oData Web.API中两个EdmEntityType之间的关系

Question

I'm using web.api oData and greate my data model with dynamic with EdmEntityType. I can read the oData-Stream with Excel Power Query, but have to add the relations between the EdmEntityTypes/Tables. I'm now testing with EdmNavigationPropertyInfo, but can't set the info in model in that way, that Power Query could read the relations. Simple example: EdmEntityType Product and ProductGroup Type Product ProductID ProductName FK_ProductGroupID

Type ProductGroup PK_ProductGroupID ProductGroupName

I can read this two types and connect Product/FK_ProductGroupID with ProductGroup/PK_ProductGroupID by hand. Can I create this relationship directly in model? How can I define that die FK-Field und PK-Field are connected?

Best regards Christoph

Answer 1

if you want the referential constraint (foreign key) supported in web api, I create a sample that you can refer to:

EdmModel model = new EdmModel();

EdmEntityType customer = new EdmEntityType("DefaultNamespace", "Customer");
customer.AddKeys(customer.AddStructuralProperty("CustomerId", EdmCoreModel.Instance.GetInt32(false)));
customer.AddStructuralProperty("Name", EdmCoreModel.Instance.GetString(false));
model.AddElement(customer);

EdmEntityType order = new EdmEntityType("DefaultNamespace", "Order");
order.AddKeys(order.AddStructuralProperty("OrderId", EdmCoreModel.Instance.GetInt32(false)));
EdmStructuralProperty orderCustomerId = order.AddStructuralProperty("CustomerForeignKey", EdmCoreModel.Instance.GetInt32(true));
model.AddElement(order);

customer.AddBidirectionalNavigation(
     new EdmNavigationPropertyInfo
     {
         Name = "Orders",
         Target = order,
         TargetMultiplicity = EdmMultiplicity.Many
     },
     new EdmNavigationPropertyInfo
     {
          Name = "Customer",
          TargetMultiplicity = EdmMultiplicity.ZeroOrOne,
          DependentProperties = new[] { orderCustomerId },
     });

Add the routes (V3):

Configuration.Routes.MapODataServiceRoute("odata", "odata", model);

Query the ~/odata/$metadata , you can get the metadata document (OData V3 format) as below:

<?xml version="1.0" encoding="utf-8"?>
<edmx:Edmx Version="1.0" xmlns:edmx="http://schemas.microsoft.com/ado/2007/06/edmx">
  <edmx:DataServices m:DataServiceVersion="3.0" xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata">
    <Schema Namespace="DefaultNamespace" xmlns="http://schemas.microsoft.com/ado/2009/11/edm">
      <EntityType Name="Customer">
        <Key>
          <PropertyRef Name="CustomerId" />
        </Key>
        <Property Name="CustomerId" Type="Edm.Int32" Nullable="false" />
        <Property Name="Name" Type="Edm.String" Nullable="false" />
        <NavigationProperty Name="Orders" Relationship="DefaultNamespace.DefaultNamespace_Order_Customer_DefaultNamespace_Customer_Orders" ToRole="Orders" FromRole="Customer" />
      </EntityType>
      <EntityType Name="Order">
        <Key>
          <PropertyRef Name="OrderId" />
        </Key>
        <Property Name="OrderId" Type="Edm.Int32" Nullable="false" />
        <Property Name="CustomerForeignKey" Type="Edm.Int32" />
        <NavigationProperty Name="Customer" Relationship="DefaultNamespace.DefaultNamespace_Order_Customer_DefaultNamespace_Customer_Orders" ToRole="Customer" FromRole="Orders" />
      </EntityType>
      <Association Name="DefaultNamespace_Order_Customer_DefaultNamespace_Customer_Orders">
        <End Type="DefaultNamespace.Customer" Role="Customer" Multiplicity="0..1" />
        <End Type="DefaultNamespace.Order" Role="Orders" Multiplicity="*" />
        <ReferentialConstraint>
          <Principal Role="Customer">
            <PropertyRef Name="CustomerId" />
          </Principal>
          <Dependent Role="Orders">
            <PropertyRef Name="CustomerForeignKey" />
          </Dependent>
        </ReferentialConstraint>
      </Association>
    </Schema>
  </edmx:DataServices>
</edmx:Edmx>

The referential constraint is presented in metadata document.

Hope it can help you. Thanks.