我父母和孩子之间的关系是他们通过边缘连接起来。它与有向图结构类似。
DAL：
public void SaveResource(Resource resource)
{
context.AddToResources(resource); //Should also add children.
context.SaveChanges();
}
public Resource GetResource(int resourceId)
{
var resource = (from r in context.Resources
.Include("ToEdges").Include("FromEdges")
where r.ResourceId == resourceId
select r).SingleOrDefault();
return resource;
}
服务：
public void AddChildResource(int parentResourceId, Resource childResource)
{
Resource parentResource = repository.GetResource(parentResourceId);
ResourceEdge inEdge = new ResourceEdge();
inEdge.ToResource = childResource;
parentResource.ToEdges.Add(inEdge);
repository.SaveResource(parentResource);
}
错误：ObjectStateManager中已存在具有相同键的对象。现有对象处于Unchanged状态。如果对象处于添加状态，则只能再次添加到ObjectStateManager。
图像：
alt text http://img100.imageshack.us/img100/374/entity.png
我被告知这是将孩子提交给已经存在的父母的顺序：
获取父级 - ＆gt;将孩子附加到父母 - ＆gt;提交父母。
这就是我使用的序列。上面的代码是使用存储库模式从ASP.NET MVC 2应用程序中提取的。
EDMX文件：
<?xml version="1.0" encoding="utf-8"?>
<edmx:Edmx Version="2.0" xmlns:edmx="http://schemas.microsoft.com/ado/2008/10/edmx">
<!-- EF Runtime content -->
<edmx:Runtime>
<!-- SSDL content -->
<edmx:StorageModels>
<Schema Namespace="XDbModel.Store" Alias="Self" Provider="System.Data.SqlClient" ProviderManifestToken="2008" xmlns:store="http://schemas.microsoft.com/ado/2007/12/edm/EntityStoreSchemaGenerator" xmlns="http://schemas.microsoft.com/ado/2009/02/edm/ssdl">
<EntityContainer Name="XDbModelStoreContainer">
<EntitySet Name="Bundles" EntityType="XDbModel.Store.Bundles" store:Type="Tables" Schema="dbo" />
<EntitySet Name="CellProviders" EntityType="XDbModel.Store.CellProviders" store:Type="Tables" Schema="dbo" />
<EntitySet Name="Comments" EntityType="XDbModel.Store.Comments" store:Type="Tables" Schema="dbo" />
<EntitySet Name="LocationPoints" EntityType="XDbModel.Store.LocationPoints" store:Type="Tables" Schema="dbo" />
<EntitySet Name="Locations" EntityType="XDbModel.Store.Locations" store:Type="Tables" Schema="dbo" />
<EntitySet Name="Offers" EntityType="XDbModel.Store.Offers" store:Type="Tables" Schema="dbo" />
<EntitySet Name="PostBundleJunction" EntityType="XDbModel.Store.PostBundleJunction" store:Type="Tables" Schema="dbo" />
<EntitySet Name="PostMedia" EntityType="XDbModel.Store.PostMedia" store:Type="Tables" Schema="dbo" />
<EntitySet Name="Posts" EntityType="XDbModel.Store.Posts" store:Type="Tables" Schema="dbo" />
<EntitySet Name="ResourceEdges" EntityType="XDbModel.Store.ResourceEdges" store:Type="Tables" Schema="dbo" />
<EntitySet Name="ResourceNames" EntityType="XDbModel.Store.ResourceNames" store:Type="Tables" Schema="dbo" />
<EntitySet Name="Resources" EntityType="XDbModel.Store.Resources" store:Type="Tables" Schema="dbo" />
<EntitySet Name="sysdiagrams" EntityType="XDbModel.Store.sysdiagrams" store:Type="Tables" Schema="dbo" />
<EntitySet Name="Users" EntityType="XDbModel.Store.Users" store:Type="Tables" Schema="dbo" />
<EntitySet Name="Votes" EntityType="XDbModel.Store.Votes" store:Type="Tables" Schema="dbo" />
<AssociationSet Name="FK_Comments_Offers" Association="XDbModel.Store.FK_Comments_Offers">
<End Role="Offers" EntitySet="Offers" />
<End Role="Comments" EntitySet="Comments" />
</AssociationSet>
<AssociationSet Name="FK_Comments_Users" Association="XDbModel.Store.FK_Comments_Users">
<End Role="Users" EntitySet="Users" />
<End Role="Comments" EntitySet="Comments" />
</AssociationSet>
<AssociationSet Name="FK_LocationPoints_Locations" Association="XDbModel.Store.FK_LocationPoints_Locations">
<End Role="Locations" EntitySet="Locations" />
