i want to write firebase realtime database rule where certain user can only write cetain key
ex: user with UID underlined in red can write value of key franchise_active only
user with UID underlined in green can write value of key vendor_active only
both users can read
Sounds possible. Something like this should work:
{
"rules": {
"application_status": {
"$uid1": {
"$uid2": {
"franchise_active": {
".write": "auth.uid === $uid1"
},
"vendor_active": {
".write": "auth.uid === $uid2"
}
}
}
}
}
}
Related
When I try to update data in realtime-database with null, ".validate" in database.rules.json seems to be ignored.
I have a database.rules.json in the following format (not the exact same way, but this shows what I expect at least).
database.rules.json
"data": {
".read": "auth != null",
".write": "auth != null",
".validate": "newData.val() != null"
}
When I update realtime-database with
frontend.js
import { set } from 'firebase/database';
export class PublishService {
...
setWithData(value) {
// suppose dbReference has ref to "data"
// something like ref(this.database, "data")
set(this.dbReference, value);
}
}
where value == null,
I can still update realtime-database with null even though this isn't what I expect.
Is this how realtime-database is supposed to work?
If that's the case, is there any documentation that says that?
The .validate rule is not triggered for data deletions. From the documentation on .validate rules:
the validate definitions are ignored when data is deleted (that is, when the new value being written is null).
So you'll want to check for newData.exists() in the .write rule.
is it possible to give update access to only one specific field ?
users
+ gaglajasdfer32fasfa
- Name: Luke // not allowed to update
- likes: 3 // allowed to update
You will have to specify the rule for each field in that case as shown below:
{
"rules": {
"users": {
"$uid": {
"Name": {
".write": "!data.exists()"
}
}
}
}
}
!data.exists() allows write operation only when it's absent now and hence allowing "Create" operations only and not "update" or "delete".
Checkout the documentation to learn more about security rules.
So I have my Database structured like this, the owner gets set when the group is created and the owner the should have the permission to add other Users to allowed so they can access and edit the data too.
-Groups
|-Groupname
|- Owner: string
|- Allowed: List<string>
|- Data: all the data
So my attempt were these rules but they dont work when I use the playground feature with a saved uid under owner or allowed:
"Groups" : {
"$group": {
".read": "auth != null && (data.child('Owner').val() === auth.uid || data.child('Allowed').val() === auth.uid)",
".write": "auth != null && (data.child('Owner').val() === auth.uid || data.child('Allowed').val() === auth.uid)"
}
}
And would a User still be able to create a new group when these rules would work?
Pictures of the Database and Errors:
First, in the Realtime Database, avoid using arrays and use a map instead.
Change this:
"Allowed": {
"0": "8ZiQGBPFkiZOLgLJBgDeLw9ie9D3",
"1": "KEuhrxnAWXS0dnotjhjFAYUOcm42",
"2": "48yULftKSxgyS84ZJC4hs4ug4Ei2"
}
to this:
"Allowed": {
"8ZiQGBPFkiZOLgLJBgDeLw9ie9D3": true,
"KEuhrxnAWXS0dnotjhjFAYUOcm42": true,
"48yULftKSxgyS84ZJC4hs4ug4Ei2": true
}
Read that linked blog post for more info, but in short, it makes adding/removing users really simple:
const groupRef = firebase.database.ref(`Groups/${groupId}`);
// add a user
groupRef.child("E04HLbIjGDRUQxsRReHSKifaXIr2").set(true);
// remove a user
groupRef.child("KEuhrxnAWXS0dnotjhjFAYUOcm42").remove();
You can also change true to whatever you want. Here are some examples:
false = participant, true = moderator
false = read-only, true = can edit
Role names: "member", "admin", "moderator", etc.
Privilege levels: 0 (member), 500 (moderator), 1000 (owner), etc. (make sure to space these out, you don't want to have to add in a level between 0 and 1 and have to edit your entire database).
The most important point though, is that Realtime Database security rules don't know about arrays. data.val() won't return an array, it will just return a sentinel value that says "non-null object is here!". This means a map is necessary for security rules.
This reference document covers the structure and variables you can use in your Realtime Database Security Rules.
With your proposed rules, you attempt to allow any user in the group to be able to write to the group's data - but you don't manage what they can and can't write to. Any malicious member of a group could add/delete anyone else, make themselves the owner, or even delete the group entirely.
{
"rules": {
"Groups" : {
"$group": {
// If this group doesn't exist, allow the read.
// If the group does exist, only the owner & it's members
// can read this group's entire data tree.
".read": "!data.exists() || (auth != null && (data.child('Owner').val() === auth.uid || data.child('Allowed').child(auth.uid).val() === true))",
"Owner": {
// Only the current owner can write data to this key if it exists.
// If the owner is not yet set, they can only claim it for themselves.
