Allow read of firestore document, if it does not exist - google-cloud-firestore

In Firestore I wan't to allow a read, if the targeted document does not exists. I have tried the following:
service cloud.firestore {
match /databases/{database}/documents {
match /reports/{report} {
allow read: if !exists(/databases/$(database)/documents/reports/{report});
}
}
}
It does not work, the respons is: Missing or insufficient permissions..

In case you're doing this server-side, you might instead query the document's existence using the admin SDK (firestore rules are only applied to the client SDK):
const snapshot = await adminFirestore.doc('reports/non-existent-item').get();
if (!snapshot.exists) {
// handle gracefully
}

This seems to be working.
allow get: if resource == null;

Related

Permissions Problems with Flutter and FireBase FireStore

Can someone please help me I am a complete noob to FireStore and FireBase and am trying to do something simple and FireBase is saying I do not have permission to do it? I am using Flutter. I have the following rules set up in FireBase rules console. I only have one project and one firestore database.
service cloud.firestore {
match /databases/{database}/documents {
match /{document=**} {
allow write: if request.auth != null;
allow read: if true;
}
}
}
I have a collection of users setup which has a uid as the collection parameter and running the following code after signing into flutter anonymously which does not throw an error. UserID is set to a valid value.
void createUser(String userID, String userName, String password) async {
final CollectionReference _users =
FirebaseFirestore.instance.collection("Users");
final data = {"Created": DateTime.now(), "LastLoggedIn": DateTime.now()};
_users.doc(userID).set(data, SetOptions(merge: true));
}
I am getting the following error message
10.3.0 - [FirebaseFirestore][I-FST000001] Write at Users/QUIEvBpJeAgprgEan0S736aKjdk2 failed: Missing or insufficient permissions.
I am using anonymous log ons
even when I use the following rules which is supposed to allow all reading and writing of the data I get the same error:
match /databases/{database}/documents {
match /{document=**} {
allow read, write: if true;
}
}
}
I allowed several minutes to go by between when I set the permissions and before testing. Thanks.
Have you tried the default rule with timestamp :
rules_version = '2';
service cloud.firestore {
match /databases/{database}/documents {
match /{document=**} {
allow read, write: if
request.time < timestamp.date(2023, 11, 25);
}
}
}

Troubleshoot simple custom firebase security rules function

I'm writing a custom cloud function (official documentation) in Firestore security rules that checks to make sure the submitting user is the content owner, per the official documentation.
I'm applying the custom function to the correct path /collection/{documents}/subcollection/{subcollectiondocuments} where every subcollectiondocument has a userId field that's not null. These documents do not have a uid field, but I tried it anyway in 2 and 4 below.
All versions of the custom function below (belongsToRequestor 1,2,3 and 4) generate a "Property resource is undefined on object" error in the Cloud Firestore rules playground simulator.
Do I need to pass something into the custom function, or am I making some other mistake?
rules_version = '2';
service cloud.firestore {
match /databases/{database}/documents {
function belongsToRequestor1() {
return
request.auth.uid == resource.data.userId;
}
function belongsToRequestor2() {
return
request.auth.uid == resource.data.uid;
}
function belongsToRequestor3() {
return
request.auth.uid == request.resource.data.userId;
}
function belongsToRequestor4() {
return
request.auth.uid == request.resource.data.uid;
}
…
match /collection/{documents}/subcollection/{subcollectiondocuments} {
allow update: if
belongsToRequestor1();
// or belongsToRequestor2(); or belongsToRequestor3(); or belongsToRequestor4();
…
} }
I'm not sure how to implement this answer to another question to "…enter the path to an actual document that exists if you want to test your rule that uses its field values." Each document in subcollectiondocuments has an id auto-generated by firebase.
Update: adding database screenshot (with fake data), as requested (properties = collection and reviews == subcollection):
Thanks for any help!

"FirebaseError: false for 'get' # L5" firebase error when using on snapshot or get doc when using firebase emulator [closed]