<End Role="LocationPoints" EntitySet="LocationPoints" />
</AssociationSet>
<AssociationSet Name="FK_PostBundleJunction_Bundles" Association="XDbModel.Store.FK_PostBundleJunction_Bundles">
<End Role="Bundles" EntitySet="Bundles" />
<End Role="PostBundleJunction" EntitySet="PostBundleJunction" />
</AssociationSet>
<AssociationSet Name="FK_PostBundleJunction_Posts" Association="XDbModel.Store.FK_PostBundleJunction_Posts">
<End Role="Posts" EntitySet="Posts" />
<End Role="PostBundleJunction" EntitySet="PostBundleJunction" />
</AssociationSet>
<AssociationSet Name="FK_Posts_Locations" Association="XDbModel.Store.FK_Posts_Locations">
<End Role="Locations" EntitySet="Locations" />
<End Role="Posts" EntitySet="Posts" />
</AssociationSet>
<AssociationSet Name="FK_Posts_ResourceNames" Association="XDbModel.Store.FK_Posts_ResourceNames">
<End Role="ResourceNames" EntitySet="ResourceNames" />
<End Role="Posts" EntitySet="Posts" />
</AssociationSet>
<AssociationSet Name="FK_Posts_Users" Association="XDbModel.Store.FK_Posts_Users">
<End Role="Users" EntitySet="Users" />
<End Role="Posts" EntitySet="Posts" />
</AssociationSet>
<AssociationSet Name="FK_ResourceEdges_Resources" Association="XDbModel.Store.FK_ResourceEdges_Resources">
<End Role="Resources" EntitySet="Resources" />
<End Role="ResourceEdges" EntitySet="ResourceEdges" />
</AssociationSet>
<AssociationSet Name="FK_ResourceEdges_Resources1" Association="XDbModel.Store.FK_ResourceEdges_Resources1">
<End Role="Resources" EntitySet="Resources" />
<End Role="ResourceEdges" EntitySet="ResourceEdges" />
</AssociationSet>
<AssociationSet Name="FK_ResourceNames_Resources" Association="XDbModel.Store.FK_ResourceNames_Resources">
<End Role="Resources" EntitySet="Resources" />
<End Role="ResourceNames" EntitySet="ResourceNames" />
</AssociationSet>
<AssociationSet Name="FK_Users_Locations" Association="XDbModel.Store.FK_Users_Locations">
<End Role="Locations" EntitySet="Locations" />
<End Role="Users" EntitySet="Users" />
</AssociationSet>
<AssociationSet Name="FK_Votes_Posts" Association="XDbModel.Store.FK_Votes_Posts">
<End Role="Posts" EntitySet="Posts" />
<End Role="Votes" EntitySet="Votes" />
</AssociationSet>
</EntityContainer>
<EntityType Name="Bundles">
<Key>
<PropertyRef Name="BundleId" />
</Key>
<Property Name="BundleId" Type="int" Nullable="false" />
</EntityType>
<EntityType Name="CellProviders">
<Key>
<PropertyRef Name="CellProviderID" />
</Key>
<Property Name="CellProviderID" Type="uniqueidentifier" Nullable="false" />
</EntityType>
<EntityType Name="Comments">
<Key>
<PropertyRef Name="CommentID" />
</Key>
<Property Name="CommentID" Type="uniqueidentifier" Nullable="false" />
<Property Name="ParentPostID" Type="uniqueidentifier" />
<Property Name="OfferPostID" Type="uniqueidentifier" />
<Property Name="UserID" Type="uniqueidentifier" Nullable="false" />
</EntityType>
<EntityType Name="LocationPoints">
<Key>
<PropertyRef Name="LocationPointId" />
</Key>
<Property Name="LocationPointId" Type="int" Nullable="false" StoreGeneratedPattern="Identity" />
<Property Name="Latitude" Type="float" Nullable="false" />
<Property Name="Longitude" Type="float" Nullable="false" />
<Property Name="Altitude" Type="float" Nullable="false" />
<Property Name="Count" Type="int" Nullable="false" />
<Property Name="LocationId" Type="int" Nullable="false" />
</EntityType>
<EntityType Name="Locations">
<Key>
<PropertyRef Name="LocationId" />
</Key>
<Property Name="LocationId" Type="int" Nullable="false" StoreGeneratedPattern="Identity" />
<Property Name="Address1" Type="nvarchar" Nullable="false" MaxLength="200" />
