New to firebase rules. I may be thinking about this all wrong, but anyway, I am trying to create a rule that makes sure that the newData being written to the database does not exist under the node it is being written. To write to the database I am using this code:
self.reference?.child("users").child(userid).setValue(data) {
(error, result) in
if (error != nil) {
completion(true, error!.localizedDescription)
} else {
completion(false, "")
}
}
Here is where I'd like to create the rule:
{
"rules": {
".read": false,
"users": {
".write": //allow write if the newData's keyBasedOnAuthID is not under students already
"$student_id": {
//more rules...
}
},
My incoming newData looks something like this:
{ keyBasedOnAuthID {
uid: auth.uid
name: xxxx
other:{
key: xxx
key: xxx
}
} }
I am writing this data to a node named 'users,' so the final path would be root.child('users').child(newData). The rule I would like to make would prevent users from writing duplicate data to the 'users' node. So I want to get the keyBasedOnAuthID value from the newData and check that it does not already exist.
Is this possible? I've tried many different ways to retrieve the keyBasedOnAuthID from the newData snapshot, but none have worked. Maybe I need a different approach? Any help would be appreciated!
Unfortunately, I'm not sure which language your using.
However, setValue doesn't create duplicates: either creates or updates data for the given path.
So, if you don't want to update existing data, you need to check for existence before calling your setValue method in your application code.
Related
I'm trying to implement a Firebase rules read restriction in a data model that has a few nested dynamic child nodes.
I have the following data model:
/groupMessages/<groupId>/<messageId>/
{
"senderId": "<senderId>",
"recipientId": "<recipientId>",
"body": "..."
}
groupId, messageId, senderId and recipientId are dynamic ids. I would like to attach a listener to the /groudId node to listen to new messages. At the same time I only want users to read the message where the senderId or recipientId matches a corresponding auth.token value.
Due to Firebase cascading rules, if I allow the read at the groupId level without restrictions, I can't deny them on the message level.
{
"rules": {
"groupMessages"
"$groupId": {
".read": "auth != null"
}
}
}
}
I also haven't found a way to restrict the read rule on the groupId level to check for sender/recipientId of a message.
Any suggestions greatly appreciated.
As you've found, security rules cannot be used to filter data. But they can be used to restrict what queries can be performed on the data.
For example, you can query for all messages where the current user is the sender with:
var query = ref.child("groupMessages").child(groupId).orderByChild("senderId").equalTo(uid);
And you can secure access to the group's messages to only allow this query with:
{
"rules": {
"groupMessages": {
"$groupId": {
".read": "auth.uid != null &&
query.orderByChild == 'senderId' &&
query.equalTo == auth.uid"
}
}
}
}
The query and rules now exactly match, so the security rules will allow the query, while they'd reject a broader read operation. For more on this, see query based rules in the Firebase documentation
You'll note that this only works for a single field. Firebase Database queries can only filter on a single field. While there are workarounds by combining multiple values into a single property, I don't think those apply to your scenario, since they only work for AND queries, where you seem to want an OR.
You also seem to want to query on /groupMessages instead of on messages for a specific group. That also isn't possible: Firebase Database orders/filters on a property that is at a fixed path under each child of the node where you run the query. You cannot query across two dynamic levels, as you seem to be trying. For more on this see: Firebase Query Double Nested and Firebase query if child of child contains a value.
The common solution for your problem is to create a list of IDs for each user, which contains just the IDs of all messages (and/or the groups) they have access to.
userGroups: {
uid1: {
groupId1: true,
groupId2: true
},
uid2: {
groupId2: true,
groupId3: true
}
}
With this additional data structure (which you can much more easily secure), each user can simply read the groups they have access to, and your code then reads/queries the messages in each group. If necessary you can add a similar structure for the messages themselves too.
Finally: this type of recursive loading is not nearly as inefficient as many developers initially think, since Firebase pipelines the requests over an existing connection.
I am using Firebase Realtime Database. And I have a structure to prevent to many children. I have 2 keys. One for the max(max_people), and one that contains how many children there are (registered_people).
My structure:
I have the max_people key. This is the max children that can be in the approved key. Registered_people is counting how many childs there in the approved key.
This is my security rule:
"registrations": {
"approved": {
".write": "(root.child('/agenda/activitys').child($room_id).child('max_people').val() > root.child('/agenda/activitys').child($room_id).child('registered_people').val())"
}
What I do at my firebase rules, is that I check if there not are to many rows. If there are to many I block the writing. This works as expected.
