Zod typing for resolvers when omitting un-selected fields (e.g., using getResolvingFields)

[giseburt]

Hello,

So far I'm really digging GQLoom. It's ideal for a lot of what I'm looking for.

I'm trying to break a bad habit we have at the company I'm working for where they expose the database directly to their schema, so I don't want to use the Drizzle/Prisma/etc. dabs weavers. (Those a great, but for larger projects like this one with federation, we need separation of concerns and changing of the GQL schema and the DB schema to be independent.)

Anyway, I have a great little sample setup, and I'm loving it so far. I'm using Zod and (for now) Drizzle. It's the Zod part I think I'm having issues with.

I just have one small issue that I can't figure out: In order to use getResolvingFields() (actually a modified version I made that traces derived fields and only returns the necessary dependencies) I'll need the Typescript type of the output to have all the fields as optional.

Here's the setup code:

// --- TYPES
export const userInputZ = z.object({
  name: z.string(),
  email: z.email(),
  nickName: z.string().nullable(),
});

export const userZ = z.object({
  id: z.string(),
  ...userInputZ.shape,
});

collectNames({
  UserInput: userInputZ,
  User: userZ,
});

export interface IUser extends z.output<typeof userZ> {}
export interface IUserInput extends z.output<typeof userInputZ> {}


// -- HELPERS

static rowToGqlUser(row: Partial<UserRow>): Partial<IUser> {
  return {
    id: row.id ? String(row.id) : undefined,
    name: row.name,
    email: row.email,
    nickName: row.nickname,
  };
}

function getUserGQL(id: number) : Partial<IUser> | null {
  let selectionSet: SelectedTableColumns<User> =
    selectionSetFromRequestedFields(deriveAwareRequestedFields());

  const row = db.select(selectionSet).from(usersTable).where(eq(usersTable.id, id)).get();
  return row ? this.rowToGqlUser(row) : null;
}


// --- RESOLVER
export const userResolver = resolver.of(userZ, {
  user: query(userZ.nullable())
    .input({ id: z.coerce.number<string>() })
    // .output(userZ.partial().nullable()) // ←- 💣🚨 causes duplicate User issue
    .resolve(({ id }) => getUserGQL(id)), // ←- 💣🚨 type error

  nemail: field(z.string())
    .derivedFrom("name", "email")
    .resolve((user) => {
      return `${user.name} <${user.email}>`;
    }),
});


// -- ETC
export const graphqlSchema = weave(ZodWeaver, asyncContextProvider, userResolver);

If I try to use .output(...) (I've tried many options in there) I get the following out of the GraphQL library:

Schema must contain uniquely named types but contains multiple types named "User".

Oddly enough, I don't want it to make a new GraphQL type, I don't want the GraphQL schema to be changed. It makes the right thing for User right now, with the id, name, and email as non-nullable, I just need the typing to allow me to not have to return them.

I looked through how it's done in the Drizzle and Prisma weavers, and the best I can ascertain is that it just casts to any or some similar 🤷 type. (Maybe I missed something?) I'd prefer to avoid that, as another bad habit I'm trying to prevent is people (or agents) abusing any and as-casts, which both have effects that spread like a virus.

Thank you.

P.S. If you'd like the deriveAwareRequestedFields()) I'd be happy to put it in a PR, but I'm not sure where to put it. It's basically the same as getResolvingFields() except it tracks returnType too to see DERIVED_DEPENDENCIES and instead of adding the requested field it adds the dependencies of those fields.