<Property Name="Address2" Type="nvarchar" MaxLength="200" />
<Property Name="Address3" Type="nvarchar" MaxLength="200" />
<Property Name="State" Type="nvarchar" Nullable="false" MaxLength="200" />
<Property Name="Country" Type="nvarchar" Nullable="false" MaxLength="200" />
</EntityType>
<EntityType Name="Offers">
<Key>
<PropertyRef Name="OfferID" />
</Key>
<Property Name="OfferID" Type="uniqueidentifier" Nullable="false" />
<Property Name="NeedOffer" Type="uniqueidentifier" Nullable="false" />
<Property Name="ProvisionOffer" Type="uniqueidentifier" Nullable="false" />
</EntityType>
<EntityType Name="PostBundleJunction">
<Key>
<PropertyRef Name="BundleId" />
<PropertyRef Name="PostId" />
</Key>
<Property Name="BundleId" Type="int" Nullable="false" />
<Property Name="PostId" Type="int" Nullable="false" />
</EntityType>
<EntityType Name="PostMedia">
<Key>
<PropertyRef Name="MediaId" />
</Key>
<Property Name="MediaId" Type="int" Nullable="false" StoreGeneratedPattern="Identity" />
<Property Name="MediaExt" Type="nvarchar" Nullable="false" MaxLength="5" />
<Property Name="PostId" Type="int" Nullable="false" />
<Property Name="SynthId" Type="uniqueidentifier" />
</EntityType>
<EntityType Name="Posts">
<Key>
<PropertyRef Name="PostId" />
</Key>
<Property Name="PostId" Type="int" Nullable="false" StoreGeneratedPattern="Identity" />
<Property Name="PosterID" Type="uniqueidentifier" Nullable="false" />
<Property Name="BundleId" Type="int" Nullable="false" />
<Property Name="LocationId" Type="int" Nullable="false" />
<Property Name="Tags" Type="uniqueidentifier" />
<Property Name="Quanitity" Type="int" Nullable="false" />
<Property Name="Description" Type="text" Nullable="false" />
<Property Name="ResourceNameId" Type="int" Nullable="false" />
<Property Name="Date" Type="datetime" Nullable="false" />
</EntityType>
<EntityType Name="ResourceEdges">
<Key>
<PropertyRef Name="EdgeId" />
</Key>
<Property Name="Rank" Type="int" Nullable="false" />
<Property Name="EdgeId" Type="int" Nullable="false" StoreGeneratedPattern="Identity" />
<Property Name="ToResourceId" Type="int" Nullable="false" />
<Property Name="FromResourrceId" Type="int" Nullable="false" />
</EntityType>
<EntityType Name="ResourceNames">
<Key>
<PropertyRef Name="ResourceNameId" />
</Key>
<Property Name="ResourceNameId" Type="int" Nullable="false" StoreGeneratedPattern="Identity" />
<Property Name="Name" Type="nvarchar" Nullable="false" MaxLength="100" />
<Property Name="ResourceId" Type="int" Nullable="false" />
</EntityType>
<EntityType Name="Resources">
<Key>
<PropertyRef Name="ResourceId" />
</Key>
<Property Name="ResourceId" Type="int" Nullable="false" StoreGeneratedPattern="Identity" />
<Property Name="Description" Type="nvarchar" MaxLength="50" />
</EntityType>
<EntityType Name="sysdiagrams">
<Key>
<PropertyRef Name="diagram_id" />
</Key>
<Property Name="name" Type="nvarchar" Nullable="false" MaxLength="128" />
<Property Name="principal_id" Type="int" Nullable="false" />
<Property Name="diagram_id" Type="int" Nullable="false" StoreGeneratedPattern="Identity" />
<Property Name="version" Type="int" />
<Property Name="definition" Type="varbinary(max)" />
</EntityType>
<EntityType Name="Users">
<Key>
<PropertyRef Name="UserID" />
</Key>
<Property Name="UserID" Type="uniqueidentifier" Nullable="false" />
<Property Name="LocationId" Type="int" />
</EntityType>
<EntityType Name="Votes">
<Key>
<PropertyRef Name="VoteId" />
</Key>
<Property Name="VoteId" Type="int" Nullable="false" />
<Property Name="VoterId" Type="uniqueidentifier" Nullable="false" />
