411 lines
14 KiB
C#
411 lines
14 KiB
C#
/* Copyright (C) 2008 - 2011 Jordan Marr
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 3 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library. If not, see <http://www.gnu.org/licenses/>. */
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using System;
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using System.Collections;
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using System.Collections.Generic;
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using System.Text;
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using System.Data;
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using System.Data.Common;
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using System.Linq;
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using Marr.Data.Mapping;
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using System.Reflection;
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namespace Marr.Data
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{
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/// <summary>
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/// Holds metadata about an object graph that is being queried and eagerly loaded.
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/// Contains all metadata needed to instantiate the object and fill it with data from a DataReader.
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/// Does not iterate through lazy loaded child relationships.
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/// </summary>
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internal class EntityGraph : IEnumerable<EntityGraph>
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{
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private MapRepository _repos;
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private EntityGraph _parent;
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private Type _entityType;
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private Relationship _relationship;
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private ColumnMapCollection _columns;
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private RelationshipCollection _relationships;
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private List<EntityGraph> _children;
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private object _entity;
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private GroupingKeyCollection _groupingKeyColumns;
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private Dictionary<string, EntityReference> _entityReferences;
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internal IList RootList { get; private set; }
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internal bool IsParentReference { get; private set; }
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/// <summary>
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/// Recursively builds an entity graph of the given parent type.
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/// </summary>
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/// <param name="entityType"></param>
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public EntityGraph(Type entityType, IList rootList)
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: this(entityType, null, null) // Recursively constructs hierarchy
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{
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RootList = rootList;
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}
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/// <summary>
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/// Recursively builds entity graph hierarchy.
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/// </summary>
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/// <param name="entityType"></param>
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/// <param name="parent"></param>
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/// <param name="relationship"></param>
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private EntityGraph(Type entityType, EntityGraph parent, Relationship relationship)
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{
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_repos = MapRepository.Instance;
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_entityType = entityType;
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_parent = parent;
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_relationship = relationship;
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IsParentReference = !IsRoot && AnyParentsAreOfType(entityType);
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if (!IsParentReference)
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{
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_columns = _repos.GetColumns(entityType);
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}
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_relationships = _repos.GetRelationships(entityType);
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_children = new List<EntityGraph>();
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Member = relationship != null ? relationship.Member : null;
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_entityReferences = new Dictionary<string, EntityReference>();
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if (IsParentReference)
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{
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return;
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}
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// Create a new EntityGraph for each child relationship that is not lazy loaded
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foreach (Relationship childRelationship in this.Relationships)
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{
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if (!childRelationship.IsLazyLoaded)
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{
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_children.Add(new EntityGraph(childRelationship.RelationshipInfo.EntityType, this, childRelationship));
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}
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}
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}
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public MemberInfo Member { get; private set; }
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/// <summary>
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/// Gets the parent of this EntityGraph.
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/// </summary>
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public EntityGraph Parent
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{
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get
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{
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return _parent;
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}
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}
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/// <summary>
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/// Gets the Type of this EntityGraph.
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/// </summary>
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public Type EntityType
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{
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get { return _entityType; }
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}
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/// <summary>
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/// Gets a boolean than indicates whether this entity is the root node in the graph.
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/// </summary>
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public bool IsRoot
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{
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get
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{
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return _parent == null;
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}
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}
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/// <summary>
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/// Gets a boolean that indicates whether this entity is a child.
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/// </summary>
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public bool IsChild
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{
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get
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{
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return _parent != null;
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}
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}
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/// <summary>
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/// Gets the columns mapped to this entity.
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/// </summary>
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public ColumnMapCollection Columns
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{
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get { return _columns; }
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}
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/// <summary>
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/// Gets the relationships mapped to this entity.
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/// </summary>
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public RelationshipCollection Relationships
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{
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get { return _relationships; }
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}
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/// <summary>
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/// A list of EntityGraph objects that hold metadata about the child entities that will be loaded.
