Develop Reference

Unable to write on firestore emulator

I was able to read data from the firestore emulator but cannot add any data to it throught the client which is an android app.
This is the error:
W/Firestore: (24.0.0) [Firestore]: Write failed at Users/vBLloPGsMJrXGDZdZcVO: Status{code=PERMISSION_DENIED, description=Missing or insufficient permissions., cause=null}
My firestore.rules file in local environment
rules_version = '2';
service cloud.firestore {
match /databases/{database}/documents {
match /{document=**} {
allow read, write: if true;
}
}
}
This is the code used to write to firestore
FirebaseFirestore.getInstance().collection("Users")
.document(userId)
.set(newUser)
.addOnCompleteListener(new OnCompleteListener<Void>() {
#Override
public void onComplete(#NonNull Task<Void> task) {
if (task.isSuccessful()){
Log.d(TAG, "new user has been added");
}else {
Log.d(TAG, "Failed to add new user"+Objects.requireNonNull(task.getException()).getMessage());
}
}
});

Looks like you're trying to update a document (different from writing one). Try to add "update" in your firestore security rules like so:
allow read, get, update: if true;

Use Anonymous Login in Firebase to Auth a user on Firestore

I'm a bit lost, I'm writing an android app that will give new users who are not yet signed-in to read some data from firestore, so I set up anonymous login and I want to authenticate the anonymous user using firebase-auth, once the user is authenticated I want to use his uid/cred to get access to the firestore database.
Firebase auth:
mAuth = FirebaseAuth.getInstance();
mAuth.signInAnonymously()
.addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
#Override
public void onComplete(#NonNull Task<AuthResult> task) {
printWithDash("INSIDE onComplete");
if (task.isSuccessful()) {
// Sign in success, update UI with the signed-in user's information
printWithDash("SIGN IN SUCCESSFULL");
FirebaseUser user = mAuth.getCurrentUser();
printWithDash(user.toString()); // address
} else {
// If sign in fails, display a message to the user.
printWithDash("SIGN IN FAIL!!!");
}
}
});
And here's how I write to firestore:
db.collection("answers")
.add(jsonAnswers)
.addOnSuccessListener(new OnSuccessListener<DocumentReference>() {
#Override
public void onSuccess(DocumentReference documentReference) {
System.out.println("-----------------------------------------------------------------------------------------");
System.out.println("DocumentSnapshot added with ID: " + documentReference.getId());
System.out.println("-----------------------------------------------------------------------------------------");
}
})
.addOnFailureListener(new OnFailureListener() {
#Override
public void onFailure(#NonNull Exception e) {
System.out.println("Error adding document " + e);
}
});
here are my firetore rules
service cloud.firestore {
match /databases/{database}/documents {
match /{document=**} {
allow read: if request.auth.uid != null && request.auth.token.firebase.sign_in_provider == 'anonymous';
allow write: if request.auth.uid != null && request.auth.token.firebase.sign_in_provider == 'anonymous';
}
}
}
I'm new to android development, how does authentication works on android apps?. And how can I use my anonymous user to write to firestore db?

Put only the request.auth.uid != null; to able read and write the signed in anonymous users:
service cloud.firestore {
match /databases/{database}/documents {
match /{document=**} {
allow read, write: if request.auth.uid != null;
}
}
}
A users who sign in anonymously are also authenticated.

I've learned that signing anonymously will save your user cred on the phone itself, look at the device file explorer under apps/ your app. so once we did the anonymous login , the user is considered authenticated until you will do mAuth.signOut();

Check for document existence in Firestore

I'm trying to find if some item exists in my database.
If it does not exist, I had like to add it.
If it exists, I had like to show a message.
The code im using:
CollectionReference colRefMyBooks = db.collection( "Users" ).document( auth.getUid() ).collection( "MyBooks" );
Query queryMyBooks = colRefMyBooks.whereEqualTo("BookID", bookId);
queryMyBooks.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
#Override
public void onComplete(#NonNull Task<QuerySnapshot> task) {
if (task.isSuccessful()) {
for (QueryDocumentSnapshot document : task.getResult()) {
Toast.makeText(BookDetailActivity.this, "Book already in my list", Toast.LENGTH_SHORT).show();
}
} else {
db.collection( "Users" ).document( auth.getUid() ).collection( "MyBooks" ).add( general_book );
}
}
});
This code works good as long as there is a collection "MyBooks". However, if there is no collection "Mybooks" I want it to consider it as the task is not successful and therefore to add the item.
What I do get is that it skips the whole onComplete and therefore does not add anything.
Does it mean that I have to check first if a collection exists and inside of it if document?
Thank you