".write": "auth != null && (data.val() === auth.uid || (!data.exists() && newData.val() === auth.uid))",
// Force this value to be a string
".validate": "newData.isString()"
},
"Allowed": {
// Only the owner can edit the entire member list
// For a new group, the owner is also granted write access
// for it's creation
".write": "auth != null && (data.parent().child('Owner').val() === auth.uid || (!data.exists() && newData.parent().child('Owner').val() === auth.uid))",
"$member": {
// Allows the user to remove themselves from the group
".write": "auth != null && auth.uid === $member && !newData.exists()",
// Force this value to be a boolean
".validate": "newData.isBoolean()"
}
},
"Data": {
// The owner and members can edit anything under "Data"
// Currently this includes deleting everything under it!
// For a new group, the owner is also granted write access
// for it's creation
// TODO: tighten structure of "Data" like above
".write": "auth != null && (data.parent().child('Owner').val() === auth.uid || data.parent().child('Allowed').child(auth.uid).val() === true || (!data.exists() && newData.parent().child('Owner').val() === auth.uid))"
}
}
}
}
}
I have a Sign Up Flow using Firebase. When I check if an email already exists in the database, like so:
refUsers.queryOrdered(byChild: "email").queryEqual(toValue: emailText).observeSingleEvent(of: .value, with: { snapshot in
if (snapshot.value is NSNull) {
print("Unique email")
// Move to Password View.
let passwordViewController = self.storyboard?.instantiateViewController(withIdentifier: "PasswordViewController") as! PasswordViewController
self.navigationController?.present(passwordViewController, animated: true, completion: nil)
// Pass the emailText to the last View of the flow.
self.singleton.sharedInstance.emailText = emailText!
}
else {
print("Duplicate email")
}
})
The problem is, I don't have the permission to view /users in the database cause my rule is:
{
"rules": {
".read": "auth != null",
".write": "auth != null"
}
}
I know I can find if an email is a duplicate using Auth.auth().createUser but it's not just email that I'm checking in the sign up flow. I use the same method for unique username, as well. How can I achieve this?
As you can see this is not the best way to do it. You should not manually check if email already exists - Firebase can do that for you when user signs up and why would you not want to use that?
What you need is a different approach. I can think of two ways right now:
First:
You can add a new rule to Firebase, eg:
{
"rules": {
"usernames": {
".read": true,
".write": "auth != null"
},
"emails": {
".read": true,
".write": "auth != null"
}
}
}
What you do here is create a new node named usernames which every user can access and read.
Here you should hold a copy of all usernames that registered users have and when registering check if users username is already inside this node.
Second way:
You could modify your signup flow a bit and let users register without a username. After account is created you let them set a username. With a nice flow it would all look as the same registration form.
UPDATE
With rules above users should be able to read from emails and usernames without being registered. This way you can fetch data and compare if email or username is already in use.
Just make sure that when user registers you insert his email and username into those two nodes.
Though #ZassX answered helped me, I've learned what a good approach for this would be, for those who are confused like me.
The best approach is to keep users data safe in /users with "auth != null" rule. Only show the user's meta data to everyone that includes just the email and password of each user. For example:
Database
{
“metaData”: {
uid: {
“email”: …,
“password”: …
}
},
“users”: {
uid: {
“email”: …,
“password”: …
// other information
}
}
}
Security
{
"rules": {
“metaData”: {
“.read”: true,
“.write”: “auth !== null”
},
“users”: {
“.read”: “auth !== null”,
“.write”: “auth !== null”
}
}
}
The information in metaData can now be matched without a user being authenticated first. Of course, this can get more complex as you add more security but for easy understanding, this is it.
I am using Firebase for a small iOS project and I wonder if the following is possible.
Under a given node "myNode_123" I store data records; each record having the shape below:
[fieldStr: "ABC_xyz", fieldNum: 678]
A record is in fact a subnode.
Now my question is about updating the data, for already existing records.
Someone should be allowed to update a data record only if the new value for fieldNum is higher than the one already there.
And in any case the value for fieldStr should stay as it is.
I have already written some rules to make sure fieldNum is fullfilling my request.
But I still have the issue of fieldStr having the risk of being changed.
Here are my rules:
{
"rules": {
".read": true,
//".write": true
"myNode_123": {
"$Record": {
// Ensure that we are either creating a new record not yet existing,
// or that we are only updating for a higher fieldNum.
".write": "(!root.child('myNode_123/'+$Record).exists()) ||
(root.child('myNode_123/'+$Record).exists() && (newData.child('fieldNum').val() > data.child('fieldNum').val()))"
}
}
}
}
The control of fieldNum is working as I wish. But it is still possible to change fieldStr, which I do not want.
Any advice from a Firebase expert?
Add this under $Record.
{
"rules": {
".read": true,
//".write": true
"myNode_123": {
"$Record": {
// Ensure that we are either creating a new record not yet existing,
// or that we are only updating for a higher fieldNum.
".write": "!data.exists() || newData.child('fieldNum').val() > data.child('fieldNum').val()",
"fieldStr": {
".validate": "!data.exists() || data.val() == newData.val()"
}
}
}
}
}
The !data.exists() will make sure only new data can be written to this location. And data.val() == newData.val() will add an exception to allow writes when the new data is the same as the old data, just in case you want to write the entire object to the Database and include the fieldStr.