13.3 Multiple Navigation property binding path

Since Web API OData V6.0.0 beta, It supports to configure multiple navigation property binding paths.

Original navigation property binding

The following APIs are used to add navigation property binding in model builder.

1. HasManyBinding()
2. HasRequiredBinding()
3. HasOptionalBinding()

So, we can do as:

public class Customer
{
  public int Id { get; set; }
  
  public Order SingleOrder {get;set;}  // single navigation property
  
  public IList<Order> Orders {get;set;} // collection navigation property
}

public class Order
{
  public int Id { get; set; }
}

ODataModelBuilder builder = new ODataModelBuilder();
var customers = builder.EntitySet<Cusomter>("Customers");
customers.HasManyBinding(c => c.Orders, "Orders");
customers.HasRequiredBinding(c => c.SingleOrder, "SingleOrders");

We can get the following result:

<EntityContainer Name="Container">
  <EntitySet Name="Customers" EntityType="System.Web.OData.Builder.Cusomter">
    <NavigationPropertyBinding Path="Orders" Target="Orders" />
    <NavigationPropertyBinding Path="SingleOrder" Target="SingleOrders" />
  </EntitySet>
  <EntitySet Name="Orders" EntityType="System.Web.OData.Builder.Order" />
  <EntitySet Name="SingleOrders" EntityType="System.Web.OData.Builder.Order" />
</EntityContainer>

Where, the binding path is straight-forward, just as the navigation property name. Before 6.0.0, it doesn’t support to:

1. Add the complex property into binding path
2. Add the type cast into binding path

Multiple navigation property binding path in model builder

In Web API OData V6.0.0 beta, we add a new generic type class to configure the multiple binding path:

BindingPathConfiguration{TStructuralType}

In this class, it provides the following APIs to add binding path:

1. HasManyPath()
2. HasSinglePath()

It also provides the following APIs to bind the navigation property with multiple binding path to a targe navigation source.

1. HasManyBinding()
2. HasRequiredBinding()
3. HasOptionalBinding()

So, the normal navigation property binding configuration flow is：

1. Call Binding from NavigationSourceConfiguration{TEntityType} to get an instance of BindingPathConfiguration{TEntityType}
2. Call HasManyPath()/HasSinglePath from BindingPathConfiguration{TEntityType}` to add a binding path
3. Repeat step-2 if necessary
4. Call HasManyBinding()/HasRequiredBinding()/HasOptionalBinding() to add the target navigation source.

Here’s an example:

builder.EntitySet<Customer>("Customers")
   .Binding
   .HasManyPath(c => c.Locations)
   .HasSinglePath(a => a.LocationInfo)
   .HasRequiredBinding(c => c.City, "Cities");
   

Example

Let’s have the following CLR classes as the model:

Entity types

public class Cusomter
{
  public int Id { get; set; }

  public Animal Pet { get; set; }
}

public class VipCustomer : Cusomter
{
  public List<Address> VipLocations { get; set; }
}

public class City
{
  public int Id { get; set; }
}

Complex types

public class Animal
{
}

public class Human : Animal
{
    public UsAddress HumanAddress { get; set; }
}

public class Horse : Animal
{
    public UsAddress HorseAddress { get; set; }
    public IList<UsAddress> HorseAddresses { get; set; }
}
public class Address
{
  public City City { get; set; }
}

public class UsAddress : Address
{
  public City SubCity { get; set; }
}

Add navigation property binding:

customers.HasManyPath((VipCustomer v) => v.VipLocations).HasRequiredBinding(a => a.City, "A");
customers.HasManyPath((VipCustomer v) => v.VipLocations).HasRequiredBinding((UsAddress a) => a.SubCity, "B");

var pet = customers.HasRequiredPath(c => c.Pet);

pet.HasRequiredPath((Human p) => p.HumanAddress)
    .HasRequiredBinding(c => c.SubCity, "HumanCities");

pet.HasRequiredPath((Horse h) => h.HorseAddress).HasRequiredBinding(c => c.SubCity, "HorseCities");

pet.HasManyPath((Horse h) => h.HorseAddresses).HasRequiredBinding(c => c.SubCity, "HorseCities");
  

So, we can get the following target binding:

<Schema Namespace="Default" xmlns="http://docs.oasis-open.org/odata/ns/edm">
  <EntityContainer Name="Container">
    <EntitySet Name="Customers" EntityType="System.Web.OData.Builder.Cusomter">
      <NavigationPropertyBinding Path="Pet/System.Web.OData.Builder.Human/HumanAddress/SubCity" Target="HumanCities" />
      <NavigationPropertyBinding Path="Pet/System.Web.OData.Builder.Horse/HorseAddress/SubCity" Target="HorseCities" />
      <NavigationPropertyBinding Path="Pet/System.Web.OData.Builder.Horse/HorseAddresses/SubCity" Target="HorseCities" />
      <NavigationPropertyBinding Path="System.Web.OData.Builder.VipCustomer/VipLocations/System.Web.OData.Builder.UsAddress/SubCity" Target="B" />
      <NavigationPropertyBinding Path="System.Web.OData.Builder.VipCustomer/VipLocations/City" Target="A" />
    </EntitySet>
    <EntitySet Name="A" EntityType="System.Web.OData.Builder.City" />
    <EntitySet Name="B" EntityType="System.Web.OData.Builder.City" />
    <EntitySet Name="HumanCities" EntityType="System.Web.OData.Builder.City" />
    <EntitySet Name="HorseCities" EntityType="System.Web.OData.Builder.City" />
  </EntityContainer>
</Schema>

Where: As example shown:

1. It supports single property with multiple binding path.
2. It supports collection property with mutliple binding path.
3. It also supports mulitple binding path with inheritance type.

Besides, the HasManyPath()/HasSinglePath() has onverload methods to configure the containment binding path.

Multiple navigation property binding path in convention model builder

In convention model builder, it will automatically traverl all property binding paths to add a binding for the navigation proeprty.

There’s an unit test that you can refer to.