I am trying to create a query which only selects documents whose reference is equal to a given reference, using Java for Android development. A document which it would match contains the reference for the path "/users/someUser". I am creating the reference like so:
DocumentReference ref = mDatabase.document("users/someUser");
I have also tried:
DocumentReference ref = mDatabase.document("/users/someUser");
Then the query:
Query query = mDatabase.collection("myCollection").whereEqualTo("refField", ref).limit(10);
However, when I run the query and check the task.isSuccessful() in the onComplete method, it's not passing, i.e. it didn't work, whereas when I remove the .whereEqualTo(), it passes and the task's result isn't empty. How can I properly use .whereEqualTo() to check for all documents containing a specific reference?
An example of a document that should match my query would be:
/myCollection/GDpojS5koac2C7YlIqxS which contains the field:
refField: /users/someUser (value of type reference)
And an example of a document that should not match my query would be:
/myCollection/J5ZcVAMYU1nI5XZmh6Bv which contains the field:
refField: /users/wrongUser (value of type reference)
I think you need to add a get() method to run the query and add an onCompletionListener.
Something like this should work:
mDatabase.collection("myCollection")
.whereEqualTo("refField", ref)
.limit(10)
.get()
.addOnCompleteListener({task ->
if(task.isSuccessful){
val result = task.result
})
The above example is in kotlin, but i guess in java it is something similar
You need not to worry about the documents, if you create a query based on your fields then all the documents will be returned in the "QuerySnapshot" object,
for eg,
CollectionReference collectionReference = db.collection(FIRESTORE_USERS);
DocumentReference documentReference = collectionReference.document(userID);
CollectionReference notificationCollection = documentReference.collection(FIRESTORE_NOTIFICATIONS);
notificationCollection.whereEqualTo(USER_TYPE, userType)
.whereGreaterThanOrEqualTo(SEND_AT, calendar.getTime())
.get().addOnSuccessListener(new OnSuccessListener<QuerySnapshot>() {
#Override
public void onSuccess(QuerySnapshot documentSnapshots) {
List<DocumentSnapshot> snapshotsList = documentSnapshots.getDocuments();
ArrayList<NotificationCollections> notificationCollectionsArrayList = new ArrayList<>();
for (DocumentSnapshot snapshot : snapshotsList) {
// each document having that particular field based on query
}
}});
in the above example I am fetching all those documents which match a particular user id and also having time greater than or equal to supplied time (time will not be used in your case)
I hope this helps...
Happy coding :)
Related
In my firestore database,there are 12+ documents.I am getting the first 3 documents correctly by calling the below function on button click. But on the secondclick, though the documentReference is passed correctly, its not retrieving any data.The querySnapshot size is coming 0. What could be the problem.
Given below is the declaration
private val db: FirebaseFirestore = FirebaseFirestore.getInstance()
private val colRef: CollectionReference = db.collection("Notebook")
private var lastResult: DocumentReference? = null
private lateinit var query: Query
and below is the onButtonClick code :
private fun loadNoteNew() {
#Suppress("SENSELESS_COMPARISON", "LiftReturnOrAssignment")
if (lastResult == null) {
query = colRef.orderBy("priority")
.limit(3)
} else {
Log.i(TAG, "Start ${lastResult!!.id}")
query = colRef.orderBy("priority")
.startAfter(lastResult)
.limit(3)
}
Log.i(TAG, "before get")
query.get()
.addOnSuccessListener { querySnapshot ->
var data = ""
Log.i(TAG, "querySnapshot Size : ${querySnapshot.size()}")
if (lastResult != null) {
Log.i(TAG, "querySnapshot ID : ${lastResult!!.id}")
}
for (snapshot in querySnapshot) {
val note = snapshot.toObject(Note::class.java)
note.id = snapshot.id
val title = note.title
val desc = note.description
val priority = note.priority
data += "${note.id} \nTitle =$title \nDescription = $desc\nPriority : $priority\n\n"
}
if (querySnapshot.size() > 0) {
data += "---------------\n\n"
textView_loadData.append(data)
lastResult = querySnapshot.documents[querySnapshot.size() - 1].reference
Log.i(TAG, lastResult!!.id)
}
}
}
Given below is the logcat for first click
I/FireStoreExample: before get
I/FireStoreExample: querySnapshot Size : 3
I/FireStoreExample: P9hIw4Ai7w4IHP6H3ew3
and given below is the logcat of second click
I/FireStoreExample: Start P9hIw4Ai7w4IHP6H3ew3
I/FireStoreExample: before get
I/FireStoreExample: querySnapshot Size : 0
I/FireStoreExample: querySnapshot ID : P9hIw4Ai7w4IHP6H3ew3
Please help me find out,where i am getting it wrong.
Thanks
The second query result is empty because of a misunderstanding on the semantics of query pagination using startAt and startAfter methods.
