Graphql-js: Error: Schema query must be Object Type but got: undefined (when schema only has mutation)

[reggi]

This schema is valid and works.

var schema = new GraphQLSchema({
  query: new GraphQLObjectType({
    name: 'Query',
    fields: {
      user: {
        type: userType,
        args: {
          id: { type: GraphQLString }
        },
        resolve: (source, args, context, info) => {
          console.log(source, args, context, info)
          return Promise.resolve({"name": 'meow'})
        }
      }
    }
  }),
  mutation: new GraphQLObjectType({
    name: 'Mutation',
    fields: {
      createUser: {
        type: userType,
        args: {
          name: {
            name: 'name',
            type: GraphQLString
          },
          id: {
            name: 'id',
            type: GraphQLInt
          }
        },
        resolve: (source, args, context, info) => {
          console.log(source, args, context, info)
          return Promise.resolve({"name": 'meow'})
        }
      }
    }
  })
})

When I remove the query schema like this:

var schema = new GraphQLSchema({
  mutation: new GraphQLObjectType({
    name: 'Mutation',
    fields: {
      createUser: {
        type: userType,
        args: {
          name: {
            name: 'name',
            type: GraphQLString
          },
          id: {
            name: 'id',
            type: GraphQLInt
          }
        },
        resolve: (source, args, context, info) => {
          console.log(source, args, context, info)
          return Promise.resolve({"name": 'meow'})
        }
      }
    }
  })
})

I get this error:

Error: Schema query must be Object Type but got: undefined.

Seems like It should be valid for me to create a schema without a query and only mutations. Thoughts?

[leebyron]

It's invalid to create a schema without a query type. http://facebook.github.io/graphql/#sec-Initial-types

Do you have a use case for a write-only GraphQL service? I'm curious.

Closing, but feel free to continue discussion.

[marcuswhybrow]

A microservice with a GraphQL API that simply sends emails would not necessarily need any queries.

[leebyron]

I wouldn't necessarily recommend GraphQL for a microservice like that. You might be better off with something much simpler for such a use case.

[marcuswhybrow]

Would there be a "complexity lower bound" for best practice GraphQL use? Possibly: "at least one query and mutation".

[leebyron]

At least one query :)

[leebyron]

GraphQL's strength is in allowing you to request data in a specific shape and evolve an API over time without breaking existing queries.

Mutations in GraphQL are valuable, but primarily because they offer an API of write-then-read which lets you follow a mutation with a specific query in the same atomic request.

For services that are write-only or have fire-and-forget mutations, you're really not leveraging GraphQL's strengths and so you're "paying" for an abstraction that you're not gaining from.

[reggi]

I'm building a graphql server that doesn't have any queries. Mainly proxy to and from other apis. I'm just setting a simple author query which is nice to have to just test and see if there's connection to the graphql and perform the minimal query. While I'm not a big proponent of needing to have a query. It's not a big issue for me. Just have a project, name, alive, health, or author query that returns a string or boolean.

The author query helps to see if CORS works correctly on our server.

{
  query: new GraphQLObjectType({
    name: 'Query',
    fields: {
      author: {
        type: GraphQLString,
        resolve: (source, args, context, info) => {
          return 'Thomas Reggi'
        }
      }
    }
  })
}

fetch('http://localhost:3000/graphql', {
  method: 'POST',
  mode: 'cors',
  headers: {
    'Accept': 'application/json',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    "query": "{\n  author\n}",
    "variables": null,
    "operationName": null
  })
}).then(function (res){
  res.json().then(console.log)
}).catch(console.error)

[stubailo]

I have some use cases for a server that only has subscriptions and no queries.

[Kielan]

i have the same err with a schema which has only queries and no other types, this should be valid though should it not?