How to define an contains using firebase-bolt? - firebase

Question

I'm using firebase-bolt to set my rules.
My bolt:
// ######## CONTENTS
path /contents {
read() = true;
index() = ["dt_created"];
}
path /contents/$id is Timestamped<Contents> {
write() = isSignedIn() && isAllowEdit(this);
}
type Contents {
text : String,
address : String,
organization: String | Null,
location: String | Null,
map_lat : String,
map_lng : String,
num_favorite: Number,
num_comment: Number,
num_denounce: Number,
removed: Boolean,
category_id : String,
user_id : String,
photos: String[]
}
//
// Helper Functions
//
isSignedIn() = auth != null;
isAllowEdit(value) = (prior(value) == null || newData.child('user_id').val() == auth.uid);
I would like the only the owner the post can edit, but anyone can update the counters.
I think :
"contents": {
"$id": {
"num_favorite": {
".write": true
....
Not sure if it's possible. But can I create rules to edit only field with contains ?

Answer 1

This in regular Firebase Security Rules:
"contents": {
"$id": {
"num_favorite": {
".write": true
}
Translates to this on Bolt:
path /contents/$id/num_favorite {
write() = true;
}
This will work, because you're adding a new permission and not trying to remove an existing permission (which is not possible in Firebase's security rules language).
But I would consider separating the vote out into its own higher-level node:
path /favorite_counts/$id {
write() = true;
}
This keeps your security rules simpler and more isolated from each other.