My relationship between the parent and child is that they are connected by an edge. It is similiar to a directed graph structure.
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;
}
Service:
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);
}
Error: An object with the same key already exists in the ObjectStateManager. The existing object is in the Unchanged state. An object can only be added to the ObjectStateManager again if it is in the added state.
Image:
I have been told this is the sequence in submitting a child to an already existing parent:
Get parent -> Attach Child to parent -> submit parent.
That is the sequence I used. The code above is extracted from an ASP.NET MVC 2 application using the repository pattern.
EDMX file:
<?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" />
Ah, it’s actually very simple, once you think about it..
What you’re trying to do it add the resource to the data context, even though this resource object was received from the database in the first place. So the error is not complaining about your child objects, but about your parent object! 🙂
Basically if you comment the first line in the SaveResource() method it should just work fine!
E.g.:
Or just move the AddChildResource method to your DAL: