How to delete data from Firestore Database in Flutter

In my last example code on flutter, we went through how to add data to a collection in cloud Firestore.

Use the above link to learn how to add cloud Firestore to your flutter project if you have not done it before.

Since the previous code example and this share similarities, we will focus on flutter code example here rather than going through what we have covered before.

For now, we will focus on how to delete data from Firestore database in flutter.

Create new Flutter Project

In your Visual Studio Code, go to View menu > Command Palette.

In the open dialog, select Flutter. Enter the name of your Flutter project and hit enter key button.

Add dependencies to pubspec.yaml

name: firestore_example
description: A new Flutter project.

# The following defines the version and build number for your application.
# A version number is three numbers separated by dots, like 1.2.43
# followed by an optional build number separated by a +.
# Both the version and the builder number may be overridden in flutter
# build by specifying --build-name and --build-number, respectively.
# Read more about versioning at semver.org.
version: 1.0.0+1

environment:
  sdk: ">=2.0.0-dev.68.0 <3.0.0"

dependencies:
  flutter:
    sdk: flutter

  # The following adds the Cupertino Icons font to your application.
  # Use with the CupertinoIcons class for iOS style icons.
  cupertino_icons: ^0.1.2
  http: 0.12.0
  dio: 2.0.22
  cloud_firestore: ^0.9.0 

  dev_dependencies:
  flutter_test:
    sdk: flutter

# For information on the generic Dart part of this file, see the
# following page: https://www.dartlang.org/tools/pub/pubspec

# The following section is specific to Flutter.
flutter:
  # The following line ensures that the Material Icons font is
  # included with your application, so that you can use the icons in
  # the material Icons class.
  uses-material-design: true

  assets:
    - assets/images/umbrella.png
    - assets/images/dnut.png
    - assets/star_anim.flr

  fonts:
    - family: AvenirNext
      fonts:
        - asset: assets/fonts/AvenirNextLTPro-Regular.otf

  # To add assets to your application, add an assets section, like this:
  # assets:
  #  - images/a_dot_burr.jpeg
  #  - images/a_dot_ham.jpeg
  # An image asset can refer to one or more resolution-specific "variants", see
  # https://flutter.io/assets-and-images/#resolution-aware.
  # For details regarding adding assets from package dependencies, see
  # https://flutter.io/assets-and-images/#from-packages
  # To add custom fonts to your application, add a fonts section here,
  # in this "flutter" section. Each entry in this list should have a
  # "family" key with the font family name, and a "fonts" key with a
  # list giving the asset and other descriptors for the font. For
  #
  # For details regarding fonts from package dependencies,
  # see https://flutter.io/custom-fonts/#from-packages

Create new dart file inside lib folder

Go to your project lib folder and create a new dart file. Give the file a name of your choice.

Let import the Firestore package we added earlier to this class.

import 'package:cloud_firestore/cloud_firestore.dart';

Copy and past the code below inside the class.

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/material.dart';

class DeleteDataFromFireStore extends StatelessWidget {
  final db = Firestore.instance;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text("Delete Data from Firestore")),
      body: ListView(
        padding: EdgeInsets.all(12.0),
        children: <Widget>[
          SizedBox(height: 20.0),
          StreamBuilder<QuerySnapshot>(
              stream: db.collection('info').snapshots(),
              builder: (context, snapshot) {
                if (snapshot.hasData) {
                  return Column(
                    children: snapshot.data.documents.map((doc) {
                      return ListTile(
                        title: Text(doc.data['title']),
                        trailing: IconButton(
                          icon: Icon(Icons.cancel),
                          onPressed: () async {
                            await db
                                .collection('info')
                                .document(doc.documentID)
                                .delete();
                          },
                        ),
                      );
                    }).toList(),
                  );
                } else {
                  return SizedBox();
                }
              }),
        ],
      ),
    );
  }
}

Below is the part of where the actual delete process takes place.

We are using the Firestore instance collection and document methods to obtain a document reference.

Calling delete() method on the document reference deletes the data we are interested in.

db.collection('info').document(doc.documentID).delete();

App entry point (Main.dart)

Open the main.dart file and add the code below

import 'package:flutter/material.dart';
import 'delete_data_from_firestore.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Google SignIn',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
      ),
      home: DeleteDataFromFireStore(),
    );
  }
}

RUN YOUR APP

You can use flutter command to run your app – $ flutter run

If everything goes well, you will see screen similar to the image below in your flutter device.


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