Andorid how can i add value inside of Documents array - android

i try to add a Map item to a certain position of my Array. To do so i tried this code:
String userid =FirebaseAuth.getInstance().getCurrentUser().getUid();
DocumentReference washingtonRef = db.collection("Users").document(userid);
// Atomically add a new region to the "regions" array field.
washingtonRef.update("shoppingLists[0]", FieldValue.arrayUnion("greater_virginia"));
}
Here is the structure where i have to add a value:
At this point i have to add the value

You can't index into array fields like this with Firestore. You can add or remove elements of an list type field by value using arrayUnion and arrayRemove, but you can't specify where that item is in the array. If you need more control over the order of the elements in the array, you will have to read the document first, modify the array in memory, then update that field back into the document.

Related

How can i create and update an array of number in firestore?

I want to create an array programmatically in firestore. Also, I want to update the array as shown in the image attached.
I want to store all reference Numbers in this array. And whenever there is a new reference number, I want to update the array. Please help.
This is what I have tried. I know it's wrong. It's not updating the array rather replacing it.
Map<String, Object> mapone= new HashMap<>();
Map<String, Object> maptwo = new HashMap<>();
mapone.put("Refnum", f_refrenceNum);
maptwo.put("RefNumber", mapone);
upiRefnum.set(maptwo,SetOptions.merge());
Your code is telling Firestore to the RefNumber.Refnum fields with the values you specify for is.
If you want to add f_refrenceNum to the array, you can use an array-union operation:
mapone.put("Refnum", FieldValue.arrayUnion(f_refrenceNum));
This will add f_refrenceNum if it isn't already in the array. If it is already in the array and you want to add a duplicate, you will have to read the document into your application code, add the number in your application code, and then write the entire array back to the database.
See the Firestore documentation on adding items to an array.

How to append an array into an array field in firestore?

Question
I have a collection named Users with a field named friendEmails which is an array that contains Strings.
I have a document with friendEmails = {joe#gmail.com, dan#gmail.com}, and I want to append newEmails = {mat#gmail.com, sharon#gmail.com} to it.
Problem
The only options I know for this are:
Reading the friendEmails array first, then adding the union of it and newEmails to the document.
Iterating over the elements of newEmails (let's and each iteration doing:
myCurrentDocumentReference.update(FieldValue.arrayUnion, singleStringElement);
(Since FieldValue.arrayUnion only lets me pass comma-separated elements, and all I have is an array of elements).
These two options aren't good since the first requires an unnecessary read operation (unnecessary since FireStore seems to "know" how to append items to arrays), and the second requires many write operations.
The solution I'm looking for
I'd expect Firestore to give me the option to append an entire array, and not just single elements.
Something like this:
ArrayList<String> newEmails = Arrays.asList("mat#gmail.com", "sharon#gmail.com");
void appendNewArray() {
FirebaseFirestore firestore = FirebaseFirestore.getInstance();
firestore.collection("Users").document("userID").update("friendEmails", FieldValue.arrayUnion(newEmails));
}
Am I missing something? Wouldn't this be a sensible operation to expect?
How else could I go about performing this action, without all the unnecessary read/write operations?
Thanks!
You can add multiple items to an array field like this using FieldValue.arrayUnion() as the value of a field update:
docRef.update("friendEmails", FieldValue.arrayUnion(email1, email2));
If you need to convert an ArrayList to an array for use with varargs arguments:
docRef.update("friendEmails", FieldValue.arrayUnion(
newEmails.toArray(new String[newEmails.size()])
));

How to read array data from the firestore using kotlin?

I am new in android development and when I read array data from firestore using following code
val variable = arrayOf(document.get("restaurant"))
and then loop over the variable using code
varibale.forEach {
Log.d("someTag", ${it.toString()} + " is your data")
}
I get the result with square brackets at log as following
[somedata, somedata2] is your data
my problem is that forEach loop runs only once and I am not able to get the result (without square brackets) as following
somedata is your data
somedata2 is your data
I have 2 elements in my restaurant array in firestore
I will be very thankfull to any one who will help me.
You are actually wrapping an array/list into another array when using arrayOf, that's why you see those brackets. Instead, try casting your document.get("restaurant") and then looping directly through it.
arrayOf doesn't parse an array. It creates a new array using the elements you pass to it. That's not what you want. You should instead cast document.get("restaurant") to the type that you expect to get from Firestore.
If a field is an array of strings, then the SDK will give you a List<*>, and you will need to make sure each item in the list is a String, if that's what you stored in the array.
val variable = document.get("restaurant") as List<*>
// Iterate variable here, make sure to check or convert items to strings

How to retrieve last element from firestore Array in android?

I have a schema like below in firestore:
I have document snapshot listener written to fetch the whole array via:
// inside snapshot listener
List<String> order_data= (List<String>) documentSnapshot.get("done"); // this returning whole array!
But i want only last element from the done array. Any help people?
If you want any data in a document, you have to read the entire document. There is no avoiding that.
If you already have the contents of a list field in a List object, then you can get the list item in that list using:
String last = order_data.get(order_data.size() - 1);

Make Score History in Array Field Firestore

How to make history score in Array
I try u make score in array like this
this my firestore
And this is my code
String uid = auth.getCurrentUser().getUid();
muridref.document(uid).update("nilai", FieldValue.arrayUnion(skortampil));
When I get the same score the array field doesn't make new Array data,
without see data there or not in array
As mentioned in the documentation Update elements in an array about this behavior:
If your document contains an array field, you can use arrayUnion() and arrayRemove() to add and remove elements. arrayUnion() adds elements to an array but only elements not already present.
Considering that, it's working as expected, since it's not adding values that are equal. So, this means that you won't be able to add values that are equal using the method arrayUnion() directly.
This other question from the Community - accessible here - indicates that for you to achieve this goal, you will need to read all the values from the array in your client side, update your values in the array outside the database and then, writing/updating it back in the database.
Let me know if the information helped you!

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