Jersey 2.* & HK2. Inject different object (e.g. DAO) based on a path parameter

Question

I am implementing a multi-tenant application. Many of my resources have paths like "/api/tenant/{tenant_id}/resource/path/". What I would like to do is to inject different DAOs (or possibly other objects) to the resource based on the "{tenant_id}" path parameter.

I have two suboptimal ideas on how to achieve something similar:

1. Use a wrapper class like this:

   class SomeDAOWrapper
   {
       SomeDAO getSomeDAO()
       {
           return new SomeDAO(tenantId_m);
           // Alternatively we could store the DAOs in some hash-table
           // with tenantId_m as the key.
       }
   
       @PathParam("tenant_id")
       private long tenantId_m;
   }
   

   Then in my resource class I would have SomeDAOWrapper as an attribute annotated with @BeanParam.

2. Use a sub-resource locator on path "/api/tenant/{tenant_id}" that would return the resources with the correct DAOs.

Any other ideas? Ideally what I would like to do is to simply have SomeDAO attribute in my resource class that is annotated with @Inject or something similar (and that would use some factory that takes the tenant_id path parameter into account).

Answer 1

I ran into this same kind of problem and ended up using the guice multibinder solution. You essentially bind your Dao's to a MultiBinder and then Inject a factory into your service. This was the cleanest solution I could come up with for the problem.

Check out this url, it is pretty much what I did to get dependency injection working with a resource that needed a specific dao.

https://groups.google.com/forum/#!topic/google-guice/J6S77sILTAY