How Links Between Object Types Work in Anypoint DataGraph

You can link your current object type to a different target object type to improve the query experience. Linking enables you to join fields from two related types that describe different objects and create a connection between those types.

You can link your current object type to a target object type if your current type is not collaboration enabled; however, the target must be collaboration enabled. See Enabling Object Type Collaboration in Anypoint DataGraph for more information about how collaboration works.

Creating a Link Between Object Types

Consider two API schemas, one with the object type Order and the other with the object type Customer:

Order Schema Customer Schema

Order Schema	Customer Schema
`ordersByOrderId (orderId:String!):Order -------------------- -------------------- Order -------------------- orderId: String! Items: Item[] customerId: String!`	`customersByCustomerId (customerId:String!): Customer -------------------- -------------------- Customer -------------------- customerId: String! name: String!`

ordersByOrderId (orderId:String!):Order
--------------------
--------------------
Order
--------------------
orderId: String!
Items: Item[]
customerId: String!

customersByCustomerId (customerId:String!): Customer
--------------------
--------------------
Customer
--------------------
customerId: String!
name: String!

Your unified schema currently looks like this:

ordersByOrderId (orderId:String!):Order
customersByCustomerId (customerId:String!): Customer
--------------------
--------------------
Order
--------------------
orderId: String!
Items: Item[]
customerId: String!
--------------------
--------------------
Customer
--------------------
customerId: String!
name: String!

In this current configuration, to query the order and the customer datasets at the same time, you must query both types separately:

ordersByOrderId (orderId: “123”) {
  orderId
  customerId
}
customersByCustomerId (customerId: “CC83”) {
  customerId
  name
}

Additionally, to query the customer data for the order, you must know the customer ID associated with it.

However, note that the Order object type has a field that returns customerId. You can link your Order object type to the Customer object type using customerId: String! as a foreign key, pointing to Customer as your target type. Doing so causes your selected foreign key to map to the primary key customerId:String! on the Customer type.

As a result of this link:

A new field called Customer is created in the Order object type that now returns the linked Customer object type.

The new object type generated in your API schema acts as a reference to the type in the Customer API schema, ensuring that any changes made to the Customer API schema do not affect your Order API schema:

ordersByOrderId (orderId:String!):Order
--------------------
--------------------
Order
--------------------
orderId: String!
Items: Item[]
customer: Customer
--------------------
--------------------
Customer
--------------------
--------------------
customerId: String!

In the updated unified schema, you can see that the Order type is linked to Customer type:

ordersByOrderId (orderId:String!):Order
--------------------
--------------------
Order
--------------------
orderId: String!
Items: Item[]
customer: Customer
--------------------
--------------------
Customer
--------------------
--------------------
customerId: String
name: String

After linking, consumers of your unified schema can query the Order dataset along with its related Customer dataset without having to know the associated customerId:

ordersByOrderId (orderId: “123”) {
  orderId
  customer {
    name
  }
}

Creating a Link Between Object Types That Use Composite Keys

The default query method for a type can also use composite keys.

Consider a target type Customer that uses composite keys for its default query method: customerId and customerStatus:

customerDetail (id: string!, status: string!): Customer
--------------------
--------------------
Customer
--------------------
customerDetail: string!, string!
customerId: String!
customerStatus: String!

Assuming the same Order schema from above:

ordersByOrderId (orderId:String!):Order
--------------------
--------------------
Order
--------------------
orderId: String!
Items: Item[]
customerId: String!

If you linked the Customer type as a target for the Order type, the unified schema reflects the link as follows:

ordersByOrderId (orderId:String!):Order
--------------------
--------------------
Order
--------------------
orderId: String!
Items: Item[]
customerId: Customer
customerStatus: Customer
--------------------
--------------------
Customer
--------------------
--------------------
customerDetail: String!, String!
customerId: String!
customerStatus: String!

Additional Resources

Create and Edit Links Between Object Types