Exposing link on collection entity in spring data REST - spring-data

Question

Using spring data REST I have exposed a ProjectRepository that supports listing projects and performing CRUD operations on them. When I go to http://localhost:8080/projects/ I get the list of projects as I expect.
What I am trying to do is add a custom action to the _links section of the JSON response for the Project Collection.
For example, I'd like the call to http://localhost:8080/projects/ to return something like this:
{
"_links" : {
"self" : {
"href" : "http://localhost:8080/projects/{?page,size,sort}",
"templated" : true
},
"search" : {
"href" : "http://localhost:8080/projects/search"
},
"customAction" : {
"href" : "http://localhost:8080/projects/customAction"
}
},
"page" : {
"size" : 20,
"totalElements" : 0,
"totalPages" : 0,
"number" : 0
}
}
Where customAction is defined in some controller.
I've tried creating the following class:
public class ProjectCollectionResourceProcessor implements ResourceProcessor<Resource<Collection<Project>>> {
#Override
public Resource<Collection<Project>> process(Resource<Collection<Project>> listResource) {
// code to add the links to customAction here
return listResource;
}
}
and adding adding the following Bean to my applications configuration:
#Bean
public ProjectCollectionResourceProcessor projectCollectionResourceProcessor() {
return new ProjectCollectionResourceProcessor();
}
But process(...) doesn't ever seem to get called. What is the correct way to add links to Collections of resources?

Answer 1

The collection resources render an instance of Resources<Resource<Project>>, not Resource<Collection<Project>>. So if you change the generic typing in your ResourceProcessor implementation accordingly that should work as you expect it.

Answer 2

I had the same issue. What worked for me was:
public class ProjectsResourceProcessor implements ResourceProcessor<PagedResources<Resource<Project>>> {
private final #NonNull EntityLinks entityLinks;
#Override
public PagedResources<Resource<Project>> process(PagedResources<Resource<Project>> pagedResources) {
...
return pagedResources;
}
}