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/// </summary>
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public List<EntityGraph> Children
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{
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get { return _children; }
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}
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/// <summary>
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/// Adds an entity to the appropriate place in the object graph.
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/// </summary>
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/// <param name="entityInstance"></param>
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public void AddEntity(object entityInstance)
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{
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_entity = entityInstance;
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// Add newly created entityInstance to list (Many) or set it to field (One)
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if (this.IsRoot)
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{
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RootList.Add(entityInstance);
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}
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else if (_relationship.RelationshipInfo.RelationType == RelationshipTypes.Many)
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{
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var list = _parent._entityReferences[_parent.GroupingKeyColumns.GroupingKey]
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.ChildLists[_relationship.Member.Name];
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list.Add(entityInstance);
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}
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else // RelationTypes.One
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{
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_repos.ReflectionStrategy.SetFieldValue(_parent._entity, _relationship.Member.Name, entityInstance);
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}
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EntityReference entityRef = new EntityReference(entityInstance);
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_entityReferences.Add(GroupingKeyColumns.GroupingKey, entityRef);
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InitOneToManyChildLists(entityRef);
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}
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/// <summary>
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/// Searches for a previously loaded parent entity and then sets that reference to the mapped Relationship property.
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/// </summary>
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public void AddParentReference()
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{
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var parentReference = FindParentReference();
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_repos.ReflectionStrategy.SetFieldValue(_parent._entity, _relationship.Member.Name, parentReference);
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}
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/// <summary>
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/// Concatenates the values of the GroupingKeys property and compares them
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/// against the LastKeyGroup property. Returns true if the values are different,
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/// or false if the values are the same.
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/// The currently concatenated keys are saved in the LastKeyGroup property.
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/// </summary>
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/// <param name="reader"></param>
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/// <returns></returns>
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public bool IsNewGroup(DbDataReader reader)
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{
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bool isNewGroup = false;
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// Get primary keys from parent entity and any one-to-one child entites
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GroupingKeyCollection groupingKeyColumns = this.GroupingKeyColumns;
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// Concatenate column values
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KeyGroupInfo keyGroupInfo = groupingKeyColumns.CreateGroupingKey(reader);
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if (!keyGroupInfo.HasNullKey && !_entityReferences.ContainsKey(keyGroupInfo.GroupingKey))
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{
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isNewGroup = true;
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}
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return isNewGroup;
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}
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/// <summary>
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/// Gets the GroupingKeys for this entity.
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/// GroupingKeys determine when to create and add a new entity to the graph.
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/// </summary>
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/// <remarks>
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/// A simple entity with no relationships will return only its PrimaryKey columns.
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/// A parent entity with one-to-one child relationships will include its own PrimaryKeys,
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/// and it will recursively traverse all Children with one-to-one relationships and add their PrimaryKeys.
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/// A child entity that has a one-to-one relationship with its parent will use the same
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/// GroupingKeys already defined by its parent.
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/// </remarks>
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public GroupingKeyCollection GroupingKeyColumns
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{
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get
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{
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if (_groupingKeyColumns == null)
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_groupingKeyColumns = GetGroupingKeyColumns();
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return _groupingKeyColumns;
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}
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}
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private bool AnyParentsAreOfType(Type type)
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{
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EntityGraph parent = _parent;
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while (parent != null)
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{
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if (parent._entityType == type)
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{
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return true;
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}
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parent = parent._parent;
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}
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return false;
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}
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private object FindParentReference()
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{
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var parent = this.Parent.Parent;
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while (parent != null)
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{
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if (parent._entityType == _relationship.MemberType)
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{
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return parent._entity;
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}
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parent = parent.Parent;
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}
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return null;
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}
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/// <summary>
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/// Initializes the owning lists on many-to-many Children.
