Object Type Definition

Almost all of the GraphQL types you define will be object types. Object types have a name, but most importantly describe their fields.

Example:

const AddressType = new GraphQLObjectType({
  name: 'Address',
  fields: {
    street: { type: GraphQLString },
    number: { type: GraphQLInt },
    formatted: {
      type: GraphQLString,
      resolve(obj) {
        return obj.number + ' ' + obj.street
      }
    }
  }
});

When two types need to refer to each other, or a type needs to refer to itself in a field, you can use a function expression (aka a closure or a thunk) to supply the fields lazily.

Example:

const PersonType = new GraphQLObjectType({
  name: 'Person',
  fields: () => ({
    name: { type: GraphQLString },
    bestFriend: { type: PersonType },
  })
});