<Property Name="VoteContent" Type="int" Nullable="false" />
<Property Name="PostId" Type="int" Nullable="false" />
</EntityType>
<Association Name="FK_Comments_Offers">
<End Role="Offers" Type="XDbModel.Store.Offers" Multiplicity="0..1" />
<End Role="Comments" Type="XDbModel.Store.Comments" Multiplicity="*" />
<ReferentialConstraint>
<Principal Role="Offers">
<PropertyRef Name="OfferID" />
</Principal>
<Dependent Role="Comments">
<PropertyRef Name="OfferPostID" />
</Dependent>
</ReferentialConstraint>
</Association>
<Association Name="FK_Comments_Users">
<End Role="Users" Type="XDbModel.Store.Users" Multiplicity="1">
<OnDelete Action="Cascade" />
</End>
<End Role="Comments" Type="XDbModel.Store.Comments" Multiplicity="*" />
<ReferentialConstraint>
<Principal Role="Users">
<PropertyRef Name="UserID" />
</Principal>
<Dependent Role="Comments">
<PropertyRef Name="UserID" />
</Dependent>
</ReferentialConstraint>
</Association>
<Association Name="FK_LocationPoints_Locations">
<End Role="Locations" Type="XDbModel.Store.Locations" Multiplicity="1">
<OnDelete Action="Cascade" />
</End>
<End Role="LocationPoints" Type="XDbModel.Store.LocationPoints" Multiplicity="*" />
<ReferentialConstraint>
<Principal Role="Locations">
<PropertyRef Name="LocationId" />
</Principal>
<Dependent Role="LocationPoints">
<PropertyRef Name="LocationId" />
</Dependent>
</ReferentialConstraint>
</Association>
<Association Name="FK_PostBundleJunction_Bundles">
<End Role="Bundles" Type="XDbModel.Store.Bundles" Multiplicity="1" />
<End Role="PostBundleJunction" Type="XDbModel.Store.PostBundleJunction" Multiplicity="*" />
<ReferentialConstraint>
<Principal Role="Bundles">
<PropertyRef Name="BundleId" />
</Principal>
<Dependent Role="PostBundleJunction">
<PropertyRef Name="BundleId" />
</Dependent>
</ReferentialConstraint>
</Association>
<Association Name="FK_PostBundleJunction_Posts">
<End Role="Posts" Type="XDbModel.Store.Posts" Multiplicity="1" />
<End Role="PostBundleJunction" Type="XDbModel.Store.PostBundleJunction" Multiplicity="*" />
<ReferentialConstraint>
<Principal Role="Posts">
<PropertyRef Name="PostId" />
</Principal>
<Dependent Role="PostBundleJunction">
<PropertyRef Name="PostId" />
</Dependent>
</ReferentialConstraint>
</Association>
<Association Name="FK_Posts_Locations">
<End Role="Locations" Type="XDbModel.Store.Locations" Multiplicity="1" />
<End Role="Posts" Type="XDbModel.Store.Posts" Multiplicity="*" />
<ReferentialConstraint>
<Principal Role="Locations">
<PropertyRef Name="LocationId" />
</Principal>
<Dependent Role="Posts">
<PropertyRef Name="LocationId" />
</Dependent>
</ReferentialConstraint>
</Association>
<Association Name="FK_Posts_ResourceNames">
<End Role="ResourceNames" Type="XDbModel.Store.ResourceNames" Multiplicity="1" />
<End Role="Posts" Type="XDbModel.Store.Posts" Multiplicity="*" />
<ReferentialConstraint>
<Principal Role="ResourceNames">
<PropertyRef Name="ResourceNameId" />
</Principal>
<Dependent Role="Posts">
<PropertyRef Name="ResourceNameId" />
</Dependent>
</ReferentialConstraint>
</Association>
<Association Name="FK_Posts_Users">
<End Role="Users" Type="XDbModel.Store.Users" Multiplicity="1" />
<End Role="Posts" Type="XDbModel.Store.Posts" Multiplicity="*" />
<ReferentialConstraint>
<Principal Role="Users">
<PropertyRef Name="UserID" />
</Principal>
<Dependent Role="Posts">
<PropertyRef Name="PosterID" />
</Dependent>
</ReferentialConstraint>
</Association>
<Association Name="FK_ResourceEdges_Resources">
<End Role="Resources" Type="XDbModel.Store.Resources" Multiplicity="1" />
<End Role="ResourceEdges" Type="XDbModel.Store.ResourceEdges" Multiplicity="*" />
