Part 8 – Add & Retrieve Multiple Documents

[embedyt] https://www.youtube.com/watch?v=Bh0h_ZhX-Qg[/embedyt]

In part 8 of the Firestore tutorial we replace our DocumentReferences’ set method for the CollectionReference’s add method to add more than one document into our Notebook collection. Instead of giving each document a name, Firestore will auto generate a random ID for them.
We will retrieve all documents from the collection and display them in our app. For this we will use the get method as well as the SnapshotListener’s onEvent method again. Instead of a single DocumentSnapshot we will get a QuerySnapshot that contains multiple QueryDocumentSnapshots. As before we can call toObject on a DocumentSnapshot to turn it into an object of our custom Java class.
We will also retrieve our auto generated random id from this DocumentSnapshot by calling getId on it and then save it in a field of our note object, which we exclude from the Firestore database with the @Exclude annotation to avoid redundant data.

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Links & DependenciesNote.javaactivity_main.xmlMainActivity.java

Firebase setup guide with dependencies and console link:

firebase.google.com/docs/android/setup

package com.codinginflow.firestoreexampleproject;

import com.google.firebase.firestore.Exclude;

public class Note {
    private String documentId;
    private String title;
    private String description;

    public Note() {
        //public no-arg constructor needed
    }

    @Exclude
    public String getDocumentId() {
        return documentId;
    }

    public void setDocumentId(String documentId) {
        this.documentId = documentId;
    }

    public Note(String title, String description) {
        this.title = title;
        this.description = description;
    }

    public String getTitle() {
        return title;
    }

    public String getDescription() {
        return description;
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp"
    tools:context="com.codinginflow.firestoreexampleproject.MainActivity">

    <EditText
        android:id="@+id/edit_text_title"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Title"
        android:inputType="text" />

    <EditText
        android:id="@+id/edit_text_description"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Description"
        android:inputType="text" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="addNote"
        android:text="Add" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="loadNotes"
        android:text="Load" />

    <android.support.v4.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <TextView
            android:id="@+id/text_view_data"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="20sp" />

    </android.support.v4.widget.NestedScrollView>
</LinearLayout>

package com.codinginflow.firestoreexampleproject;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;

import com.google.android.gms.tasks.OnSuccessListener;
import com.google.firebase.firestore.CollectionReference;
import com.google.firebase.firestore.DocumentReference;
import com.google.firebase.firestore.EventListener;
import com.google.firebase.firestore.FirebaseFirestore;
import com.google.firebase.firestore.FirebaseFirestoreException;
import com.google.firebase.firestore.QueryDocumentSnapshot;
import com.google.firebase.firestore.QuerySnapshot;

public class MainActivity extends AppCompatActivity {
    private static final String TAG = "MainActivity";

    private static final String KEY_TITLE = "title";
    private static final String KEY_DESCRIPTION = "description";

    private EditText editTextTitle;
    private EditText editTextDescription;
    private TextView textViewData;

    private FirebaseFirestore db = FirebaseFirestore.getInstance();
    private CollectionReference notebookRef = db.collection("Notebook");
    private DocumentReference noteRef = db.document("Notebook/My First Note");

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        editTextTitle = findViewById(R.id.edit_text_title);
        editTextDescription = findViewById(R.id.edit_text_description);
        textViewData = findViewById(R.id.text_view_data);
    }

    @Override
    protected void onStart() {
        super.onStart();
        notebookRef.addSnapshotListener(this, new EventListener<QuerySnapshot>() {
            @Override
            public void onEvent(QuerySnapshot queryDocumentSnapshots, FirebaseFirestoreException e) {
                if (e != null) {
                    return;
                }

                String data = "";

                for (QueryDocumentSnapshot documentSnapshot : queryDocumentSnapshots) {
                    Note note = documentSnapshot.toObject(Note.class);
                    note.setDocumentId(documentSnapshot.getId());

                    String documentId = note.getDocumentId();
                    String title = note.getTitle();
                    String description = note.getDescription();

                    data += "ID: " + documentId
                            + "\nTitle: " + title + "\nDescription: " + description + "\n\n";
                }

                textViewData.setText(data);
            }
        });
    }

    public void addNote(View v) {
        String title = editTextTitle.getText().toString();
        String description = editTextDescription.getText().toString();

        Note note = new Note(title, description);

        notebookRef.add(note);
    }

    public void loadNotes(View v) {
        notebookRef.get()
                .addOnSuccessListener(new OnSuccessListener<QuerySnapshot>() {
                    @Override
                    public void onSuccess(QuerySnapshot queryDocumentSnapshots) {
                        String data = "";

                        for (QueryDocumentSnapshot documentSnapshot : queryDocumentSnapshots) {
                            Note note = documentSnapshot.toObject(Note.class);
                            note.setDocumentId(documentSnapshot.getId());

                            String documentId = note.getDocumentId();
                            String title = note.getTitle();
                            String description = note.getDescription();

                            data += "ID: " + documentId
                                    + "\nTitle: " + title + "\nDescription: " + description + "\n\n";
                        }

                        textViewData.setText(data);
                    }
                });
    }
}