add method in firebase firestore code example

Example 1: firebase functions add to database

import * as functions from 'firebase-functions';
import * as admin from 'firebase-admin';
admin.initializeApp(functions.config().firebase);

exports.onMsgAdded = functions.database.ref('/users/{uid}/messages/{to_uid}/{msg}').onCreate((snap, context) =>{
    const data = snap.val();
    const msgRoot = admin.database().ref('/users/' + context.params.to_uid + '/messages/' + context.params.uid);
    return msgRoot.set(data);
});

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);
            }
        });