Using GraphQL strictly as a query language

Question

I think that my problem is a common one, and I'm weighing the costs and benefits of GraphQL as a solution.

I work on a product whose data is stored by a monolithic CRUD-based REST API. We have components of our application expose a search interface for data, and of course need some kind of server-side support for making requests for that data. This could include sorting, filtering, choosing fields, etc. There are, of course, more traditional ways of providing these functions in a REST context, like query parameter add-ons for endpoints, but it would be cool to try out GraphQL in this context to build a foundation for expanding its use for querying a bit.

GraphQL exposes a really nice query language for searching on data, and ultimately allows me to tailor the language of search specifically to my domain. However, I'm not sure if there is a great way to leverage the IDL without managing a separate server altogether.

Take the following Java Jersey API Proof-of-Concept example:

  @GET
  @Path("/api/v1/search")
  public Response search(QueryIDL query) throws IOException {
    final SchemaParser schemaParser = new SchemaParser();

    TypeDefinitionRegistry typeDefinitionRegistry = // load schema
    RuntimeWiring runtimeWiring = // wire up data-fetching classes
    SchemaGenerator schemaGenerator = new SchemaGenerator();
    GraphQLSchema graphQLSchema =
        schemaGenerator.makeExecutableSchema(typeDefinitionRegistry, runtimeWiring);
    GraphQL build = GraphQL.newGraphQL(graphQLSchema).build();

    ExecutionResult executionResult = build.execute(query.toString());

    return Response.ok(executionResult.getData()).build();
  }

I am just planning to take a request body into my Jersey server that looks exactly like the request that would be sent to a GraphQL server. I'm then leveraging some library support to interpret and execute the request for data.

Without really thinking too much about everything that could go wrong, it looks like a client would be able to use this API similar to the way they would use a GraphQL server, except that I don't need to necessarily manage a separate server just to facilitate my search requirements.

Does it seem valuable, or silly, to use the GraphQL IDL in an endpoint-based context like this?

Answer 1

Apart from not needing to rebuild the schema or the GraphQL instance on each request (there are cases where you may want to rebuild the GraphQL instance, but your case is not the one), this is pretty much the canonical way of using it.
It is rather uncommon to keep a separate server for GraphQL, and it usually gets introduced exactly the way you described - as just another endpoint next to your usual REST endpoints. So your usage is legit - not silly at all :)

Btw, I'm not sure what would QueryIDL be... the query is just a string. No need for a special class.