How to return representations of associations in a Spring Data REST resource?

Question

There are following URLS - /users/2/profile , /users/2/userPosts

I need to concat output of both Spring Data REST results in server side and build single JSON from them and send on different URL /users/2/custom .

So, I am thinking to make 2 calls to SDR urls from Spring MVC, can we do this using RestTemplate and some JSON concat utility , here server and database is on same machine so RestTemplate will probably have localhost

An example will help

Answer 1

You might rather want to look into the projections feature of Spring Data REST which allows you to craft custom responses by using interfaces as described in this blog post .

As both properties ( profile and userPosts ) seem to be associations of a user item resource it should be sufficient to do something like this:

@Projection(types = User.class)
interface UserWithDetails {

  // List getters for basic properties you want to expose…

  // Add dedicated getters for associations to be included

  Profile getProfile();

  List<Post> getUserPosts();
}

Clients can now pass a projection parameter to the resources exposed to see the expanded representation.

As an alternative, you can create these kinds of interfaces for Profile and Post and configure @RepositoryRestResource on the repositories for both of these types to contain excerptProjection = YourProjectionInterface.class . This will cause the projections to be rendered whenever an association is included in the response (ie an actually-linked-to-resource could be embedded).