<ReferentialConstraint>
<Principal Role="Resources">
<PropertyRef Name="ResourceId" />
</Principal>
<Dependent Role="ResourceEdges">
<PropertyRef Name="ToResourceId" />
</Dependent>
</ReferentialConstraint>
</Association>
<Association Name="FK_ResourceEdges_Resources1">
<End Role="Resources" Type="XDbModel.Store.Resources" Multiplicity="1" />
<End Role="ResourceEdges" Type="XDbModel.Store.ResourceEdges" Multiplicity="*" />
<ReferentialConstraint>
<Principal Role="Resources">
<PropertyRef Name="ResourceId" />
</Principal>
<Dependent Role="ResourceEdges">
<PropertyRef Name="FromResourrceId" />
</Dependent>
</ReferentialConstraint>
</Association>
<Association Name="FK_ResourceNames_Resources">
<End Role="Resources" Type="XDbModel.Store.Resources" Multiplicity="1">
<OnDelete Action="Cascade" />
</End>
<End Role="ResourceNames" Type="XDbModel.Store.ResourceNames" Multiplicity="*" />
<ReferentialConstraint>
<Principal Role="Resources">
<PropertyRef Name="ResourceId" />
</Principal>
<Dependent Role="ResourceNames">
<PropertyRef Name="ResourceId" />
</Dependent>
</ReferentialConstraint>
</Association>
<Association Name="FK_Users_Locations">
<End Role="Locations" Type="XDbModel.Store.Locations" Multiplicity="0..1">
<OnDelete Action="Cascade" />
</End>
<End Role="Users" Type="XDbModel.Store.Users" Multiplicity="*" />
<ReferentialConstraint>
<Principal Role="Locations">
<PropertyRef Name="LocationId" />
</Principal>
<Dependent Role="Users">
<PropertyRef Name="LocationId" />
</Dependent>
</ReferentialConstraint>
</Association>
<Association Name="FK_Votes_Posts">
<End Role="Posts" Type="XDbModel.Store.Posts" Multiplicity="1">
<OnDelete Action="Cascade" />
</End>
<End Role="Votes" Type="XDbModel.Store.Votes" Multiplicity="*" />
<ReferentialConstraint>
<Principal Role="Posts">
<PropertyRef Name="PostId" />
</Principal>
<Dependent Role="Votes">
<PropertyRef Name="PostId" />
</Dependent>
</ReferentialConstraint>
</Association>
</Schema>
</edmx:StorageModels>
<!-- CSDL content -->
<edmx:ConceptualModels>
<Schema Namespace="XDbModel" Alias="Self" xmlns:annotation="http://schemas.microsoft.com/ado/2009/02/edm/annotation" xmlns="http://schemas.microsoft.com/ado/2008/09/edm">
<EntityContainer Name="XDbEntities" annotation:LazyLoadingEnabled="true">
<EntitySet Name="Bundles" EntityType="XDbModel.Bundle" />
<EntitySet Name="CellProviders" EntityType="XDbModel.CellProvider" />
<EntitySet Name="Comments" EntityType="XDbModel.Comment" />
<EntitySet Name="LocationPoints" EntityType="XDbModel.LocationPoint" />
<EntitySet Name="Locations" EntityType="XDbModel.Location" />
<EntitySet Name="Offers" EntityType="XDbModel.Offer" />
<EntitySet Name="PostMedias" EntityType="XDbModel.PostMedia" />
<EntitySet Name="Posts" EntityType="XDbModel.Post" />
<EntitySet Name="ResourceEdges" EntityType="XDbModel.ResourceEdge" />
<EntitySet Name="ResourceNames" EntityType="XDbModel.ResourceName" />
<EntitySet Name="Resources" EntityType="XDbModel.Resource" />
<EntitySet Name="sysdiagrams" EntityType="XDbModel.sysdiagram" />
<EntitySet Name="Users" EntityType="XDbModel.User" />
<EntitySet Name="Votes" EntityType="XDbModel.Vote" />
<AssociationSet Name="FK_Comments_Offers" Association="XDbModel.FK_Comments_Offers">
<End Role="Offers" EntitySet="Offers" />
<End Role="Comments" EntitySet="Comments" />
</AssociationSet>
<AssociationSet Name="FK_Comments_Users" Association="XDbModel.FK_Comments_Users">
<End Role="Users" EntitySet="Users" />
<End Role="Comments" EntitySet="Comments" />
</AssociationSet>
