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//---------------------------------------------------------------------
// <copyright file="RelationshipNavigation.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//
// @owner Microsoft
// @backupOwner Microsoft
//---------------------------------------------------------------------
using System;
using System.Collections.Generic;
using System.Data.Common;
using System.Globalization;
using System.Text;
using System.Data.Metadata.Edm;
namespace System.Data.Objects.DataClasses
{
/// <summary>
/// This class describes a relationship navigation from the
/// navigation property on one entity to another entity. It is
/// used throughout the collections and refs system to describe a
/// relationship and to connect from the navigation property on
/// one end of a relationship to the navigation property on the
/// other end.
/// </summary>
[Serializable]
internal class RelationshipNavigation
{
// ------------
// Constructors
// ------------
/// <summary>
/// Creates a navigation object with the given relationship
/// name, role name for the source and role name for the
/// destination.
/// </summary>
/// <param name="relationshipName">Canonical-space name of the relationship.</param>
/// <param name="from">Name of the role which is the source of the navigation.</param>
/// <param name="to">Name of the role which is the destination of the navigation.</param>
/// <param name="fromAccessor">The navigation property which is the source of the navigation.</param>
/// <param name="toAccessor">The navigation property which is the destination of the navigation.</param>
internal RelationshipNavigation(string relationshipName, string from, string to, NavigationPropertyAccessor fromAccessor, NavigationPropertyAccessor toAccessor)
{
EntityUtil.CheckStringArgument(relationshipName, "relationshipName");
EntityUtil.CheckStringArgument(from, "from");
EntityUtil.CheckStringArgument(to, "to");
_relationshipName = relationshipName;
_from = from;
_to = to;
_fromAccessor = fromAccessor;
_toAccessor = toAccessor;
}
// ------
// 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.
private readonly string _relationshipName;
private readonly string _from;
private readonly string _to;
[NonSerialized]
private RelationshipNavigation _reverse;
[NonSerialized]
private NavigationPropertyAccessor _fromAccessor;
[NonSerialized]
private NavigationPropertyAccessor _toAccessor;
// ----------
// Properties
// ----------
/// <summary>
/// Canonical-space relationship name.
/// </summary>
internal string RelationshipName
{
get
{
return _relationshipName;
}
}
/// <summary>
/// Role name for the source of this navigation.
/// </summary>
internal string From
{
get
{
return _from;
}
}
/// <summary>
/// Role name for the destination of this navigation.
/// </summary>
internal string To
{
get
{
return _to;
}
}
/// <summary>
/// Navigation property name for the destination of this navigation.
/// NOTE: There is not a FromPropertyAccessor property on RelationshipNavigation because it is not currently accessed anywhere
/// It is only used to calculate the "reverse" RelationshipNavigation.
/// </summary>
internal NavigationPropertyAccessor ToPropertyAccessor
{
get { return _toAccessor; }
}
internal bool IsInitialized
{
get { return _toAccessor != null && _fromAccessor != null; }
}
internal void InitializeAccessors(NavigationPropertyAccessor fromAccessor, NavigationPropertyAccessor toAccessor)
{
_fromAccessor = fromAccessor;
_toAccessor = toAccessor;
}
/// <summary>
/// The "reverse" version of this navigation.
/// </summary>
internal RelationshipNavigation Reverse
{
get
{
if (_reverse == null || !_reverse.IsInitialized)
{
// the reverse relationship is exactly like this
// one but from & to are switched
_reverse = new RelationshipNavigation(_relationshipName, _to, _from, _toAccessor, _fromAccessor);
}
return _reverse;
}
}
/// <summary>
/// Compares this instance to a given Navigation by their values.
/// </summary>
public override bool Equals(object obj)
{
RelationshipNavigation compareTo = obj as RelationshipNavigation;
return ((this == compareTo)
|| ((null != this) && (null != compareTo)
&& (this.RelationshipName == compareTo.RelationshipName)
&& (this.From == compareTo.From)
&& (this.To == compareTo.To)));
}
/// <summary>
/// Returns a value-based hash code.
/// </summary>
/// <returns>the hash value of this Navigation</returns>
public override int GetHashCode()
{
return this.RelationshipName.GetHashCode();
}
// -------
// Methods
// -------
/// <summary>
/// ToString is provided to simplify debugging, etc.
/// </summary>
public override string ToString()
{
return String.Format(CultureInfo.InvariantCulture,
"RelationshipNavigation: ({0},{1},{2})",
_relationshipName,
_from,
_to);
}
}
}
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