But now the problem, the max_people is for example 20, and the registered_people is also 20. No writes can happen. Because I have declared that. But how can I allow a delete than. Because I want to delete at every moment.
So in short, I want to delete no matter what. And I want to write with my current rule.
Some more information:
I add data to the key with the following code:
let data = [
"full_name": "test",
"email_addres": "test",
]
Database.database().reference().child("agenda/activitys/" + event + "/registrations/approved").child(Auth.auth().currentUser!.uid).setValue(data) { (error, ref) in
print("got from subscribing \(String(describing: error))")
if((error) != nil){
completionHandler(Result.failure(ApiError.noMorePlaces))
return
} else {
completionHandler(Result.success("succes \(event)"))
return
}
}
Adding works as expected.
And I delete data with the following code:
Database.database().reference().child("agenda/activitys/" + event + "/registrations/approved").child(Auth.auth().currentUser!.uid).removeValue { (error, ref) in
if((error) != nil){
completionHandler(Result.failure(ApiError.unknownError))
return
} else {
completionHandler(Result.success("succes \(event)"))
return
}
}
Deleting does not work as expected. I get a permission_denied error when there are for example a max of 20 keys. And that max is fully used (so I have 20 keys with data under the approved child).
Error:
[Firebase/Database][I-RDB038012] setValue: or removeValue: at /agenda/activitys/Jumping Fitness/registrations/approved/exCnADF43AdFUzGsi0GllEsZJZY2 failed: permission_denied
However deleting works when there a less than the max amount of keys.
Edit:
I have tested the suggested solution on the firebase rules simulator. I got the simulated write error there also.
I think that I have the solution. I delete on the key, so on the rules I need the key also. My solution:
"registrations": {
"approved": {
".write": "(root.child('/agenda/activitys').child($room_id).child('max_people').val() > root.child('/agenda/activitys').child($room_id).child('registered_people').val())",
"$key" : {
".write" : "!newData.exists()"
}
}
When data is being deleted, the newData variable will be null. So you can check if it exists using the exists() method:
"registrations": {
"approved": {
".write": "(root.child('/agenda/activitys').child($room_id).child('max_people').val() > root.child('/agenda/activitys').child($room_id).child('registered_people').val()) || !newData.exists()"
}
Update: After looking at the code you provided, I can see that you do the write operations against the child key. But have in mind that, according to the documentation:
Shallower security rules override rules at deeper paths.
This means that the write rule under "approved" will overwrite the write rule at "$key". So you should join both rules and keep them under the "$key" rule. Like this:
"registrations": {
"approved": {
"$key" : {
".write" : "(root.child('/agenda/activitys').child($room_id).child('max_people').val() > root.child('/agenda/activitys').child($room_id).child('registered_people').val()) || !newData.exists()"
}
}
I am stuck trying to allow an an array of admins access to their data.
I have a database structure like this:
{
"Respondents": {
"Acme Corp": {
"admins": ["mMK7eTrRL4UgVDh284HntNRETmx1", ""mx1TERNmMK7eTrRL4UgVDh284Hnt"],
"data": {data goes here...}
},
"Another Inc": {
"admins": ["Dh284HmMK7eTrRL4UgVDh284HntN", ""x1TERNmx1TERNmMK7eTrRL4UgVDh"],
"data": {their data goes here...}
}
}
}
And then I tried to set my rules like this
{
"rules": {
"Respondents": {
"$organisation" : {
".read": "root.child('Respondents').child($organisation).child('admins').val().includes(auth.id)",
".read": "root.child('Respondents').child($organisation).child('admins').val().includes(auth.id)"
}
}
}
}
..but that won't parse in the Firebase Database Rules editor
I get "Error saving rules - Line 7: No such method/property 'includes'", but I need something to match the user id with the array of admins.
Any experience or suggestions?
As you've found, there is no includes() operation in Firebase's security rules. This is because Firebase doesn't actually store the data as an array. If you look in the Firebase Database console or read this blog post you will see that Firebase stores it as a regular object:
"admins": {
"0": "mMK7eTrRL4UgVDh284HntNRETmx1",
"1": "mx1TERNmMK7eTrRL4UgVDh284Hnt"
}
And since that is a regular JavaScript object, there is no contains() method on it.
