GraphQL streaming type?

Question

I'm playing around with GraphQL-JS right now, wiring it up to a MariaDB backend.

I've figured out how to return an entire result set:

const queryType = new GraphQLObjectType({
    name: 'Query',
    fields: () => ({
        users: {
            type: new GraphQLList(userType),
            resolve: (root, args) => new Promise((resolve, reject) => {
                db.query('select * from users', (err, rows, fields) => {
                    if(err) return reject(err);
                    resolve(rows);
                });
            }),
        }
    })
});

Which is pretty cool, but the library I'm using also lets me stream results, row-by-row.

Does GraphQL have anything to facilitate this?

As far as I can tell, GraphQLList is expecting a full array, and I can only resolve my result set once, not feed using an Emitter or something.

Answer 1

(This is not really a complete answer, but doesn't fit into a comment either)

According to the graphQL spec. it should be possible :

GraphQL provides a number of built‐in scalars, but type systems can add additional scalars with semantic meaning. For example, a GraphQL system could define a scalar called Time which, while serialized as a string, promises to conform to ISO‐8601. When querying a field of type Time, you can then rely on the ability to parse the result with an ISO‐8601 parser and use a client‐specific primitive for time. Another example of a potentially useful custom scalar is Url, which serializes as a string, but is guaranteed by the server to be a valid URL.

So the structure should look like this :

var myStream = new GraphQLScalarType({
    name: "myStream",
    serialize: ...
    parseValue: ...
    parseLiteral: ...
  });
}

Now I guess you could try to return promises/streams and see what happens, but I don't think it is supported yet. Many people are asking for this, and I think I saw a comment from someone on the graphQL team saying that they are looking into this (cannot find it back unfortunately).

A personal opinion, but if it cannot be changed without incorporating that behaviour into the core of graphQL, may show that graphQL as it is today is not that flexible.