A query that finds no documents will always be considered "successful", regardless of whether or not any collections exist. This behavior can't be changed.
What you'll have to do instead is check if there are no documents in the result set and decide what you want to do from there:
queryMyBooks.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
#Override
public void onComplete(#NonNull Task<QuerySnapshot> task) {
if (task.isSuccessful()) {
QuerySnapshot snapshot = task.getResult();
if (snapshot.isEmpty()) {
db.collection( "Users" ).document( auth.getUid() ).collection( "MyBooks" ).add( general_book );
}
else {
for (QueryDocumentSnapshot document : snapshot) {
Toast.makeText(BookDetailActivity.this, "Book already in my list", Toast.LENGTH_SHORT).show();
}
}
}
}
});
Note that collections don't really "exist". There are no operations to add or delete collections. There are just operations to modify documents. A collection only appears in the console if it contains at least one document. If it contains no documents, it just disappears.

Simulation Rules - access allowed; Android - access denied

I have a rule which executes correctly in Firestore Rules simulation as seen below.
The /config/permissions document is many arrays named X153, X154, X155, etc., which contain UIDs:
When I attempt this access in Android, I get a PERMISSION_DENIED response.
Code:
DocumentReference docRef = db.collection("arcs").document("X153");
docRef.get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
#Override
public void onComplete(#NonNull Task<DocumentSnapshot> task) {
if (task.isSuccessful()) {
DocumentSnapshot document = task.getResult();
if (document.exists()) {
Log.d("FIREBASE", "DocumentSnapshot data: " + document.getData());
} else {
Log.d("FIREBASE", "No such document");
}
} else {
Log.d("FIREBASE", "get failed with ", task.getException());
}
}
});
The UID used in simulation is the same as in Android:
If I set the rule to authenticate access of the UID directly
Android permission accepted, returns document.
If I flatten out the config/permissions structure to just key/values, like X153 : '9iXQBaG3Ycaey4cFUj8tZjhKMaB3', and change the rule to
match /arcs/{x} {
allow read: if request.auth.uid == get(/config/permissions).data[x];
}
Android returns PERMISSION DENIED.
Why am I receiving this PERMISSION DENIED response using the rule pictured?

Querying Firestore for uid document after authentification => IllegalStateException

I am using both Firebase Authentification and Firestore for my Android app. What I am trying to do is the following:
the user signs in
if it's the first time the user signs in a document named by his uid is created
if the user has already signed in before (hence document named by uid already exists) then I load some further data.
Here's my logic to solve this:
get the FirebaseUser from FirebaseAuth instance
from the FirebaseUser I get the uid
build a DocumentReference with this uid
use get() query on the DocumentReference
if DocumentSnapshot is != null then user already exists in firestore
if DocumentSnapshot == null the user doesn't exist and I create it in firestore
I was testing the code below:
FirebaseUser user = mAuth.getCurrentUser();
if(user != null) {
// get uid from user
String uid = user.getUid();
// make a query to firestore db for uid
DocumentReference userDoc = db.collection("users").document(uid);
userDoc.get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
#Override
public void onComplete(#NonNull Task<DocumentSnapshot> task) {
if (task.isSuccessful()) {
DocumentSnapshot document = task.getResult();
if (document != null) {
Log.d(LOG_TAG, "DocumentSnapshot data: " + task.getResult().getData());
} else {
Log.d(LOG_TAG, "No such document");
}
} else {
Log.d(LOG_TAG, "get failed with ", task.getException());
}
}
});
}
When uid exists in firestore I get the log message with appropriate data but when it doesn't I get the following exception and I can't find a way to get to use DocumentSnapshot.exists():
java.lang.IllegalStateException: This document doesn't exist. Use DocumentSnapshot.exists() to check whether the document exists before accessing its fields.
Can anyone help me understand what I am doing wrong ?
Thanks a million ! :)

The object returned by get() is a DocumentSnapshot not the document itself. The DocumentSnapshot is never null. Use the exists() method to determine if the snapshot contains a document. If exists() is true, you can
safely use one of the getXXX() methods (in your case, getData() for a map) to obtain the value of the document.
#Override
public void onComplete(#NonNull Task<DocumentSnapshot> task) {
if (task.isSuccessful()) {
DocumentSnapshot snapshot = task.getResult();
if (snapshot.exists()) {
Log.d(LOG_TAG, "DocumentSnapshot data: " + snapshot.getData());
} else {
Log.d(LOG_TAG, "No such document");
}
} else {
Log.d(LOG_TAG, "get failed with ", task.getException());
}
}