Multi-Table APIs
TL;DR - use Swagger to configure API
Multi-Table APIs can be configured using the include argument in the API call, and tested in Swagger.
Best Practices
Swagger
Provider-defined APIs are configured by the API caller - the client application. It's usually best to test these before testing your client app by using the created Swagger. Note it provides the ability to copy the URL to paste into your app.
You may find it helpful to copy the json response to a json formatter, such as jsonformatter or jsongrid.
Disable Security
It also makes things simpler if you temporarily disable security (unless that's what you are testing!). Created projects include Run Configurations for this.
Use include for related data
The include argument enables you to specify what related data is returned. For example, in the sample northwind database, you can obtain a Customer, their Orders, the OrderDetails, and the Product Data like this:
curl -X GET "http://localhost:5656/api/Customer/ALFKI/?\
include=OrderList%2COrderList.OrderDetailList%2COrderList.OrderDetailList.Product&\
fields%5BCustomer%5D=Id%2CCompanyName%2CContactName%2CContactTitle%2CAddress%2CCity%2CRegion%2CPostalCode%2CCountry%2CPhone%2CFax%2CBalance%2CCreditLimit%2COrderCount%2CUnpaidOrderCount%2CClient_id" \
-H 'accept: application/vnd.api+json' \
-H 'Content-Type: application/vnd.api+json'
Note the include argument, repeated here with commas:
These terms are the Parent / Child Relationship names, from your data model. Note they support multi-level navigations, such as OrderList.OrderDetailList. For more on relationship names, click here.
To explore the resultant json, click here.