Entity framework 实体框架-继承设计

使用.Net 4和EF 1.0：我有一个每类型的表继承数据库结构和edmx（参见本文末尾的图表和edmx。edmx是通过代码生成器创建的）。我刚刚为这篇文章加入了一个子类型，但是有很多

我们所有的实体框架查询也是动态生成的。因此，当我试图检索产品（可能是书也可能不是书）时，我会生成以下ESQL查询

SELECT VALUE [tb_product] FROM [tb_product] as [tb_product] WHERE (([tb_product].[Id] = @p0))

如果我请求的对象是一本书，则返回给我的对象类型为“tb_product”。我似乎无法从该tb_产品对象强制转换或访问“book”信息

如何修改查询、edmx或其他组件，以便在查询基本类型时，也可以访问所有相关子类型信息，而无需再次访问数据库。我可以吗

  <edmx:Runtime>
<!-- SSDL content -->
<edmx:StorageModels>
  <Schema Namespace="MyModel.Store" Alias="Self" Provider="System.Data.SqlClient" ProviderManifestToken="2005" xmlns:store="http://schemas.microsoft.com/ado/2007/12/edm/EntityStoreSchemaGenerator" xmlns="http://schemas.microsoft.com/ado/2006/04/edm/ssdl">
    <EntityContainer Name="MyModelStoreContainer">       
      <EntitySet Name="tb_productBook" EntityType="MyModel.Store.tb_productBook" store:Type="Tables" Schema="dbo" />      
      <EntitySet Name="tb_product" EntityType="MyModel.Store.tb_product" store:Type="Tables" Schema="dbo" />               
      <AssociationSet Name="FK_IdProductBook_Product" Association="MyModel.Store.FK_IdProductBook_Product">
        <End Role="tb_product" EntitySet="tb_product" />
        <End Role="tb_productBook" EntitySet="tb_productBook" />
      </AssociationSet>        
    </EntityContainer>   
    <EntityType Name="tb_productBook">
      <Key>
        <PropertyRef Name="id" />
      </Key>
      <Property Name="id" Type="int" Nullable="false" />
      <Property Name="title" Type="varchar" Nullable="false" MaxLength="150" />
      <Property Name="subtitle" Type="varchar" Nullable="false" MaxLength="150" />
      <Property Name="length" Type="int" Nullable="false" />
      <Property Name="productCoverTypeId" Type="int" Nullable="false" />
      <Property Name="volumeEdition" Type="varchar" Nullable="false" MaxLength="15" />
      <Property Name="publisherName" Type="varchar" Nullable="false" MaxLength="100" />
      <Property Name="publishDate" Type="datetime" />
      <Property Name="iSBNNumber" Type="varchar" Nullable="false" MaxLength="30" />
      <Property Name="description" Type="varchar" Nullable="false" />
      <Property Name="authorBio" Type="varchar" Nullable="false" />
      <Property Name="audience" Type="varchar" Nullable="false" />
      <Property Name="expireDate" Type="datetime" />
      <Property Name="vendorId" Type="int" Nullable="false" />
      <Property Name="productCommissionTypeId" Type="int" Nullable="false" />
      <Property Name="commissionValue" Type="decimal" Nullable="false" Precision="9" Scale="2" />
      <Property Name="languageId" Type="int" Nullable="false" />
      <Property Name="countryId" Type="int" Nullable="false" />
      <Property Name="stateId" Type="int" Nullable="false" />
      <Property Name="inventoryLocation" Type="varchar" Nullable="false" MaxLength="2000" />
    </EntityType>     
    <EntityType Name="tb_product">
      <Key>
        <PropertyRef Name="id" />
      </Key>
      <Property Name="id" Type="int" Nullable="false" StoreGeneratedPattern="Identity" />
      <Property Name="name" Type="varchar" MaxLength="100" />
      <Property Name="productSku" Type="varchar" Nullable="false" MaxLength="17" />
      <Property Name="productTypeId" Type="int" Nullable="false" />
      <Property Name="price" Type="decimal" Nullable="false" Precision="9" Scale="2" />
      <Property Name="marketOnWeb" Type="bit" Nullable="false" />
      <Property Name="subsidiaryId" Type="int" Nullable="false" />
      <Property Name="lmsProductId" Type="int" />
      <Property Name="topicId" Type="int" />
      <Property Name="categoryId" Type="int" />
      <Property Name="eventId" Type="int" />
      <Property Name="note" Type="varchar" />
