Packages in Dart

How to Use a Package

Now let's see how we can use a package for our dart project. To use a dart project, we need to do the following:

1. First of all, create a pubspec.yaml file, which contains the dependencies and other metadata.
2. Use the dart pub get command to download your package’s dependencies.
3. Now, if your current dart code uses the features of any dependency, import that dependency into your code.

Creating a pubsec file

A pubspec.yaml is a file that is the top directory of your dart application,

Example:

name: dart_app

dependencies:
  http: ^0.13.4
  test: ^1.21.0

The above lines define the packages js and intl, along with its version.

Getting the Package

Running the command dart pub get downloads the dependency to your application, but you have to run the command at the top of your application directory. 

$ dart pub get

If your app requires a published package, it will fetch it from the pub.dev website. Pub clones the Git repository for a Git-dependent package. Also included are transitive dependencies. If any package depends on the third package, the pub will also download that third package.

Let’s also discuss some of the important pub commands:

Importing the Package

If you want to use any library from the package you have downloaded in your code, you must import the library from the package.

import 'package:http/http.dart' as http;

import 'package:test/test.dart';

After importing the packages, you can use all the features provided by the package.
Example: In this example, we will be importing a package and using its properties.
Code:

// Importing the package to use its functionalities.
import 'package:characters/characters.dart';

void main() {
  var str = 'Hi Ninja';
  print('String: $str');
  print('');

  // Length.
  print('Length: ${str.length}');
  // Using the character.length property.
  print('Characters.length: ${str.characters.length}');
  print('');

  // First character.
  print('The string starts with: ${str.substring(0,1)}');
  // Using the characters.first property.
  print('The First character: ${str.characters.first}');
  print('');

  // Skip last character.
  print('Substring: "${str.substring(0, str.length - 1)}"');
  // Using the character.skipLast method.
  print('Skipping the last character: "${str.characters.skipLast(1)}"');
  print('');

  // Replace characters.
  var newStr = str.characters.replaceAll('Ninja'.characters, 'Great Ninja'.characters);
  print('New String: "$newStr"');
}

Output:

String: Hi Ninja

Length: 8
Characters.length: 8

The string starts with: H
The First character: H

Substring: "Hi Ninj"
Skipping the last character: "Hi Ninj"

New String: "Hi Great Ninja"

Frequently Asked Questions

What is the work of a package manager?

A package manager, sometimes known as a package management system, is a collection of software tools that automate the process of installing, upgrading, customizing, and deleting computer programs on a consistent basis.

Is it possible to upgrade the package's version in our project?

Yes, we can easily upgrade the version of our packages using the dart pub upgrade command. This command upgrades all the dependencies in your project. If you want to upgrade a specific dependency, you can specify its name, e.g. dart pub upgrade name. 

What is a pub tool and at what places it is used?

The pub is a Dart package manager with reusable libraries and packages for Flutter, AngularDart, and standard Dart apps.

Conclusion

This article thoroughly discussed the packages in dart and how to use them. We discussed how to declare the package in the pubspec.yaml file, then get the package using the dart pub get command and import the file to use its functions.

We hope that this blog helped you enrich your knowledge regarding packages in Dart. We can use the concepts of dart in building an android app to learn in-depth about android development. Check out our Android Development course on the Coding Ninjas website. Do upvote our blog to help other ninjas grow.
Happy Coding!