Let's say the Notebook collection contains N documents. When you make the first query you're asking for the first 3 documents ordered by the priority field so the query is returning documents 1..3. Then upon the second click you're expecting the query to return the next 3 results so indeed you're expecting documents 4..6. The keypoint here is that both startAt and startAfter paginate based on the value of the ordered field rather than with the last document retrieved. Overall the semantics of startAt and startAfter are roughly as follows.
orderby(X).startAt(Y) => Return documents whose X field is greater than or equal Y
orderby(X).startAfter(Y) => Return documents whose X field is strictly greater than Y
With that in mind, let's examine what the code is actually doing when you make the second query:
// At the end of the first query...
lastResult = querySnapshot.documents[querySnapshot.size() - 1].reference
// Second query
query = colRef.orderBy("priority")
.startAfter(lastResult)
.limit(3)
In the code above you're asking for the documents whose "priority" field is greater than document reference "P9hIw4Ai7w4IHP6H3ew3" and indeed there are no documents greater than that, therefore the result set is empty. Here is api reference for both.
There is yet another thing to note. Because these methods filter upon the fields value the position of the cursor could be ambiguous. For instance, if you have 4 documents with priority 3 and already retrieved the leading three if you set startAfter(3) you'll be missing a document. Similarly, if startAt(3) were to be made you'll get back the same three documents. This is also pointed out in the documentation. All in all you have a couple of options to make this work as intended:
Add another orderby in another field so that documents are uniquely identified by the combination so to prevent any cursor ambiguity and be able to use startAfter with guarantees. Next snippet build upon the doc samples and your code.
// first query
query = colRef.orderBy("priority")
.orderBy("AnotherField")
.limit(3)
// Save last document
lastResult = querySnapshot.documents[querySnapshot.size() - 1]
// Second and next queries
query = colRef.orderBy("priority")
.orderBy("AnotherField")
.startAfter(lastResult)
.limit(3)
Lastly remember that it might be simpler to just query all the documents if they're not many and delay optimizations until they become a performance issue.
where calues not working it does not filter results how i can fix it
here is my database
here is my code
CollectionReference collection = mDB.collection("full_order");
Query query = collection.whereEqualTo("Bakeryid", "1");
query.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
#Override
public void onComplete(#NonNull Task<QuerySnapshot> task) {
if (task.isSuccessful()) {
Log.d("Results", task.getResult().toString());
Toasty.success(getContext(), "Succefuul ", Toasty.LENGTH_LONG).show();
userOrder = task.getResult().toObjects(UserOrder.class);
adapterTruckDrivers = new RecycleViewAdapterTruckDrivers(getContext(), userOrder);
recyclerView.setAdapter(adapterTruckDrivers);
} else {
Log.d("Results", "Errrror");
// Log.d("Results",task.getResult().toString());
Toasty.error(getContext(), "Error ", Toasty.LENGTH_LONG).show();
}
}
});
and i have a quastion
can i use FirebaseDatabase methods like child etc.. when i am using Firestore ?
To solve this, please change the following line of code:
Query query = collection.whereEqualTo("Bakeryid", "1");
to
Query query = collection.whereEqualTo("order.BakeryID", 1);
There are three problems in your code.
The name of the property is BakeryID and not Bakeryid. See lowercase id?
That property is nested under the order Map. You should specify that in your query.
You are passing to the whereEqualTo() one as a String and not as a Number. In your database, the value of that property is not a String. See, it does not contain quotation marks?
i'm not familiar with firestore but you need to query document before referring to next collection, like this
String id = "Tyc...."
CollectionReference collection = mDB.collection("full_order");
Query query =collection.document(id).whereEqualT..
To understand and learn more refer to this link
Change this:
CollectionReference collection = mDB.collection("full_order");
Query query = collection.whereEqualTo("Bakeryid", "1");
into this:
CollectionReference collection = mDB.collection("full_order");
Query query = collection.whereEqualTo("bakeryID", "1");
The attribute inside whereEqualTo should match the one in the database
I'm trying to list documents that matches field String value from ArrayList.
Simply:
I have ArrayList with tags stored at runtime
and documents with field tag
and I want to query documents that matches tag with one of tags stored in ArrayList. Is this possible with official query or does I have to download all documents and filter it client-side? Thanks for any answers.
Also, this is my method generating query:
public static Query getQueryForFollowed(DocumentSnapshot snapshots) {
if (snapshots == null || !snapshots.exists()) {
return FirebaseFirestore.getInstance().collection("posts").whereEqualTo("null", "null"); // return query that will get nothing
}
ArrayList<String> f = processFollowedTags(snapshots);
Query query = FirebaseFirestore.getInstance()
.collection("posts")
.whereEqualTo("tag", f.get(0));
for (int i = 1; i < f.size(); i++) {
query = query.whereEqualTo("tag", f.get(i));
}
return query;
}
I have debugged code and query has contained requested conditions, but query didn't found any document matching it.
