Subselection not recognized

[c-riq]

I added this property to Home in https://github.com/graphcool/graphcool-server-example/blob/master/src/resolvers/Home.ts

perNight: {
    resolve: async ({ id }, args, ctx: Context, info) => {
      const place = await ctx.db.query.place({ where: { id } },"{ pricing { perNight } }")
      return place.pricing.perNight
    },
},

And perNight: Int! to the Home type in schema.graphql

Then running this query in the playground

{
  topHomes {
    perNight
  }
}

returns the error

"Field 'places' of type 'Place' must have a sub selection. (line 2, column 3):\n  places(where: $_where, orderBy: $_orderBy, skip: $_skip, after: $_after, before: $_before, first: $_first, last: $_last)\n  ^"

but this query works as expected

{
  topHomes {
    perNight
    id
  }
}

[marktani]

Thanks a lot for bringing this up! The reason is that the resolver itself assumes the existence of an id (you can see this in the first argument which is { id }). So, if there is no id after all, an error is returned (the error message is not too helpful though).

You can solve this use case by providing a fragment option to the resolver object, which ensures that id is part of the query.

This same situation is already handled in the numRatings field of the Home type:

  numRatings: {
    fragment: `fragment NumRatings on Place { id }`,
    resolve: async ({ id }, args, ctx: Context, info) => {
      const places = await ctx.db.query.places({ where: { id } })
      return places.length
    },
  },

So applying that same logic to perNight leaves us with this:

perNight: {
    fragment: `fragment pricing on Place { id }`,
    resolve: async ({ id }, args, ctx: Context, info) => {
      const place = await ctx.db.query.place({ where: { id } },"{ pricing { perNight } }")
      return place.pricing.perNight
    },
},

This is a great scenario that I should cover here: graphql-boilerplates/node-graphql-server#35

[heymartinadams]

Yes, @marktani, a more specific error message would be helpful 🙌🏼