the principal end is always interesting
// since its key values may take precedence over the key values of the dependent end
foreach (ReferentialConstraint constraint in associationSet.ElementType.ReferentialConstraints)
{
// FromRole is the principal end in the referential constraint
AssociationEndMember principalEnd = (AssociationEndMember)constraint.FromRole;
if (!RequiredEnds.Contains(principalEnd) &&
!OptionalEnds.Contains(principalEnd))
{
AddEnd(ref IncludedValueEnds, principalEnd);
}
}
FixSet(ref IncludedValueEnds);
}
/// <summary>
/// Initialize given required ends.
/// </summary>
internal AssociationSetMetadata(IEnumerable<AssociationEndMember> requiredEnds)
{
if (requiredEnds.Any())
{
RequiredEnds = new Set<AssociationEndMember>(requiredEnds);
}
FixSet(ref RequiredEnds);
FixSet(ref OptionalEnds);
FixSet(ref IncludedValueEnds);
}
static private void AddEnd(ref Set<AssociationEndMember> set, AssociationEndMember element)
{
if (null == set)
{
set = new Set<AssociationEndMember>();
}
set.Add(element);
}
static private void FixSet(ref Set<AssociationEndMember> set)
{
if (null == set)
{
set = Set<AssociationEndMember>.Empty;
}
else
{
set.MakeReadOnly();
}
}
}
}
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