Incorrect type definitions in hooks?

Seems like the type definitions for useFirestoreDoc and useFirestoreCollection are incorrect:

export declare function useFirestoreDoc<T = unknown>(ref: firestore.DocumentReference, options?: ReactFireOptions<T>): firestore.DocumentSnapshot | T;

In a union, unknown absorbs everything, so if we don’t pass a generic type here the return type will always be unknown. I tried to find a way to fix this so I could do a PR myself, but I’m afraid my TypeScript knowledge is lacking.

If I understand correctly, what we want here is to make the return type be firestore.DocumentSnapshot by default, or T if specified. I opened a PR with a way to do this but I’m really not sure if this is how it’s supposed to be done.

Version info

React: 16.8.6

Firebase: 6.0.4

ReactFire: 2.0.0-canary.fc2be5b

Typescript: 3.5.3 (on my machine) and 3.3.3 (on CodeSandox) both show the same problem

Test case

Test case on Code Sandbox

I didn’t try to make the project actually run, because the issue is just the type definitions. The issue isn’t visible right away, though, because reactfire can’t import from firebase/app on Code Sandbox for some reason. Follow these steps to see the problem:

Steps to reproduce

1. Visit https://codesandbox.io/s/reactfire-typescript-wrong-types-4wq4o
2. Open the file src/withoutOptions.ts
3. Right-click useFirestoreDoc and select “Go To Definition”"
4. Check if the firebase/app import is failing. If it is, replace with just firebase. Don’t save the file, but leave it open (important).
5. Go back to src/withoutOptions.ts and check the type of doc by hovering the mouse over it.

Expected behavior

The type should be firestore.DocumentSnapshot by default

Actual behavior

The type is unknown

[codediodeio]

Here’s another option.

It does not make much sense to use a generic because <Collection|Document>Snapshot does not take a generic to begin with. TBH, I’d rather not have a union type and just manually cast the type to the data.

OR

The hook could return an object with the QuerySnapshot in addition to the data cast to the generic type, for example:

interface ReactfireCollection<T> {
  snapshot?: firestore.QuerySnapshot,
  data?: T[]
}

// Usage would look like this:

const { snapshot, data } = useFirestoreCollection<Dog>(ref);
const { snapshot: catSnap, data: catData, } = useFirestoreCollection<Cat>(ref);

Benefits:

1. Eliminates the need for the extra data hooks.
2. Easy to strongly type. Data would take initialValue, so you don’t need union types at all.

[jamesdaniels]

Yeah, I’m calling this one good. Open a new issue for any type problems you experience as of the latest RCs.