firebase save own userdata cloud firestore code example

Example 1: simple firestore cloud function update document

import * as functions from 'firebase-functions';
import * as admin from 'firebase-admin';

admin.initializeApp();

export const resetCounter = functions.https.onRequest((req, res) => {
    const resetRef =  admin.firestore()
    .collection('collectionName')
    .doc('documentName')
    resetRef.get().then((doc) => {
        if(doc.exists){
            resetRef.update({counter: 0})
              .catch(err => {
            console.log("Error",err)
            res.send("500");
          })
       }
    }).catch(err=>{
      	//Internal server error
      	console.log("Error",err)
        res.send("500");
    });
  //Successful operation
  res.send("200");
});

Example 2: android java add new record to Firebase Firestore

Map<String, Object> city = new HashMap<>();
city.put("name", "Los Angeles");
city.put("state", "CA");
city.put("country", "USA");

db.collection("cities").document("LA")
        .set(city)
        .addOnSuccessListener(new OnSuccessListener<Void>() {
            @Override
            public void onSuccess(Void aVoid) {
                Log.d(TAG, "DocumentSnapshot successfully written!");
            }
        })
        .addOnFailureListener(new OnFailureListener() {
            @Override
            public void onFailure(@NonNull Exception e) {
                Log.w(TAG, "Error writing document", e);
            }
        });