graphQL - type must be Output Type

Turns out I did not import another model I referenced. I had the following code :

myField : {   type : Schema.Types.ObjectId,   ref : 'myRef'}

And I was not importing 'myRef' into the list of the mongoose models for which to use graphQL. Quite simple indeed; although the error message could probably be improved (what is this Output type ? What was undefined ?).

The error

Error: ... field type must be Output Type but got: undefined.

mean, you have a problem with GraphQLFieldConfig.

GraphQLFieldConfig need the type-field. If this field is missing or type-ref is bad (undefined etc.) this error appear.

class GraphQLObjectType {  constructor(config: GraphQLObjectTypeConfig)}type GraphQLObjectTypeConfig = {  name: string;  interfaces?: GraphQLInterfacesThunk | Array<GraphQLInterfaceType>;  fields: GraphQLFieldConfigMapThunk | GraphQLFieldConfigMap;  isTypeOf?: (value: any, info?: GraphQLResolveInfo) => boolean;  description?: ?string}type GraphQLInterfacesThunk = () => Array<GraphQLInterfaceType>;type GraphQLFieldConfigMapThunk = () => GraphQLFieldConfigMap;...type GraphQLFieldConfig = {  type: GraphQLOutputType;  args?: GraphQLFieldConfigArgumentMap;  resolve?: GraphQLFieldResolveFn;  deprecationReason?: string;  description?: ?string;}

http://graphql.org/graphql-js/type/#graphqlobjecttyp