In general creating arrays are an anti-pattern in the Firebase Database. They're often the wrong data structure and when used are regularly the main cause of scalability problems.
In this case: you're not really looking to store a sequence of UIDs. In fact: the order of the UIDs doesn't matter, and each UID can be meaningfully present in the collection at most once. So instead of an array, you're looking to store set of uids.
To implement a set in Firebase, you use this structure:
"admins": {
"mMK7eTrRL4UgVDh284HntNRETmx1": true,
"mx1TERNmMK7eTrRL4UgVDh284Hnt": true
}
The value doesn't matter much. But since you must have a value to store a key, it is idiomatic to use true.
Now you can test whether a key with the relevant UID exists under admins (instead of checking whether it contains a value):
"root.child('Respondents').child($organisation).child('admins').child(auth.uid).exists()",
I am currently creating Firebase security rules to prevent a user from setting a node to null and deleting all the data in that node.
This is my schema
{
"folder" : {
"item1" : {
"dataset1" : {
"data1" : 123,
"data2" : 456,
"data3" : 789
}
}
}
}
These are my rules
{
"rules": {
"folder": {
// users cannot delete items in the node folder
".write": "newData.exists()",
// item is a variable
"$item": {
"dataset1": {
// dataset1 must have certain nodes and can't be deleted (set to null)
".validate": "data.hasChildren(['data1', 'data2', 'data3']) && newData.exists()",
"data1": {".validate": "newData.isNumber()"},
"data2": {".validate": "newData.isNumber()"},
"data3": {".validate": "newData.isNumber()"},
// using the variable $other means any node that isn't data1, data2, data3 is denied
"$other": {".validate": false}
}
}
}
}
}
Using the built in simulator I'm getting these results:
This works when location is set to "/folder/item1" and "/folder/item1/dataset1"
If I had deeper nodes in data1 they would all be deleted because the write was allowed.
Thanks for taking a read. Open to any answers, preferably I don't need to change the schema.
It's not really clear to me what you're asking. But there are a few problems with your rules, so I'll just point those out in hopes that they answer your question.
you grant write access on /folder, which you cannot take away at a lower level.
As long as any data is left under /folder any write is allowed. A thing to keep in mind is that newData is the data at the location as it will exist after the write operation; it is not just the new data that is written.
I have the impression that you're trying to prevent the deletion with .validate rules. Keep in mind that validation is not performed when deleting data, so you cannot use .validate rules to prevent deletion.
I suspect that #2 is causing your current problem.
I'm having an issue setting my Security rules properly, specifically reading the post data.
The data hierarchy goes:
posts : {
0 : {
title: "Post One",
userId: 6
}
},
users : {
6 : {
name: "My Name"
}
}
And my rules are:
{
"rules": {
"posts" : {
"$post": {
".read":"data.child('userId').val() == auth.id",
".write":"newData.child('userId').val() == auth.id"
}
},
"users":{
"$user": {
".read":"auth.id == $user",
".write":"auth.id == $user"
}
}
}
}
I know that the "auth.id" is 6, because it's pulling the rules correctly for my user info. If I change the rules to pull the number statically, it works:
"$post": {
".read":"data.child('userId').val() == 6",
".write":"newData.child('userId').val() == auth.id"
}
but using auth.id does not. Is there something I'm missing?
One thing to keep in mind is that security rules are type-safe. In particular, In the rules, "6" != 6 (since one is a string and one is a number). So perhaps your auth.id is "6" (as a string), but your userId is 6 as a number?
If that's the case, one potential fix would be changing your rule expression to something like:
data.child('userId').val() + '' == auth.id
which will force userId to be a string. Alternatively, you could change your data to make sure userId is always stored as a string.
You haven't included the code you're using to look up this data--probably where the error is--or the error you are receiving; those would help quite a bit.
Your rules should work fine, assuming you are attempting to read a single post at a time, and assuming your authentication is set up correctly.
A quick guess would be that you're trying to read the entire "posts" path, and using security rules to filter your posts. But security rules are essentially atomic. If you try to read "posts", and one of the posts has a rule that prevents read, the entire operation is going to fail.
Instead, you need to segment the posts into paths where all the data can be read by the authenticated user, then you can apply security rules accordingly.
One thing that will help immensely is to test your security rules by going into your Forge and using the "simulator". You can log in as any user, then try a read/write, and see exactly which security rules is failing and why.