Try This
Query query = FirebaseFirestore.getInstance()
.collection("posts")
.whereEqualTo("tag", f.get(0)).orderBy("tag", Query.Direction.ASCENDING);;
After some more search on Google I have found that querying field to multiple values is not available.
According to:
https://stackoverflow.com/a/46633294/8428193
https://github.com/firebase/firebase-js-sdk/issues/321
Below code snippet may help you.
fun arrayContainsQueries() {
// [START array_contains_filter]
val citiesRef = db.collection("cities")
citiesRef.whereArrayContains("regions", "west_coast")
// [END array_contains_filter]
}
ref : git
As of Nov 2019 this is now possible to do with the in query.
With the in query, you can query a specific field for multiple values
(up to 10) in a single query. You do this by passing a list containing
all the values you want to search for, and Cloud Firestore will match
any document whose field equals one of those values.
it would look like this:
Query query = FirebaseFirestore.getInstance()
.collection("posts")
.whereIn("tag", f);
Firestore database image
Hello, I just tried to use Firestore. I had some problem when getting document id.
The question is, I want to get a document id (red box) which has value (blue box) in it.
I use the following query:
collection("mychannel").whereEqualTo("74wRU4xHrcV9oWAXEkKeRNp41c53")
But did not give results.
Thanks!
As in the official documentation:
Although Cloud Firestore can store arrays, it does not support querying array members or updating single array elements.
So there is no way in which you can use the following query:
collection("mychannel").whereEqualTo("74wRU4xHrcV9oWAXEkKeRNp41c53")
If you only want to get the entire userId array you need to iterate over a Map like this:
collection("mychannel").document("1fReXb8pgQvJzFdzpkSy").get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
#Override
public void onComplete(#NonNull Task<DocumentSnapshot> task) {
if (task.isSuccessful()) {
DocumentSnapshot document = task.getResult();
if (document.exists()) {
Map<String, Object> map = document.getData();
for (Map.Entry<String, Object> entry : map.entrySet()) {
if (entry.getKey().equals("userId")) {
Log.d("TAG", entry.getValue().toString());
}
}
}
}
}
});
But note, even if userId object is stored in the database as an array, entry.getValue() returns an ArrayList, not an array.
So the output will be:
[74wRU4xHrcV9oWAXEkKeRNp41c53]
A better approach will be if you consider this alternative database structure, where each user id is the key in a map and all values are true:
userId: {
"74wRU4xHrcV9oWAXEkKeRNp41c53": true,
"AdwF...": true,
"YsHs...": true
}
This question is answered here: Firestore: Query by item in array of document
In summary, don't use arrays to store data in Firestore as the query you are trying to do is not available yet (remember it is still in beta). You should use a Map instead.
I am doing a query to get an array from Firebase and everything works fine. The query is the following:
FirebaseDatabase.getInstance().getReference()
.child("results").child("mood")
.child(Preferences.getUserId(this))
.addListenerForSingleValueEvent(new ValueEventListener() {
...
And I noticed the child() chain always returns a DatabaseReference object. However, I wanted to use limitToLast() to get only the last element of this array. I didn't really understand why but it returns a Query instead of a DatabaseReference, but both have the addListenerForSingleValueEvent() method since DbRef extends Query.
FirebaseDatabase.getInstance().getReference()
.child("results").child("mood")
.child(Preferences.getUserId(this))
.limitToLast(1)
.addListenerForSingleValueEvent(new ValueEventListener() {
The problem is that it's not parsing my response as it was with DbRef, and then I get an exception:
com.google.firebase.database.DatabaseException: Expected a List while deserializing, but got a class java.util.HashMap
I looked into the HashMap and it's just a Map of my Object attributes as Strings but not parsed.
Why do Query and DatabaseReference have a different response/deserialization method?
Any help is greatly appreciated.
EDIT: As per requested, that it the code to get the data. It's the same for both cases.
#Override
public void onDataChange(DataSnapshot snapshot) {
GenericTypeIndicator<List<Mood>> t = new GenericTypeIndicator<List<Mood>>() {};
moodList = snapshot.getValue(t);
...do stuff with moodList
Whereas moodList is a List<Mood>
You didn't post the code for your Mood class or a sample of the JSON that is stored at location "mood". I'm assuming that you have defined Mood as a POJO that satisfies the Firebase requirements for getters/setters and default constructor. Also that the value stored at "mood" is a valid array of Mood elements.
When you modify your query with limitToLast(1), Firebase returns a map containing the last Mood in the array. Perhaps you were expecting it to return a List<Mood> with length of one. I don't find the Firebase documentation clear on this point. Perhaps Firebaser Frank can provide more details.
To see more clearly what is returned with limitToLast(1), you can modify your code like this:
public void onDataChange(DataSnapshot snapshot) {
Map<String,Object> map = (Map<String,Object>) snapshot.getValue();
Log.i(TAG, "onDataChange: map=" + map);
}
The output will look like this, where N is the index for the last value in your array:
onDataChange: map={N={<the fields of your Mood POJO here>}}