Dynamic Query with GraphQL, SPQR, and Spring Boot: How to Optimize API Performance

Question

I'm using GraphQL with SPQR and I would like to know if anyone knows how to create a dynamic query using Spring Boot and SPQR.

I have the following query input:

query findAllAlunosSerie {
  findAllAlunosSerie {
    id
    aluno {
      id
      nome
      idade
    }
    serie {
      id
      nome
      tipoSerie {
        id
        nome
      }
    }
  }
}

My goal is to dynamically generate a query based on the user's request, fetching only the requested fields.

Here's my AlunoSerieService class:

@GraphQLApi
@Lazy
@RequiredArgsConstructor(onConstructor = @__(@Autowired))
@Service
@Transactional
public class AlunoSerieService {

    private final AlunoSerieMapper alunoSerieMapper;
    private final AlunoSerieRepository alunoSerieRepository;

    @GraphQLQuery(name = "findAllAlunosSerie")
    @Transactional(readOnly = true)
    public List<AlunoSerieOutput> findAll(@GraphQLEnvironment ResolutionEnvironment environment) {
        return alunoSerieMapper.modelToOutput(alunoSerieRepository.findAll());
    }
}

I would like to know if anyone is familiar with a method that can convert this JSON-like query into a SQL-like structure, enabling me to perform a SELECT query and make it less burdensome for the API. Any suggestions or examples?

Answer 1

To achieve dynamic query generation based on the user's request, you can use the ResolutionEnvironment object provided by SPQR in your GraphQL query resolver. The ResolutionEnvironment object contains information about the requested fields and their selections, which allows you to build the appropriate SQL-like query dynamically.

Here's how you can modify your AlunoSerieService class to achieve dynamic query generation:

@GraphQLApi
@Lazy
@RequiredArgsConstructor(onConstructor = @__(@Autowired))
@Service
@Transactional
public class AlunoSerieService {

    private final AlunoSerieMapper alunoSerieMapper;
    private final AlunoSerieRepository alunoSerieRepository;

    @GraphQLQuery(name = "findAllAlunosSerie")
    @Transactional(readOnly = true)
    public List<AlunoSerieOutput> findAll(@GraphQLEnvironment ResolutionEnvironment environment) {
        DataFetchingFieldSelectionSet selectionSet = environment.dataFetchingFieldSelectionSet();
        List<String> selectedFields = selectionSet.get().keySet().stream()
                .map(GraphQLFieldDefinition::getName)
                .collect(Collectors.toList());

        return alunoSerieMapper.modelToOutput(alunoSerieRepository.findAll(selectedFields));
    }
}

In the updated code, we first obtain the DataFetchingFieldSelectionSet from the ResolutionEnvironment, which represents the selected fields in the GraphQL query. Then, we extract the names of the selected fields and pass them to the alunoSerieRepository.findAll(selectedFields) method.

In your AlunoSerieRepository, you need to implement the findAll method that takes the list of selected fields and constructs the SQL query accordingly. The exact implementation will depend on your data access layer (e.g., JPA, Spring Data, JDBC, etc.). The goal is to dynamically include only the selected fields in the SQL query, making it less burdensome for the API.

Keep in mind that building a full SQL-like query generator can be complex, and you might want to consider using existing libraries or frameworks for query generation to avoid security and performance risks. Additionally, you should implement proper input validation and security checks to prevent any potential misuse or vulnerabilities.