Firestore Database Rules and Structure for sharing Documents between users

Question

I\'m trying to create an application which allows users to collaborate on lists. Every user needs to be invited in order to be able to work on the list.

I structured

Answer 1

I was able to figure it out.

I changed the data structure to this:

list
  list_1
    owner: owner@company.com
    writeAccess: [user1@company.com, user2@company.com]
    id
    name
    items:
      item_1:
        id:
        name:
      ...

Then the database rules like this are working:

service cloud.firestore {
  match /databases/{database}/documents {
    match /lists/{listId} {
        // Allow RW on lists for owner, shared user or for everyone if it's a new list
      allow read, write: if resource.data.owner == request.auth.token.email ||
                            request.auth.token.email in resource.data.writeAccess ||
                            !exists(/databases/$(database)/documents/lists/$(listId))
    }
    match /lists/{listId}/items/{itemId} {
        // Allow RW on item for owner or shared user of parent list
        allow read, write: if get(/databases/$(database)/documents/lists/$(listId)).data.owner == request.auth.token.email ||
                              request.auth.token.email in get(/databases/$(database)/documents/lists/$(listId)).data.writeAccess ||
                             !exists(/databases/$(database)/documents/lists/$(listId)) // Needed for new lists. Because lists and items are created in a batch
    }
  }
}