generate model type for type interchangeability

[hirochachacha]

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type Blog @model {
  id: ID!
  name: String!
  posts: [Post] @connection(name: "BlogPosts")
}
type Post @model {
  id: ID!
  title: String!
  blog: Blog @connection(name: "BlogPosts")
  comments: [Comment] @connection(name: "PostComments")
}
type Comment @model {
  id: ID!
  content: String
  post: Post @connection(name: "PostComments")
}

generates:

src/API.ts in TypeScript.

However generated types aren't interchangeable each other.

src/typeCheck.ts:

import * as API from './API'

type CommentList1 = API.GetCommentQuery['getComment'][]
type CommentList2 = API.ListCommentsQuery['listComments']['items']
type CommentList3 = API.OnCreateCommentSubscription['onCreateComment'][]
type CommentList4 = API.GetPostQuery['getPost']['comments']['items']

let c1: CommentList1
let c2: CommentList2
let c3: CommentList3
let c4: CommentList4

c1 = c2
c1 = c3
c1 = c4

c2 = c1
c2 = c3
c2 = c4

c3 = c1
c3 = c2
c3 = c4

c4 = c1
c4 = c2
c4 = c3

then

$ tsc --noEmit src/typeCheck.ts
src/typeCheck.ts:13:1 - error TS2322: Type '{ __typename: "Comment"; id: string; content: string; post: { __typename: "Post"; id: string; title: string; }; }[]' is not assignable to type '{ __typename: "Comment"; id: string; content: string; post: { __typename: "Post"; id: string; title: string; blog: { __typename: "Blog"; id: string; name: string; }; comments: { __typename: "ModelCommentConnection"; nextToken: string; }; }; }[]'.
  Type '{ __typename: "Comment"; id: string; content: string; post: { __typename: "Post"; id: string; title: string; }; }' is not assignable to type '{ __typename: "Comment"; id: string; content: string; post: { __typename: "Post"; id: string; title: string; blog: { __typename: "Blog"; id: string; name: string; }; comments: { __typename: "ModelCommentConnection"; nextToken: string; }; }; }'.
    Types of property 'post' are incompatible.
      Type '{ __typename: "Post"; id: string; title: string; }' is missing the following properties from type '{ __typename: "Post"; id: string; title: string; blog: { __typename: "Blog"; id: string; name: string; }; comments: { __typename: "ModelCommentConnection"; nextToken: string; }; }': blog, comments

13 c1 = c2
   ~~

src/typeCheck.ts:15:1 - error TS2322: Type '{ __typename: "Comment"; id: string; content: string; }[]' is not assignable to type '{ __typename: "Comment"; id: string; content: string; post: { __typename: "Post"; id: string; title: string; blog: { __typename: "Blog"; id: string; name: string; }; comments: { __typename: "ModelCommentConnection"; nextToken: string; }; }; }[]'.
  Property 'post' is missing in type '{ __typename: "Comment"; id: string; content: string; }' but required in type '{ __typename: "Comment"; id: string; content: string; post: { __typename: "Post"; id: string; title: string; blog: { __typename: "Blog"; id: string; name: string; }; comments: { __typename: "ModelCommentConnection"; nextToken: string; }; }; }'.

15 c1 = c4
   ~~

  src/API.ts:500:5
    500     post:  {
            ~~~~
    'post' is declared here.

src/typeCheck.ts:19:1 - error TS2322: Type '{ __typename: "Comment"; id: string; content: string; }[]' is not assignable to type '{ __typename: "Comment"; id: string; content: string; post: { __typename: "Post"; id: string; title: string; }; }[]'.
  Property 'post' is missing in type '{ __typename: "Comment"; id: string; content: string; }' but required in type '{ __typename: "Comment"; id: string; content: string; post: { __typename: "Post"; id: string; title: string; }; }'.

19 c2 = c4
   ~~

  src/API.ts:530:7
    530       post:  {
              ~~~~
    'post' is declared here.

src/typeCheck.ts:22:1 - error TS2322: Type '{ __typename: "Comment"; id: string; content: string; post: { __typename: "Post"; id: string; title: string; }; }[]' is not assignable to type '{ __typename: "Comment"; id: string; content: string; post: { __typename: "Post"; id: string; title: string; blog: { __typename: "Blog"; id: string; name: string; }; comments: { __typename: "ModelCommentConnection"; nextToken: string; }; }; }[]'.
  Type '{ __typename: "Comment"; id: string; content: string; post: { __typename: "Post"; id: string; title: string; }; }' is not assignable to type '{ __typename: "Comment"; id: string; content: string; post: { __typename: "Post"; id: string; title: string; blog: { __typename: "Blog"; id: string; name: string; }; comments: { __typename: "ModelCommentConnection"; nextToken: string; }; }; }'.
    Types of property 'post' are incompatible.
      Type '{ __typename: "Post"; id: string; title: string; }' is missing the following properties from type '{ __typename: "Post"; id: string; title: string; blog: { __typename: "Blog"; id: string; name: string; }; comments: { __typename: "ModelCommentConnection"; nextToken: string; }; }': blog, comments

22 c3 = c2
   ~~

src/typeCheck.ts:23:1 - error TS2322: Type '{ __typename: "Comment"; id: string; content: string; }[]' is not assignable to type '{ __typename: "Comment"; id: string; content: string; post: { __typename: "Post"; id: string; title: string; blog: { __typename: "Blog"; id: string; name: string; }; comments: { __typename: "ModelCommentConnection"; nextToken: string; }; }; }[]'.
  Property 'post' is missing in type '{ __typename: "Comment"; id: string; content: string; }' but required in type '{ __typename: "Comment"; id: string; content: string; post: { __typename: "Post"; id: string; title: string; blog: { __typename: "Blog"; id: string; name: string; }; comments: { __typename: "ModelCommentConnection"; nextToken: string; }; }; }'.

23 c3 = c4
   ~~

  src/API.ts:674:5
    674     post:  {
            ~~~~
    'post' is declared here.


Found 5 errors.

I hit the problem when I tried to use comment list and comment subscription together.

Current workaround is creating model types manually.

export type Blog = {
  __typename: "Blog",
  id: string,
  name: string,
  posts?: ModelPostConnection | null,
};

export type ModelPostConnection = {
  __typename: "ModelPostConnection",
  items?: Array< Post | null > | null,
  nextToken?: string | null,
};

export type Post = {
  __typename: "Post",
  id: string,
  title: string,
  blog?: Blog | null,
  comments?: ModelCommentConnection | null,
};

export type ModelCommentConnection = {
  __typename: "ModelCommentConnection",
  items?: Array< Comment | null > | null,
  nextToken?: string | null,
};

export type Comment = {
  __typename: "Comment",
  id: string,
  content?: string | null,
  post?: Post | null,
};

// test code

type CommentList = Comment[]

let c: CommentList

c = c1
c = c2
c = c3
c = c4

I'd say these types should be automatically generated by amplify-cli.

Describe the solution you'd like

generate model types.

Describe alternatives you've considered

I have no other ideas.

Additional context

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