Access parent documents field in Firestore rules

Question

I\'m implementing a recipe book in Firestore where every user is able to see all the recipes all users created but only the original author of the recipe is allowed to edit or d

Answer 1

Rules don't cascade, so you'll need to perform whatever checks you need for the document being captured by the Rules.

Generally speaking, {x=**} rules are more often a mistake and the usage of =** only for extremely specific use cases.

From your question, I'm assuming your data mode is something like this:

/ListofRecipes/{recipe_document}/List/{list_document}

In this case, you'll need your Rules to be configured something like this:

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

    function isSignedIn() {
      return request.auth != null;
    }

    match /ListOfRecipes/{recipe} {
        allow read, create: if isSignedIn();
        allow update, delete: if resource.data.creatorUID == request.auth.uid;

        function recipeData() {
            return get(/databases/$(database)/documents/ListOfRecipes/$(recipe)).data
        }

        match /List/{list} {
            allow read: if isSignedIn();
            allow write: if recipeData().creatorUID == request.auth.uid;
        }
    }
  }
}