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/// </summary>
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/// <param name="entityInstance"></param>
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private void InitOneToManyChildLists(EntityReference entityRef)
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{
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// Get a reference to the parent's the childrens' OwningLists to the parent entity
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for (int i = 0; i < Relationships.Count; i++)
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{
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Relationship relationship = Relationships[i];
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if (relationship.RelationshipInfo.RelationType == RelationshipTypes.Many)
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{
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try
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{
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IList list = (IList)_repos.ReflectionStrategy.CreateInstance(relationship.MemberType);
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_repos.ReflectionStrategy.SetFieldValue(entityRef.Entity, relationship.Member.Name, list);
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// Save a reference to each 1-M list
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entityRef.AddChildList(relationship.Member.Name, list);
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}
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catch (Exception ex)
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{
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throw new DataMappingException(
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string.Format("{0}.{1} is a \"Many\" relationship type so it must derive from IList.",
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entityRef.Entity.GetType().Name, relationship.Member.Name),
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ex);
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}
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}
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}
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}
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/// <summary>
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/// Gets a list of keys to group by.
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/// </summary>
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/// <remarks>
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/// When converting an unnormalized set of data from a database view,
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/// a new entity is only created when the grouping keys have changed.
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/// NOTE: This behavior works on the assumption that the view result set
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/// has been sorted by the root entity primary key(s), followed by the
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/// child entity primary keys.
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/// </remarks>
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/// <returns></returns>
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private GroupingKeyCollection GetGroupingKeyColumns()
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{
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// Get primary keys for this parent entity
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GroupingKeyCollection groupingKeyColumns = new GroupingKeyCollection();
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groupingKeyColumns.PrimaryKeys.AddRange(Columns.PrimaryKeys);
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// The following conditions should fail with an exception:
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// 1) Any parent entity (entity with children) must have at least one PK specified or an exception will be thrown
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// 2) All 1-M relationship entities must have at least one PK specified
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// * Only 1-1 entities with no children are allowed to have 0 PKs specified.
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if ((groupingKeyColumns.PrimaryKeys.Count == 0 && _children.Count > 0) ||
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(groupingKeyColumns.PrimaryKeys.Count == 0 && !IsRoot && _relationship.RelationshipInfo.RelationType == RelationshipTypes.Many))
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throw new MissingPrimaryKeyException(string.Format("There are no primary key mappings defined for the following entity: '{0}'.", this.EntityType.Name));
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// Add parent's keys
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if (IsChild)
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groupingKeyColumns.ParentPrimaryKeys.AddRange(Parent.GroupingKeyColumns);
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return groupingKeyColumns;
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}
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#region IEnumerable<EntityGraph> Members
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public IEnumerator<EntityGraph> GetEnumerator()
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{
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return TraverseGraph(this);
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}
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/// <summary>
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/// Recursively traverses through every entity in the EntityGraph.
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/// </summary>
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/// <param name="entityGraph"></param>
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/// <returns></returns>
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private static IEnumerator<EntityGraph> TraverseGraph(EntityGraph entityGraph)
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{
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Stack<EntityGraph> stack = new Stack<EntityGraph>();
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stack.Push(entityGraph);
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while (stack.Count > 0)
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{
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EntityGraph node = stack.Pop();
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yield return node;
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foreach (EntityGraph childGraph in node.Children)
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{
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stack.Push(childGraph);
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}
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}
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}
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#endregion
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#region IEnumerable Members
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IEnumerator IEnumerable.GetEnumerator()
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{
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return this.GetEnumerator();
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}
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#endregion
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}
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}
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public struct KeyGroupInfo
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{
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private string _groupingKey;
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private bool _hasNullKey;
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public KeyGroupInfo(string groupingKey, bool hasNullKey)
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{
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_groupingKey = groupingKey;
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_hasNullKey = hasNullKey;
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}
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public string GroupingKey
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{
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get { return _groupingKey; }
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}
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public bool HasNullKey
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{
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get { return _hasNullKey; }
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}
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}
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