Firestore security rule get() not work

Question

The solution is in the end of the post. Check it out.

Решение проблемы в конце поста. Дочитайте.

just a simple question: whats wrong with this and why this is not working?

Trying to get access with user who has role 'admin' in users section to the /titles/{anyTitle} but still get

Missing or insufficient permissions.

service cloud.firestore {
  match /databases/{database}/documents {
    match /{document=**} {
      allow write: if false;
      allow read: if false;
    }
    function userCanWrite () {
      return get(/databases/{database}/documents/users/$(request.auth.uid)).data.role == "admin";
    }
    match /titles/{anyTitle=**} {
      allow read: if request.auth != null;
      allow write: if userCanWrite();
    }
  }
}

Here is my database structure

P.S.

I tried another rule from official documents get(/databases/{database}/documents/users/$(request.auth.uid‌​)).data.isAdmin == true;

and this is not working too

UPDATE: CORRECT WAY TO DO IT

Support helped me find the solution this is how you should do:

db structure:

users -> {{ userid }} -> { role: "admin" }

database rule settings:

get(usersPath/$(request.auth.uid)).role == "admin" || get(usersPath/$(request.auth.uid)).data.role == "admin";

Answer 1

You should use $(database) instead of {database} in your code:

get(/databases/{database}/documents/users/$(request.auth.uid)).data.role == "admin";

Answer 2

So the way I've solved it is I've created another Collection Called admins

Then I've just added the uid of the user I needed there as such - Here is my database structure - https://i.imgur.com/RFxrKYT.png

And here is the rules

service cloud.firestore {
  match /databases/{database}/documents {

    function isAdmin() {
      return exists(/databases/$(database)/documents/admins/$(request.auth.uid));
    }

    match /tasks/{anyTask} {
    allow read: if request.auth != null;
      allow create: if request.auth != null;
      allow update: if request.auth != null && isAdmin();
      allow delete: if request.auth != null && isAdmin();
    }
  }
}

You can view my full Open Source project here: https://github.com/metaburn/doocrate

Answer 3

What worked for me was moving the userCanWrite function above my rules. It appears that the function has to be defined before any of the match rules that call it. Maddening :-)

Answer 4

I contacted to the Firebase support to report that bug and they gave me a temporary solution on this. It seems that they are having a bug in their systems on the security rules side. They say that the documentation is ok, but for now we should workaround this way:

get(path).data.field == true || get(path).field == true;

Because the bug is that data object isn't populated, you should check both properties. There's no ETA for launching a solution on this bug, so I asked they if they could give me an advice when they solved this issue, so I'll keep this answer up-to-date with their information.