<AssociationSet Name="FK_LocationPoints_Locations" Association="XDbModel.FK_LocationPoints_Locations">
<End Role="Locations" EntitySet="Locations" />
<End Role="LocationPoints" EntitySet="LocationPoints" />
</AssociationSet>
<AssociationSet Name="FK_Posts_Locations" Association="XDbModel.FK_Posts_Locations">
<End Role="Locations" EntitySet="Locations" />
<End Role="Posts" EntitySet="Posts" />
</AssociationSet>
<AssociationSet Name="FK_Users_Locations" Association="XDbModel.FK_Users_Locations">
<End Role="Locations" EntitySet="Locations" />
<End Role="Users" EntitySet="Users" />
</AssociationSet>
<AssociationSet Name="FK_Posts_ResourceNames" Association="XDbModel.FK_Posts_ResourceNames">
<End Role="ResourceNames" EntitySet="ResourceNames" />
<End Role="Posts" EntitySet="Posts" />
</AssociationSet>
<AssociationSet Name="FK_Posts_Users" Association="XDbModel.FK_Posts_Users">
<End Role="Users" EntitySet="Users" />
<End Role="Posts" EntitySet="Posts" />
</AssociationSet>
<AssociationSet Name="FK_Votes_Posts" Association="XDbModel.FK_Votes_Posts">
<End Role="Posts" EntitySet="Posts" />
<End Role="Votes" EntitySet="Votes" />
</AssociationSet>
<AssociationSet Name="FK_ResourceEdges_Resources" Association="XDbModel.FK_ResourceEdges_Resources">
<End Role="Resources" EntitySet="Resources" />
<End Role="ResourceEdges" EntitySet="ResourceEdges" />
</AssociationSet>
<AssociationSet Name="FK_ResourceEdges_Resources1" Association="XDbModel.FK_ResourceEdges_Resources1">
<End Role="Resources" EntitySet="Resources" />
<End Role="ResourceEdges" EntitySet="ResourceEdges" />
</AssociationSet>
<AssociationSet Name="FK_ResourceNames_Resources" Association="XDbModel.FK_ResourceNames_Resources">
<End Role="Resources" EntitySet="Resources" />
<End Role="ResourceNames" EntitySet="ResourceNames" />
</AssociationSet>
<AssociationSet Name="PostBundleJunction" Association="XDbModel.PostBundleJunction">
<End Role="Bundles" EntitySet="Bundles" />
<End Role="Posts" EntitySet="Posts" />
</AssociationSet>
</EntityContainer>
<EntityType Name="Bundle">
<Key>
<PropertyRef Name="BundleId" />
</Key>
<Property Name="BundleId" Type="Int32" Nullable="false" />
<NavigationProperty Name="Posts" Relationship="XDbModel.PostBundleJunction" FromRole="Bundles" ToRole="Posts" />
</EntityType>
<EntityType Name="CellProvider">
<Key>
<PropertyRef Name="CellProviderID" />
</Key>
<Property Name="CellProviderID" Type="Guid" Nullable="false" />
</EntityType>
<EntityType Name="Comment">
<Key>
<PropertyRef Name="CommentID" />
答案 0 :(得分：2)
啊，一旦你想到它，它实际上非常简单.. 您正在尝试将其添加到数据上下文中，即使首先从数据库接收到此资源对象。所以错误不是抱怨您的子对象，而是关于您的父对象！ ：）
基本上如果你在SaveResource（）方法中注释第一行它应该可以正常工作！ E.g：
public void SaveResource(Resource resource)
{
// context.AddToResources(resource); //Should also add children.
context.SaveChanges();
}
或者只是将AddChildResource方法移动到DAL：
public void AddChildResource(int parentResourceId, Resource childResource)
{
Resource parentResource = repository.GetResource(parentResourceId);
ResourceEdge inEdge = new ResourceEdge();
inEdge.ToResource = childResource;
parentResource.ToEdges.Add(inEdge);
context.SaveChanges();
}
答案 1 :(得分：0)
据推测，它抱怨childResource没有处于添加状态。您将它添加到处于添加状态的边缘对象。
您可以尝试按照设置该关联的方式进行翻转： -
public void AddChildResource(int parentResourceId, Resource childResource)
{
Resource parentResource = repository.GetResource(parentResourceId);
ResourceEdge inEdge = new ResourceEdge();
// inEdge.ToResource = childResource; <-- don't do this
parentResource.ToEdges.Add(inEdge);
childResource.FromEdges.Add(inEdge); // try this instead
repository.SaveResource(parentResource);
}
答案 2 :(得分：0)
我们已经发布了与您类似的代码recommendation on MSDN。
它有用吗？