Mapping types

[craigspaeth]

Types that map well

GraphQL	Joi
GraphQLInt	number().integer()
GraphQLFloat	number()
GraphQLString	string()
GraphQLBoolean	boolean()
GraphQLObjectType	object()
GraphQLInputObjectType	object()
GraphQLNonNull	a.required()
GraphQLList	array.items(a, b, c)

Types that don't map well

GraphQL	Joi
GraphQLID	string().guid()
GraphQLInterfaceType	alternatives(a, b)
GraphQLUnionType	alternatives(a, b)
GraphQLEnumType	?

We can potentially specify these in the meta extensions e.g. string().meta({ type: 'id' }), alternatives(a, b).meta({ type: 'interface|union' }), object({ red: 1, green: 2 }).meta({ type: 'enum' }).

Or we can use custom Joi extensions, e.g. string().id(), interface(a, b), union(a, b), enum({ red: 1, green: 2 }).

The advantage of the former is we can easily leverage the extra validation from existing Joi types, the latter is more obvious how it maps to GraphQL.

[craigspaeth]

FWIW right now we use union type in the case of array and alternatives and ignore the rest of the types that don't map well... that might be okay for now.