      <Property Name="expirationDate" Type="datetime" />
      <Property Name="mediaLength" Type="int" />
      <Property Name="urlSlug" Type="varchar" MaxLength="200" />
      <Property Name="productSourceId" Type="int" />
      <Property Name="created" Type="datetime" Nullable="false" />
      <Property Name="createdBy" Type="varchar" Nullable="false" MaxLength="30" />
      <Property Name="lastUpdated" Type="datetime" Nullable="false" />
      <Property Name="lastUpdatedBy" Type="varchar" Nullable="false" MaxLength="30" />
    </EntityType>        
    <Association Name="FK_IdProductBook_Product">
      <End Role="tb_product" Type="MyModel.Store.tb_product" Multiplicity="1">
        <OnDelete Action="Cascade" />
      </End>
      <End Role="tb_productBook" Type="MyModel.Store.tb_productBook" Multiplicity="0..1" />
      <ReferentialConstraint>
        <Principal Role="tb_product">
          <PropertyRef Name="id" />
        </Principal>
        <Dependent Role="tb_productBook">
          <PropertyRef Name="id" />
        </Dependent>
      </ReferentialConstraint>
    </Association>
  </Schema>
</edmx:StorageModels>
<!-- CSDL content -->
<edmx:ConceptualModels>
  <Schema Namespace="MyModel" Alias="Self" xmlns="http://schemas.microsoft.com/ado/2006/04/edm">
    <EntityContainer Name="MyEntities">
      <EntitySet Name="tb_product" EntityType="MyModel.tb_product" />                 
    </EntityContainer>        
    <EntityType Name="tb_productBook" BaseType="MyModel.tb_product">
      <Property Name="title" Type="String" Nullable="false" />
      <Property Name="subtitle" Type="String" Nullable="false" />
      <Property Name="length" Type="Int32" Nullable="false" />
      <Property Name="volumeEdition" Type="String" Nullable="false" />
      <Property Name="publisherName" Type="String" Nullable="false" />
      <Property Name="publishDate" Type="DateTime" Nullable="true" />
      <Property Name="iSBNNumber" Type="String" Nullable="false" />
      <Property Name="description" Type="String" Nullable="false" />
      <Property Name="authorBio" Type="String" Nullable="false" />
      <Property Name="audience" Type="String" Nullable="false" />
      <Property Name="expireDate" Type="DateTime" Nullable="true" />
      <Property Name="vendorId" Type="Int32" Nullable="false" />
      <Property Name="commissionValue" Type="Decimal" Nullable="false" />
      <Property Name="inventoryLocation" Type="String" Nullable="false" />
      <NavigationProperty Name="ProductBook_Country" Relationship="MyModel.FK_CountryProductBook_Country" FromRole="tb_productBook" ToRole="tb_country" />
      <NavigationProperty Name="ProductBook_Language" Relationship="MyModel.FK_LanguageProductBook_Language" FromRole="tb_productBook" ToRole="tb_language" />
      <NavigationProperty Name="ProductBook_ProductCommissionType" Relationship="MyModel.FK_ProductCommissionTypeProductBook_ProductCommissionType" FromRole="tb_productBook" ToRole="tb_productCommissionType" />
      <NavigationProperty Name="ProductBook_ProductCoverType" Relationship="MyModel.FK_ProductCoverTypeProductBook_ProductCoverType" FromRole="tb_productBook" ToRole="tb_productCoverType" />
      <NavigationProperty Name="ProductBook_State" Relationship="MyModel.FK_StateProductBook_State" FromRole="tb_productBook" ToRole="tb_state" />
    </EntityType>    
    <EntityType Name="tb_product">
      <Key>
        <PropertyRef Name="id" />
      </Key>
      <Property Name="id" Type="Int32" Nullable="false" />
      <Property Name="name" Type="String" Nullable="true" />
      <Property Name="productSku" Type="String" Nullable="false" />
      <Property Name="price" Type="Decimal" Nullable="false" />
      <Property Name="marketOnWeb" Type="Boolean" Nullable="false" />
