firestore: modular doc method returns wrong type (typescript)

[thdk]

[REQUIRED] Describe your environment

• Operating System version: Linux desktop 5.11.0-36-generic 40~20.04.1-Ubuntu SMP x86_64 GNU/Linux

• Browser version: n.a.

• Firebase SDK version: 9.1.1

• Firebase Product: firestore

[REQUIRED] Describe the problem

Steps to reproduce:

Compile the typescript code below using firebase 9.1.1

Relevant Code:

import {
    doc,
} from "firebase/firestore";

import * as types from "@firebase/firestore-types";

import { initializeTestEnvironment } from "@firebase/rules-unit-testing";

initializeTestEnvironment({})
   .then((testEnv) => {
       const firestore = testEnv.unauthenticatedContext().firestore();

       // error on below line: Type 'DocumentReference<DocumentData>' is missing the following properties from type 'DocumentReference<DocumentData>': collection, isEqual, set, update, and 3 more.ts(2740)
       const docRef: types.DocumentReference = doc(firestore, "books/foo");
   });

When I navigate to the typescript declaration file for doc I see the following signatures:

    function doc(firestore: types.FirebaseFirestore, path: string, ...pathSegments: string[]): DocumentReference<DocumentData>;
    function doc<T>(reference: types.CollectionReference<T>, path?: string, ...pathSegments: string[]): DocumentReference<T>;
    function doc(reference: types.DocumentReference<unknown>, path: string, ...pathSegments: string[]): DocumentReference<DocumentData>;

As you can see the return type in the declaration file is DocumentReference which gets imported from @firebase/firestore while in other places in the same declaration file types.DocumentReference is used where types is imported from @firebase/firestore-types.

I would think that the types from @firebase/firestore-types should be compatible with those in firebase/firestore.

[Feiyang1]

@firebase/firestore-types are compat types. They are compatible with firebase/firestore in the sense that they are accepted in functions exported from firebase/firestore, but the types from the 2 packages are not compatible(you can't assign them to each other). Can you use DocumentReference from firebase/firestore instead?

[thdk]

Hi thank you for your reply.

I have change my code now back to using DocumentReference from firebase/firestore. The reason I had started using @firebase/firestore-types package for my types was this comment here #5550 (comment).

I only needed that one FirebaseFirestore type but got too enthusiast and started using CollectionReference and DocumentReference as well.