Doesn't follow GraphQL spec

[stubailo]

Hey, I just checked out the demo, and it looks like the query language is similar to GraphQL in syntax, but doesn't follow many critical parts of the specification, meaning it won't be able to work with GraphQL clients such as Apollo Client and Relay that expect spec-compliant results.

For example, this query:

{
  me(_xid_: m.0bxtg) {
    type.object.name.en
    film.actor.film {
      film.performance.film {
        type.object.name.en
        type.object.name.ru
      }
    }
  }
}

Returns the following result:

{
  "_uid_": "0xcbcefccffb9eb400",
  "film.actor.film": [
    {
      "_uid_": "0x127e8b8ee91e3a5",
      "film.performance.film": [
        {
          "_uid_": "0x210ee792fe791347",
          "type.object.name.en": "Catch Me If You Can",
          "type.object.name.ru": "Поймай меня, если сможешь"
        }
      ]
    },
  ...

There are at least problems with this query/result combination:

1. There is no me field at the root of the result, meaning the results we get don't match the shape of the query
2. There are many _uid_ properties in places where the query didn't ask for them

I realize the GraphQL support roadmap item is not complete, but the checked off tasks imply that basic query support is complete. I think it would be much better to follow the query specification so that this database can be interoperable with other GraphQL tools.

[manishrjain]

Yeah, I know that our implementation of GraphQL isn't exactly as mentioned in the spec. This is because GraphQL is meant as a REST API replacement, and not really a graph query language. So, we're making modifications to it to ensure it can operate as a full-fledged graph query language.

A good example of this is mutations. GraphQL doesn't contain all the data or the instructions required to specify how to write data, as that part is generally given away to a Relay JS function. GraphQL just tells you which function to call and the params. That doesn't work for us, because we're language agnostic, and implement GraphQL at a systems level. So, we've had to modify the mutations to fit our purpose.

At some point, once we're mature enough and have better understanding and implementation of GraphQL, we can release our mods to the official spec; and see whether they should live separately or be merged into the official GraphQL spec.

Keeping that in mind, regarding 1, we use me or anything for that matter, just to act as the root. We can fix it to match GraphQL standards.

Re: 2, the _uid_s are important to uniquely identify the entities involved. This is the one field that always gets sent back, so the user can form further queries based on this. You can ignore these.

[stubailo]

Yeah, I know that our implementation of GraphQL isn't exactly as mentioned in the spec.

I would argue it's a bit misleading to specify that you are using GraphQL as the query language, even though it is not compatible with any GraphQL tools.

[manishrjain]

hmm... How do you suggest we modify our language to communicate that we use GraphQL, but only to the point where we modify it to fit the needs of a Graph Database?

[stubailo]

I guess I think you can achieve most of your goals while still sticking to the GraphQL specification - for example, having me in the root of the response, not returning fields that aren't asked for (the user can ask for UIDs if they need them to form more queries), etc.

There are some very minor things like I don't think GraphQL allows dots in field names, which is much less important. But I think the greatest strength of the GraphQL ecosystem is that it's a well-defined standard, and there are lots of tools to work with that data. So if I hear that something supports GraphQL, I would expect that it follows all of the specification.

It would be kind of like saying that your response is JSON, but that you don't think commas are a good array separator and using spaces instead - it's like JSON, but no tools with JSON will be able to consume the data.

That doesn't work for us, because we're language agnostic, and implement GraphQL at a systems level. So, we've had to modify the mutations to fit our purpose.

For example, why not just have the mutation accept an array of strings, or a string query? Or just a standard set of arguments, like an object with fields to be set?

[stubailo]

The place I'm coming from is that I'm a maintainer of an in-development GraphQL client, an alternative to Relay: https://github.com/apollostack/apollo-client

I think it would be exciting if developers could use tools like Relay or Apollo to work with data from dgraph.

[manishrjain]

Good points, and valid points.

Can you have a look at our test queries and see if the modifications that you propose would allow us to achieve compatibility with your tools:
https://discuss.dgraph.io/t/list-of-test-queries/22

Honestly, my concern here is that we're figuring out about GraphQL as we're moving forward. And I just don't know to what extent can we push it to behave like a Graph language and yet remain within its specs. If we're going to deviate anyway, I don't want to push too hard to stay within the specs. OTOH, if there is a convergence path, then I'm all for it. GraphQL ecosystem is surely growing, and we'd love to be part of that.

[stubailo]

Yeah I'll give those a look!

I think if you find that GraphQL doesn't work as a language for your database (I'll admit it is a bit misleadingly named because it isn't really a query language for graphs), it could be good to rephrase the documentation and marketing to say "uses a query language similar to GraphQL" so that people know what to expect.

[manishrjain]

Added a task for this: https://trello.com/c/FaD13zPU

Closing this issue for now. Please reopen if needed.

[manishrjain]

https://wiki.dgraph.io/index.php?title=Beginners%27_guide#Queries_and_Mutations

Hey @stubailo : Added a note here. But, I've been thinking about this over the past days. A lot of people get interested in Dgraph because of GraphQL, and so I think it would be worth our effort if we try to bring our implementation as close to the spec as possible.

So, in that direction, I wanted to get your ideas about some Graph use cases and how GraphQL would handle them. Possible to do a quick video chat?