javascript - Firebase security rules custom field -

my firebase security rules follows:

"users": {       "$uid": {         // grants write access owner of user account uid must match key ($uid)         ".write": "auth !== null && auth.uid === $uid",          // grants read access user logged in email , password         ".read": "auth !== null && auth.provider === 'password'"       }     }, 

in addition, have custom userid, store in users/$uid. example users/$uid follows:

users    /$uid        /email: foo@bar.com        /userid: "foobargayid123456" 

i use userid in other nodes, example node profile_pictures set dependencies:

profile_pictures    /userid        /thumbnail: "datablabla" 

question

how can set security rules in firebase node profile_pictures such user id: users/$uid/userid can .write node profile_pictures/userid

i think you're looking for.

{    "rules": {     "profile_pictures": {       "$userid": {         ".write": "           root.child('users').child(auth.uid).child('userid').val == $userid"       }     }   } }