Generated typings for optional values differ from the definition of Prisma client typings

[nikolasburk]

When using the Prisma client together with graphqlgen in TS scrict mode, the generated typings for optional fields from the Prisma datamodel and the graphqlgen resolver arguments don't match. Example:

datamodel.prisma

type User {
  id: ID! @unique
  email: String! @unique
  name: String
  posts: [Post!]!
}

type Post {
  id: ID! @unique
  createdAt: DateTime!
  updatedAt: DateTime!
  published: Boolean! @default(value: "false")
  title: String!
  content: String
  author: User!
}

For example, content on Post is optional here. Now consider this GraphQL schema:

scalar DateTime

type Query {
  feed: [Post!]!
  filterPosts(searchString: String): [Post!]!
  post(id: ID!): Post
}

type Mutation {
  signupUser(email: String!, name: String): User!
  createDraft(title: String!, content: String, authorEmail: String!): Post!
  deletePost(id: ID!): Post
  publish(id: ID!): Post
}

type Post {
  id: ID!
  createdAt: DateTime!
  updatedAt: DateTime!
  published: Boolean!
  title: String!
  content: String
  author: User!
}

type User {
  id: ID!
  email: String!
  name: String
  posts: [Post!]!
}

The content field is optional in the createDraft mutation. Now, the generated resolver args from graphqlgen for the input to createDraft look like this:

export interface ArgsCreateDraft {
  title: string
  content: string | null
}

On the other hand, the generated PostCreateInput type for the createPost operation in the Prisma client API looks as follows:

export interface PostCreateInput {
  published?: Boolean;
  title: String;
  content?: String;
  author: UserCreateOneWithoutPostsInput;
}

content here is declared as an optional instead of string | null. As fas as I understand, the optional is interpreted as string | undefined. Now, when implementing the createDraft resolver like so:

createDraft: (parent, { title, content, authorEmail }, ctx) => {
  return ctx.prisma.createPost({
    title,
    content,
    author: {
      connect: {
        email: authorEmail,
      },
    },
  })
},

TypeScript throws this error in strict mode:

src/resolvers/Mutation.ts:15:7 - error TS2322: Type 'string | null' is not assignable to type 'string | undefined'.
  Type 'null' is not assignable to type 'string | undefined'.

15       content,
         ~~~~~~~

  src/generated/prisma-client/index.ts:282:3
    282   content?: String;
          ~~~~~~~
    The expected type comes from property 'content' which is declared here on type 'PostCreateInput'

src/resolvers/Query.ts:14:29 - error TS2345: Argument of type '{ where: { OR: ({ title_contains: string | null; } | { content_contains: string | null; })[]; }; }' is not assignable to parameter of type '{ where?: PostWhereInput | undefined; orderBy?: "id_ASC" | "id_DESC" | "createdAt_ASC" | "createdAt_DESC" |"updatedAt_ASC" | "updatedAt_DESC" | "published_ASC" | "published_DESC" | ... 4 more ... | undefined; ... 4 more ...; last?: number | undefined; }'.
  Types of property 'where' are incompatible.
    Type '{ OR: ({ title_contains: string | null; } | { content_contains: string | null; })[]; }' is not assignable to type 'PostWhereInput'.
      Types of property 'OR' are incompatible.
        Type '({ title_contains: string | null; } | { content_contains: string | null; })[]' is not assignable to type 'PostWhereInput | PostWhereInput[] | undefined'.
          Type '({ title_contains: string | null; } | { content_contains: string | null; })[]' is not assignable to type 'PostWhereInput[]'.
            Type '{ title_contains: string | null; } | { content_contains: string | null; }' is not assignable to type 'PostWhereInput'.
              Type '{ title_contains: string | null; }' is not assignable to type 'PostWhereInput'.
                Types of property 'title_contains' are incompatible.
                  Type 'string | null' is not assignable to type 'string | undefined'.
                    Type 'null' is not assignable to type 'string | undefined'.

 14     return ctx.prisma.posts({
                                ~
 15       where: {
    ~~~~~~~~~~~~~~
...
 24       },
    ~~~~~~~~
 25     })
    ~~~~~

[nikolasburk]

Closing this as a duplicate of #278

Seems like there need to be adjustments made in Prisma client as well as in graphqlgen according to this.