      <Property Name="subsidiaryId" Type="Int32" Nullable="false" />
      <Property Name="lmsProductId" Type="Int32" Nullable="true" />
      <Property Name="topicId" Type="Int32" Nullable="true" />
      <Property Name="note" Type="String" Nullable="true" />
      <Property Name="expirationDate" Type="DateTime" Nullable="true" />
      <Property Name="mediaLength" Type="Int32" Nullable="true" />
      <Property Name="urlSlug" Type="String" Nullable="true" />
      <Property Name="created" Type="DateTime" Nullable="false" />
      <Property Name="createdBy" Type="String" Nullable="false" />
      <Property Name="lastUpdated" Type="DateTime" Nullable="false" />
      <Property Name="lastUpdatedBy" Type="String" Nullable="false" />
      <NavigationProperty Name="CampaignAdvertisedProduct_Product" Relationship="MyModel.FK_ProductCampaignAdvertisedProduct_Product" FromRole="tb_product" ToRole="tb_campaignAdvertisedProduct" />
      <NavigationProperty Name="DiscountGroupProduct_Product" Relationship="MyModel.FK_ProductDiscountGroupProduct_Product" FromRole="tb_product" ToRole="tb_discountGroupProduct" />
      <NavigationProperty Name="LogCampaignResponseUpdate_Product" Relationship="MyModel.FK_ProductLogCampaignResponseUpdate_Product" FromRole="tb_product" ToRole="tb_logCampaignResponseUpdate" />
      <NavigationProperty Name="ProductAuthor_Product" Relationship="MyModel.FK_ProductProductAuthor_Product" FromRole="tb_product" ToRole="tb_productAuthor" />
      <NavigationProperty Name="ProductImage_Product" Relationship="MyModel.FK_ProductProductImage_Product" FromRole="tb_product" ToRole="tb_productImage" />
      <NavigationProperty Name="ProductMarketingContent_Product" Relationship="MyModel.FK_ProductProductMarketingContent_Product" FromRole="tb_product" ToRole="tb_productMarketingContent" />
      <NavigationProperty Name="ProductOnsiteStaffAgency_Product" Relationship="MyModel.FK_ProductProductOnsiteStaffAgency_Product" FromRole="tb_product" ToRole="tb_productOnsiteStaffAgency" />
      <NavigationProperty Name="ProductProblem_Product" Relationship="MyModel.FK_ProductProductProblem_Product" FromRole="tb_product" ToRole="tb_productProblem" />
      <NavigationProperty Name="ProductVenue_Product" Relationship="MyModel.FK_ProductProductVenue_Product" FromRole="tb_product" ToRole="tb_productVenue" />
      <NavigationProperty Name="VenueEmailRequest_Product" Relationship="MyModel.FK_ProductVenueEmailRequest_Product" FromRole="tb_product" ToRole="tb_venueEmailRequest" />
      <NavigationProperty Name="Product_Category" Relationship="MyModel.FK_CategoryProduct_Category" FromRole="tb_product" ToRole="tb_category" />
      <NavigationProperty Name="Product_ProductSource" Relationship="MyModel.FK_ProductSourceProduct_ProductSource" FromRole="tb_product" ToRole="tb_productSource" />
      <NavigationProperty Name="Product_ProductType" Relationship="MyModel.FK_ProductTypeProduct_ProductType" FromRole="tb_product" ToRole="tb_productType" />
      <NavigationProperty Name="Product_Event" Relationship="MyModel.FK_EventProduct_Event" FromRole="tb_product" ToRole="tb_event" />
      <NavigationProperty Name="tb_category" Relationship="MyModel.tb_product_category" FromRole="tb_product" ToRole="tb_category" />
      <NavigationProperty Name="tb_contact" Relationship="MyModel.tb_product_faculty" FromRole="tb_product" ToRole="tb_contact" />
      <NavigationProperty Name="tb_state" Relationship="MyModel.tb_product_State" FromRole="tb_product" ToRole="tb_state" />
      <NavigationProperty Name="tb_vendorCost" Relationship="MyModel.tb_product_VendorCost" FromRole="tb_product" ToRole="tb_vendorCost" />
      <NavigationProperty Name="tb_vendorInvoice" Relationship="MyModel.tb_product_VendorInvoice" FromRole="tb_product" ToRole="tb_vendorInvoice" />
