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()"
       }
     }
   }
}

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"