CODEWITHSUNDEEP
google-cloud-firestorefirebase-security
Lucas Nantes
Lucas Nantes

Reputation: 30

Firestore Rules: Making documents in a collection and all subcollections follow the same rule

I'm making a structure that looks something like this:

users
  user1
  user2
  user3
group
  group1
  group2
  group3
     subcollections1
        subdoc11
        subdoc12
     subcollections2
        subdoc21
        subdoc22

So explaining it, I have a users collection and group collection. All users must be part of one and only one group. A group has a 'members' field which I check if the user is a member or not.

So my rules are something like this for now.

match /groups/{document=**} {
  allow read, write: if resource.data.users[request.auth.uid] != null;
}

My question is, would it accurately check if user is in group1->doc-'members' even when writing to a subcollection or would it check in group1->doc->subcollection->doc-'members' in that case?

Because the members list is only in the groups collection but not in the subcollection so the second situation is not wanted.

Upvotes: 0

Views: 58

Answers (1)

Happy-Monad
Happy-Monad

Reputation: 2002

Although I haven't actually tried, the resource.data variable is a refernce to the document being accessed. So if the path accesses the document /groups/group3/subcollections1/subdoc11 that would be the document referenced by resource.data. Therefore I think you're rule won't work as expected.

Regarding how to implement the desired behavior, note that it's best to define Firestore rules at the most granular level. This would prevent to accidentally grant access when a stricter rule ought to be applied but instead a wider rule is applied. I would suggest something alike this:

match /groups/{groupId} {
  allow read, write: if resource.data.users[request.auth.uid] != null;
}

match /groups/{groupId}/{subcollection}/{documentId} {
  allow read, write: if get(/databases/$(database)/documents/$(groupId)).data.users[request.auth.uid] != null
}

For further reference check this pages about how rules work and sample rules.

Upvotes: 1

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