      <NavigationProperty Name="tb_vendorPayment" Relationship="MyModel.tb_product_VendorPayment" FromRole="tb_product" ToRole="tb_vendorPayment" />
    </EntityType>     
  </Schema>
</edmx:ConceptualModels>
<!-- C-S mapping content -->
<edmx:Mappings>
  <Mapping Space="C-S" xmlns="urn:schemas-microsoft-com:windows:storage:mapping:CS">
    <EntityContainerMapping StorageEntityContainer="MyModelStoreContainer" CdmEntityContainer="MyEntities">      
      <EntitySetMapping Name="tb_product">
        <EntityTypeMapping TypeName="IsTypeOf(MyModel.tb_product)">
          <MappingFragment StoreEntitySet="tb_product">
            <ScalarProperty Name="lastUpdatedBy" ColumnName="lastUpdatedBy" />
            <ScalarProperty Name="lastUpdated" ColumnName="lastUpdated" />
            <ScalarProperty Name="createdBy" ColumnName="createdBy" />
            <ScalarProperty Name="created" ColumnName="created" />
            <ScalarProperty Name="urlSlug" ColumnName="urlSlug" />
            <ScalarProperty Name="mediaLength" ColumnName="mediaLength" />
            <ScalarProperty Name="expirationDate" ColumnName="expirationDate" />
            <ScalarProperty Name="note" ColumnName="note" />
            <ScalarProperty Name="topicId" ColumnName="topicId" />
            <ScalarProperty Name="lmsProductId" ColumnName="lmsProductId" />
            <ScalarProperty Name="subsidiaryId" ColumnName="subsidiaryId" />
            <ScalarProperty Name="marketOnWeb" ColumnName="marketOnWeb" />
            <ScalarProperty Name="price" ColumnName="price" />
            <ScalarProperty Name="productSku" ColumnName="productSku" />
            <ScalarProperty Name="name" ColumnName="name" />
            <ScalarProperty Name="id" ColumnName="id" />
          </MappingFragment>
        </EntityTypeMapping>          
        <EntityTypeMapping TypeName="IsTypeOf(MyModel.tb_productBook)">
          <MappingFragment StoreEntitySet="tb_productBook">
            <ScalarProperty Name="inventoryLocation" ColumnName="inventoryLocation" />
            <ScalarProperty Name="commissionValue" ColumnName="commissionValue" />
            <ScalarProperty Name="vendorId" ColumnName="vendorId" />
            <ScalarProperty Name="expireDate" ColumnName="expireDate" />
            <ScalarProperty Name="audience" ColumnName="audience" />
            <ScalarProperty Name="authorBio" ColumnName="authorBio" />
            <ScalarProperty Name="description" ColumnName="description" />
            <ScalarProperty Name="iSBNNumber" ColumnName="iSBNNumber" />
            <ScalarProperty Name="publishDate" ColumnName="publishDate" />
            <ScalarProperty Name="publisherName" ColumnName="publisherName" />
            <ScalarProperty Name="volumeEdition" ColumnName="volumeEdition" />
            <ScalarProperty Name="length" ColumnName="length" />
            <ScalarProperty Name="subtitle" ColumnName="subtitle" />
            <ScalarProperty Name="title" ColumnName="title" />
            <ScalarProperty Name="id" ColumnName="id" />
          </MappingFragment>
        </EntityTypeMapping>            
      </EntitySetMapping>
    </EntityContainerMapping>
  </Mapping>
</edmx:Mappings>

---

您能否尝试在实体SQL查询中使用

of type

（）for

ProductBook

，看看它是否返回预期的

ProductBook

实体？阅读文档我认为这不是我想要的。我需要能够得到所有产品，无论其子类型。但是，一旦我拥有了对象集合，我还希望能够查看每个单独的对象，并获得适当的子类型信息（当它们有了子类型信息时，一些产品将只属于基类类型）。我理解这一点。我的建议旨在测试派生实体是否被加载。如果您有一个正确的TPT映射，那么您的查询实际上应该按您所希望的那样工作，即当数据库中有一个

ProductBook

时，它应该具体化

ProductBook

实例。对我来说，EDMX看起来没有明显的错误，但我不确定。顺便说一句，如果生成的查询看起来正确，您是否签入了sql探查器？它应该包含

Product

和

ProductBook

（以及其他派生）表之间的连接。我不敢相信我没有想到这一点-我们确实有生成的实际SQL的日志。明天早上我会去看看。啊，我真是个傻瓜——检查原始SQL确认查询正在检索所需的所有数据。我想我只是想把错误的目标投射到这本书上。当我纠正这一点时，我得到了我预期的结果。谢谢你的时间和耐心！