**Course Title:** Mastering Dart: From Fundamentals to Flutter Development **Section Title:** Working with APIs and Networking **Topic:** Using the `http` package to make network calls **Introduction** In this topic, we will explore how to use the `http` package to make network calls in Dart and Flutter. The `http` package is a popular and widely-used package for making HTTP requests in Dart. We will cover the basics of using the `http` package, including how to make GET, POST, PUT, and DELETE requests, as well as how to handle errors and responses. **Installing the `http` package** Before we can use the `http` package, we need to install it. You can install the `http` package using the following command: ```bash dart pub add http ``` **Importing the `http` package** To use the `http` package, we need to import it in our Dart file. We can do this by adding the following line at the top of our file: ```dart import 'package:http/http.dart' as http; ``` **Making a GET request** To make a GET request using the `http` package, we can use the `get` function. Here is an example of how to make a GET request to the JSONPlaceholder API: ```dart void main() async { final response = await http.get(Uri.parse('https://jsonplaceholder.typicode.com/posts')); if (response.statusCode == 200) { final jsonData = jsonDecode(response.body); print(jsonData); } else { print('Failed to load data'); } } ``` In this example, we are making a GET request to the JSONPlaceholder API and printing the response data to the console. **Making a POST request** To make a POST request using the `http` package, we can use the `post` function. Here is an example of how to make a POST request to the JSONPlaceholder API: ```dart void main() async { final response = await http.post(Uri.parse('https://jsonplaceholder.typicode.com/posts'), headers: { 'Content-Type': 'application/json', }, body: jsonEncode({ 'title': 'New Post', 'body': 'This is a new post', 'userId': 1, }), ); if (response.statusCode == 201) { final jsonData = jsonDecode(response.body); print(jsonData); } else { print('Failed to create new post'); } } ``` In this example, we are making a POST request to the JSONPlaceholder API and printing the response data to the console. **Making a PUT request** To make a PUT request using the `http` package, we can use the `put` function. Here is an example of how to make a PUT request to the JSONPlaceholder API: ```dart void main() async { final response = await http.put(Uri.parse('https://jsonplaceholder.typicode.com/posts/1'), headers: { 'Content-Type': 'application/json', }, body: jsonEncode({ 'title': 'Updated Post', 'body': 'This is an updated post', 'userId': 1, }), ); if (response.statusCode == 200) { final jsonData = jsonDecode(response.body); print(jsonData); } else { print('Failed to update post'); } } ``` In this example, we are making a PUT request to the JSONPlaceholder API and printing the response data to the console. **Making a DELETE request** To make a DELETE request using the `http` package, we can use the `delete` function. Here is an example of how to make a DELETE request to the JSONPlaceholder API: ```dart void main() async { final response = await http.delete(Uri.parse('https://jsonplaceholder.typicode.com/posts/1')); if (response.statusCode == 200) { print('Post deleted successfully'); } else { print('Failed to delete post'); } } ``` In this example, we are making a DELETE request to the JSONPlaceholder API and printing a success message to the console. **Handling errors** To handle errors when making network calls using the `http` package, we can use a try-catch block. Here is an example of how to handle errors when making a GET request: ```dart void main() async { try { final response = await http.get(Uri.parse('https://jsonplaceholder.typicode.com/posts')); if (response.statusCode == 200) { final jsonData = jsonDecode(response.body); print(jsonData); } else { print('Failed to load data'); } } catch (e) { print('Error: $e'); } } ``` In this example, we are catching any errors that occur when making the GET request and printing the error message to the console. **Conclusion** In this topic, we have covered how to use the `http` package to make network calls in Dart and Flutter. We have covered how to make GET, POST, PUT, and DELETE requests, as well as how to handle errors and responses. We have also covered how to install and import the `http` package, and how to use try-catch blocks to handle errors. **Practice Exercise** Try making a GET request to the JSONPlaceholder API using the `http` package. Print the response data to the console. **Leave a comment** If you have any questions or need help with the practice exercise, please leave a comment below. **External Resources** * [http package documentation](https://pub.dev/packages/http) * [JSONPlaceholder API documentation](https://jsonplaceholder.typicode.com/)