[CAUSEWAY-3752] Provide SPI to describe which classes are surfaced by the different viewers.

• Type: New Feature
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.0.0
• Fix Version/s: 3.3.0, 2.3.0
• Component/s: Core, Viewer GraphQL, Viewer RO, Viewer Wicket
• Assignee: Daniel Keir Haywood
• Reporter: Daniel Keir Haywood
• Created: 29/May/24 11:22
• Updated: 28/Sep/24 11:52

Description

Before releasing 2.0.0/3.0.0, we decided to make `@DomainService(nature=VIEW|REST_ONLY)` a no-op , for a couple of reasons:

• we now have a GraphQL viewer, and the enum didn't seem general enough
• the REST API has its own rather adhoc mechanism for what to expose: public, prototyping or private
  • but this only affects the Swagger file, not the actual API that's actually available
• the GraphQL viewer has an issue that it takes a loooong time to expose the entire API; and probably we wouldn't want to do that.

 
In removing `@DomainService(nature=...)`, we told ourselves that users could just use security; but that doesn't address the above issues.
 
The proposal is to introduce this SPI:
 

enum ViewerType {
  WICKET,
  REST,
  GRAPHQL
}
public interface ViewerFilterSpi {
    /**
     * the classes to be 
     */
    Optional<List<Class<?>>> include(ViewerType);
 
    Optional<List<Class<?>>> exclude(ViewerType);
} 

 
This will be used by the different viewers at different stages:

• by Wicket viewer - when rendering
• by REST API - when generating swagger + to prevent calls to anything that's not specified...
• by GraphQL - when building the GraphQL metamodel

 

public class MyAppViewFilter implements ... {
 public Optional<List<Class<?>>> include(...) {
   switch viewerType {
     case WICKET:
       return Optional.empty;
     case REST:
       return Optional.of(Arrays.asList(....));
     case GRAPHQL:
       return Optional.of(Arrays.asList(....));
    }
  }
  public Optional<List<Class>>> exclude(...) {
    switch viewerType {
      case WICKET:
        return include(REST);
      case REST:
        return Optional.empty();
      case GRAPHQL:
        return Optional.empty();
    }
  }
}