Graphql-code-generator: How to generate TS Types where all fields are optional (nullable)

[JakeSummers]

I am attempting to generate types to use inside my graphQl server to make my resolvers easier to maintain. I hoping that I can do that using this project.

I am running into an issue with how optional/mandatory fields are generated. I am hoping that someone can suggest a workaround for me.

Schema:

type Query {
    people(): [Person!]!
}

# FirstName, LastName & BirthDate are manditory.  MiddleName is optional.
Person {
    firstName: String!
    middleName: String
    lastName: String!
    birthDate: BirthDate!
}

BirthDate {
    ...
}

When I generate a typescript class for this object
($(npm bin)/gql-gen --file schema.json --template typescript), I get the following:

export interface Person {
    firstName: String
    middleName?: String
    lastName: String
    birthDate: BirthDate
}
export interface Query {
    ...
}
export interface BirthDate {
    ...
}

Unfortunately, these objects are not extremely useful to me inside my GraphQl resolvers. Inside my resolvers, I populate fields lazily. What I would like to be generated is the following:

export interface Person {
    firstName?: String
    middleName?: String
    lastName?: String
    birthDate?: BirthDate
}
export interface Query {
    ...
}
export interface BirthDate {
    ...
}

To provide complete context, this is an example resolver. You can see that I am getting a compiler error here:

const personResolver: IFieldResolver<any, any> = (parentObject: any,
                                                  args: any,
                                                  context: any,
                                                  info: GraphQLResolveInfo): Promise<Person[]> => {
    const firstName: string = loadFirstNameFromDb(..);
    const lastName: string = loadlastNameFromDb(..);
    const middleName: string|undefined = loadMiddleNameFromDb(..);

    # NOTE: We have a separate resolver for BirthDate.  Birthdate is 
    # not known here.
    #
    # This causes the following TS Error: 
    # 
    #     Error:(7, 15) TS2322: Type '...' is not assignable to type 'Person'.
    #       Property 'birthDate' is missing in type '...'.
    const person: Person = {
        firstName: firstName,
        middleName: middleName,
        lastName: lastName,
    };
    return person
};

const siteResolver: IFieldResolver<any, any> = (parentObject: Person,
                                                args: any,
                                                context: any,
                                                info: GraphQLResolveInfo): Promise<BirthDate> => {
    ...
};

const resolvers: IResolvers = {
    Query: {
        ...
    },
    Person: 
    Order: {
        reports: () => [],
        studies: () => [],
        site: siteResolver,
    },
};

I have read through the other threads on this subject, but am still not sure if my use case is valid. Other threads:

• #155 - TS and Nullable types, again
• #138 - Nullable fields with typescript

Thanks!

[FredyC]

You can always use Partial<Person> to turn all those fields as optional when you need to. I don't think it makes sense change this on a generator side as in your schema you clearly have requirement flag for those fields. Or you can make your own templates I guess :)

[dotansimha]

@FredyC is right, use Partial<Person> to achieve this functionality.

[artem-galas]

Yes you can you Partial<SomeModel> but what you can do if you have nested long object?
For instance:

interface Post {
  id: number,
  creator?: Maybe<Creator>
  latestComment?: Maybe<Comment>
}

interface Creator {
  id: number,
  firstName: string
  email: string,
  createdAt: string,
  updatedAt: string,
}

interface Comment {
  id: number,
  creator: Maybe<Creator>,
  body: string,
  dateTime: string
}

Let's say from GraphQL server I want only few fields from creator

I'm writing tests for my component that could show post. That component have @Input or prop (angular/react) that represent one post.

In test I mocked my post object with only necessary fields for my component, But I got typescript error Field createdAt is missing from Creator type...

So my suggestion is adding config option for generate all field optional.

[GreenGremlin]

This would also be useful for creating mock resolvers for use with graphql-tools' makeExecutableSchema.