Common Database Rules for Firebase

database.rules.json

// No Security

{
  "rules": {
    ".read": true,
    ".write": true
  }
}

// Full security

{
  "rules": {
    ".read": false,
    ".write": false
  }
}

// Only authenticated users can access/write data

{
  "rules": {
    ".read": "auth != null",
    ".write": "auth != null"
  }
}

// Checks auth uid equals database node uid
// In other words, the User can only access their own data

{
  "rules": {
    "posts": {
       "$uid": {
         ".read": "$uid === auth.uid",
         ".write": "$uid === auth.uid"
       }
     }
   }
}

// Validates user is moderator from different database location

{
  "rules": {
    "posts": {
       "$uid": {
         ".write": "root.child('users').child('moderator').val() === true"
       }
     }
   }
}

// Validates string datatype and length range

{
  "rules": {
    "posts": {
       "$uid": {
         ".validate": "newData.isString() 
                       && newData.val().length > 0
                       && newData.val().length <= 140"
       }
     }
   }
}

// Checks presense of child attributes

{
  "rules": {
    "posts": {
       "$uid": {
         ".validate": "newData.hasChildren(['username', 'timestamp'])"
       }
     }
   }
}

// Validates timestamp is not a future value

{
  "rules": {
    "posts": {
       "$uid": {
         "timestamp": { 
           ".validate": "newData.val() <= now" 
         }
       }
     }
   }
}


// Prevents Delete or Update
{
  "rules": {
    "posts": {
       "$uid": {
         ".write": "!data.exists()"
       }
     }
   }
}

// Prevents only Delete
{
  "rules": {
    "posts": {
       "$uid": {
         ".write": "newData.exists()"
       }
     }
   }
}

// Prevents only Update
{
  "rules": {
    "posts": {
       "$uid": {
         ".write": "!data.exists() || !newData.exists()"
       }
     }
   }
}

// Prevents Create and Delete
{
  "rules": {
    "posts": {
       "$uid": {
         ".write": "data.exists() && newData.exists()"
       }
     }
   }
}

This doesn't seem to be correct (checking if the user is a moderator):
".write": "root.child('users').child('moderator').val() === true"

Shouldn't it be this way?
".write": "root.child('users').child('moderator').child(auth.uid).exists()"

Rule to allow only the admin accounts to make an update to the database while allowing global reading access:

{
  "rules": {
    ".read": true,
    ".write": false
  }
}

Hello. @codediodeio
I am creating an application where the users should be able to read the posts and also comment on the posts.
They should also be able to delete or edit their own comments.

However, only the admin should be allowed to make, edit, and delete the posts.
Also, all of my users are required to sign-in in the application.
Please tell me what rules should I set.

may i know how to edit database data through POSTMAN or http request after apply the rules??

You need authenticate using email password by giving them in header fields of the post request and then post data to be updated in json format.

you are awesome. thanks

// Validates timestamp is not a future value

{
  "rules": {
    "posts": {
       "$uid": {
         "timestamp": { 
           ".validate": "newData.val() <= now" 
         }
       }
     }
   }
}

Is it possible to set a rule for timestamp which will check if the timestamp is <= now && >= (now - 1 hours).
i.e i dont want to allow any writes which was posted an hour ago!

I am using these rules at present
{
"rules": {
"Users":{
"$uid":{
".read":"auth != null",
".write": "auth != null && auth.uid == $uid",
}
},
}
}
I want the any authenticated user to see the info while any profile updates should be carried out by the person with the authorised UID. When I run this the access to the read is denied logcat says permission denied

Listen at /Users failed: DatabaseError: Permission denied
and I have a profile page in my app and all the info is blank. However if I click into the info to edit it it will update and display it in the app. Also If I remove the "Users" part from the rules I can see the info but cannot update. Any ideas what the issue is I want to use these rules and all documentation/videos seem to suggest this approach but cannot get them implemented. Also in the rules playground , I can get the read at the path, with the authenticated UID to pass

How to make some users see posts and i added them by uid

try this https://github.com/googlearchive/friendlypix-web/blob/master/database-rules.json

what if I want to make an if statment in rules , How?
for example
user can write in "MyRequests" child if his authUid = (saved Uid in "MyFollowers" child)

what if I want to make an if statment in rules , How?
for example
user can write in "MyRequests" child if his authUid = (saved Uid in "MyFollowers" child)

@hatimmts you can use "( )" to make an if statement in rules, this is really useful when dealing with "| |",

this basically group the rule into a separate unit but all your command are executed at once no matter how you nest the "( )".

you can use root, newData, data, parent(), child() to navigate through different nodes in the database.

Hi can you please help me here
https://stackoverflow.com/questions/67220633/firebase-write-to-parent-rule-if-new-child-key-contains-string

Can you help me? I'm newer so I don't know in deep of this problem. When I used this:
{
"rules": {
".read": "auth != null",
".write": "auth != null"
}
}
It's doesn't worked. It appear a message 401 (Unauthorized)
It worked only for:
{
"rules": {
".read": true,
".write": true
}
}

Only if you authenticate the user , the access is given .Like you need to perform firebase authentication using email password or mobile signin or any other method and then try to access the database .

This doesn't seem to be correct (checking if the user is a moderator): ".write": "root.child('users').child('moderator').val() === true"

Shouldn't it be this way? ".write": "root.child('users').child('moderator').child(auth.uid).exists()"

@bulatgab - Were you able to get this to work? I've tried this but keep getting 401 errors.

Hi all. I am using the Firebase rest API to read/write to Firebase real-time database. e.g. "[path-to-db].json".
How do I set the db rules to be able to freely read from the database, while needing to pass an auth password in URL to be able to write to the database? e.g. "[path-to-db].json?auth=[some-password]"

Nice one, thanks for this...

JUST 2 DOUBT, any help will be highly appreciated.

// Checks auth uid equals database node uid
// In other words, the User can only access their own data
{
"rules": {
"posts": {
"$uid": {
".read": "$uid === auth.uid",
".write": "$uid === auth.uid"
}
}
}
}

DOUBT-1
In the above security rule,
the current logged in user can be able to access (read/write) their node/data.
is my understanding correct??

DOUBT-2
and how can i achieve that when the admin of this firebase logged in, then the admin can be able to write, and other user will not be able to access any write operation???

hi i want know .. how i created key and i cant delet it only . or update . without is child"data"