Closed. This question is not reproducible or was caused by typos. It is not currently accepting answers.
This question was caused by a typo or a problem that can no longer be reproduced. While similar questions may be on-topic here, this one was resolved in a way less likely to help future readers.
Closed 12 months ago.
Improve this question
I am using firestore and firebase auth and I am trying to add custom usernames to my app (I am following this courses, Next.js Firebase Full Course) that connect to the freebase emulator because it is still in development. I have this piece of code that runs in a useEffect that gets the current user uid and then fetch a document from firestore, then checks if it exits and if i does set the username state to the username in the do. Here is the code:
useEffect(() => {
let unsubscribe;
if (user) {
console.log(user.uid);
const ref = doc(db, "users", user.uid);
unsubscribe = onSnapshot(ref, (doc) => {
if (doc.exists()) {
setUsername(doc.data()?.username);
} else {
console.log("No such document!");
}
});
} else {
setUsername(null);
}
return unsubscribe;
}, [user]);
But I always get the error "next-dev.js?3515:32 Uncaught Error in snapshot listener: FirebaseError: false for 'get' # L5". I have tried changing the on snapshot to a get doc but that also gets the same error. I tried making it so it didn't connect to the emulator that fixed it. I'm not sure why but I like to use the firebase emulator. Is there anyway to fix this
Thanks in advance!
The error message “FirebaseError : false for ‘get’ #L5” is saying that security rules are denying the request at line 5 of your security rules. If you have curated your rules like below,
rules_version = '2';
service cloud.firestore {
match /databases/{database}/documents {
match /{document=**} {
allow read, write: if false;
}
}
}
then line 5 has the error as you are not allowing read and write access to anyone.
To fix that you can either change your firestore rules to :
match /{document=**} { allow read: if true; allow write: if true; }
but this allows setting your rules to true to both read and write operations, which means that you allow anybody who knows your project ID to read from, and write to your database which is obviously bad, since malicious users can take advantage of it. It’s true that you can use these settings for a small amount of time for testing purposes, but never in a production environment.
So there is another option in which you can limit access to your database to a fixed amount of time. Today is 1.03.2021, we are limiting the access for exactly one day by:
rules_version = '2';
service cloud.firestore {
match /databases/{database}/documents {
match /{document=**} {
allow read, write: if request.time < timestamp.date(2021, 3, 2);
}
}
}
The most important part when it comes to security rules is the Firebase Authentication, meaning that you can allow access only to the users that are authenticated to perform operations in your database. The rules should look like this:
rules_version = '2';
service cloud.firestore {
match /databases/{database}/documents {
match /{document=**} {
allow read, write: if request.auth != null;
}
}
}
If you need a more granular set of rules, for instance, to allow only the authenticated users, who have the value of the UID equal to the value of UID that comes from to authentication process, to be able to write to their own document, then you should consider using the following rules:
rules_version = '2';
service cloud.firestore {
match /databases/{database}/documents {
match /users/{uid} {
allow create: if request.auth != null;
allow read, update, delete: if request.auth != null && request.auth.uid == uid;
}
}
}
A feature request is filed for this error message to be more precise like “FirebaseError: PERMISSION_DENIED because security rules returned false for 'get' # L5”

Could this be the firestore bug?

I tried many different rules. But I am getting permission error.
But if I add this rule it works
service cloud.firestore {
match /databases/{database}/documents {
match /{document=**} {
allow read, write: if true;
}
}
}
I noticed this. I'm having a problem with the collectionGroup function.
// permission error
this.fs.collectionGroup('screts', ref => ref.where("uid", "==", uid));
// no any error. I getting data
this.fs.doc('channels/zs2wJE3uBR62tqslJJe9').collection('screts').doc('scret_fields')

Firebase Security rules to restrict access on all paths but one?

Question:
For the different top-level firestore collections below, how to restrict access to all but one of the paths?
We are building a data schema in Firestore to support a chat app for teachers across multiple schools.
The top-level firestore collections include:
/siteAdminUsers
/schools
/schools/{schoolId}/teachers
/schools/{schoolId}/chats
Below is the security rules setup we are trying now - where we check for:
valid user auth
expected value exists in userClaim variable request.auth.token.chatFlatList
However, the read listener for /messages is being blocked.
Error message:
FirebaseError: [code=permission-denied]: Missing or insufficient permissions
service cloud.firestore {
match /databases/{database}/documents {
match /{document=**} {
allow read, write: if false;
}
match /schools/{schoolId}/chats/{discussionId}/messages {
allow write: if false;
allow read: if request.auth != null
&& request.auth.token != null
&& request.auth.token.chatFlatList.val().contains($discussionId);
}
}
Details
We are using cloud functions for all data read/write, so for almost every case we can just block all client access.
The one exception is for the chat discussions, where we need to set a snapshot listener in the mobile client to know when there are new messages.
Sub-collection notes:
At a school, there are discussion sessions for school staff (teachers, admins, etc)
/schools/{schoolId}/chats/{discussionId}
Where each discussion-document contains:
list of participant teacher ids
subcollection for actual messages where each document is an indivual posted message:
/schools/{schoolId}/chats/{discussionId}/messages
User Claim code from Cloud Function
Looking at the cloud function logs, we have verified that the userClaim is being set.
return firebaseAdmin
.auth()
.setCustomUserClaims(
uid, {
chatFlatList: 'id1 id2 id3'
}
);
UPDATE #1
Tried the following variation where rules skip/omit the check on userClaim and auth.token.
However, still same permission error.
service cloud.firestore {
match /databases/{database}/documents {
match /{document=**} {
allow read, write: if false;
}
match /schools/{schoolId}/chats/{discussionId}/messages {
allow write: if false;
allow read: if request.auth != null;
}
}
}
I think the issue here is that you are writing a rule on the collection called messages.
All match statements should point to documents, not collections.
https://firebase.google.com/docs/firestore/security/rules-structure
You should try adding /{document=**} after your path to messages, something like:
match /schools/{schoolId}/chats/{discussionId}/messages/{document=**} {
allow write: if false;
allow read: if request.auth != null;
}
This worked for me if I wanted to read and write all collection but not one collection named "backStage";
rules_version = '2';
service cloud.firestore {
match /databases/{database}/documents {
match /{collection}/{document} {
allow read: if true
allow write: if (collection != "backStage");
}
}
}
Here's a solution (seems to be working), which includes the check on chatFlatList user claim variable (from original question) for a substring :
match /schools/{schoolId}/chats/{discussionId}/messages {
allow write: if false;
allow read: if request.auth != null
&& request.auth.token.chatFlatList.matches(discussionId);
}
Figured this out thanks to:
Firebase storage rules based on custom parameters
Here the post shows there is not any $ notation to access the path var. I recall seeing this in a security rules example code example - maybe it's specific to database tiers?
https://firebase.google.com/docs/reference/security/storage/#string
https://regex-golang.appspot.com/assets/html/index.html
Trying some example inputs here, to get an understanding for how to create the regex's.