Custom Sorting

[KyleAMathews]

Didn't see anything in the spec about this. I assume it's coming?

[devknoll]

I believe that something like this popped up in one of @leebyron's slides at ReactEurope. The gist of it is that you would expose the type of sorting that you want through field arguments.

{
  user(id: 4) {
    events(first: 1, order: IMPORTANT) {
      ...
    }
  }
}

That is, GraphQL itself doesn't have any notion of sorting. If you want results to be sorted, you would implement the appropriate arguments and semantics that you want. The reason being that GraphQL is storage and backend independent and can't really reason about that.

[KyleAMathews]

Cool! Seems very reasonable.

[leebyron]

Thanks, @devknoll. Right on point. A field argument like order or orderBy means as much to GraphQL as fooBar. It's just a key/value pair that gets provided to the underlying function.

In the example @devknoll provided, you might imagine the backing function looking something like:

function (user, { first, order }) {
  return doSomeWorkToGetEventsForUser(user, { limit: first, orderByKey: order });
}

Where that function does something interesting like a mongodb, sql, or parse query. where ensures the understood semantics for an ordering is applied.

This is important as different backing stores have different semantics for ordering and different orderings may be more expensive and shouldn't be exposed (e.g. large tables where some columns don't have indexes, or a field that is derived information) so the implementing type system may completely choose how to represent and resolve this.

[gajus]

Would be nice if this somehow got standardised.