Any well known java library to return only requested fields for REST API

Question

Looking for a reputed java library for Spring boot application, where, GET api which returns a list of resources quite huge in size. To reduce the size of the response, one of the conventions is to only have fields requested in response.

Example,

GET /v1/users/

{
   "data" : 
   {
     [
        {
            "name" : "User1",
            "phone" : "800-999-9999",
            "city" : "XYZ1",
            "country" : "PQR1"
        },
        {
            "name" : "User2",
            "phone" : "800-999-9999",
            "city" : "XYZ2",
            "country" : "PQR2"
         }
     ]
   }
}

For lighter version of response, when fields are passed as query parameters

GET /v1/users/?fields=name,city

{
   "data" : 
   {
     [
        {
            "name" : "User1",
            "city" : "XYZ1"
        },
        {
            "name" : "User2",
            "city" : "XYZ2"
         }
     ]
   }
}

To learn more "Teach a dog to REST". Mentions some the practices at linkedIn, facebook, twilio, etc.

I came across "https://github.com/monitorjbl/json-view". But was shot down by the team.

Does anyone know a open-source licensed project to this? How do organizations using java spring microservices implement this feature? Thanks!

score 1 · Answer 1 · answered Nov 07 '19 at 20:16

This is one of the difficult things with API design. You need to find the right trade-off between making it generic enough to support several use-cases without adding information which is rarely needed. One possibility is to create another endpoint. However, this can lead to lots of endpoints and bad API design.

I don't exactly know your use-case, but instead of REST, you can look into GraphQL. In GraphQL, the client basically tells the server what information it wants to receive.

Besides that, there are already a few posts on stackoverflow which may help:

score 0 · Answer 2 · answered Nov 07 '19 at 20:42

One approach that might work (haven't tried this) would be to use e.g. flexjson, and specify the fields to include in the response when calling JSONSerializer.serialize(), something like:

@RequestMapping(value = "/v1/users", method = GET)
@ResponseBody
public String getUserDataReturningOnlyRequestedFields(
  @RequestParam(List<String> fields) {
  ... obtain user data DTO containing entire response ...
  ... create comma-delimited string from fields list ...
  return new JSONSerializer().include(comma-delimited fields).serialize(dto);
}

Any well known java library to return only requested fields for REST API

2 Answers2