**Course Title:** Mastering Dart: From Fundamentals to Flutter Development **Section Title:** Working with APIs and Networking **Topic:** Handling API errors and response management **Overview** In this topic, we will explore how to handle API errors and manage responses in a Dart and Flutter application. We will cover the following key concepts: * Understanding API errors and responses * Handling API errors using try-catch blocks * Parsing API responses using JSON * Using the `http` package to handle API errors and responses * Best practices for handling API errors and responses **Understanding API Errors and Responses** When making API requests, there are several types of errors that can occur: * **HTTP errors**: These are errors that occur when the server returns an HTTP status code that indicates an error, such as 404 (Not Found) or 500 (Internal Server Error). * **JSON parsing errors**: These are errors that occur when the API returns a JSON response that cannot be parsed into a valid Dart object. * **Network errors**: These are errors that occur when the network connection is lost or there is a problem with the network. To handle these errors, we need to use try-catch blocks to catch the exceptions that are thrown when an error occurs. **Handling API Errors using Try-Catch Blocks** Here is an example of how to handle API errors using try-catch blocks: ```dart import 'package:http/http.dart' as http; void main() async { try { final response = await http.get(Uri.parse('https://api.example.com/data')); if (response.statusCode == 200) { final jsonData = jsonDecode(response.body); print(jsonData); } else { print('Error: ${response.statusCode}'); } } catch (e) { print('Error: $e'); } } ``` In this example, we use a try-catch block to catch any exceptions that are thrown when making the API request. If an exception is thrown, we print the error message. **Parsing API Responses using JSON** To parse API responses using JSON, we can use the `jsonDecode` function from the `dart:convert` library. Here is an example: ```dart import 'dart:convert'; void main() { final jsonData = '{"name": "John", "age": 30}'; final data = jsonDecode(jsonData); print(data['name']); // prints "John" print(data['age']); // prints 30 } ``` In this example, we use the `jsonDecode` function to parse the JSON string into a Dart object. **Using the `http` Package to Handle API Errors and Responses** The `http` package provides a simple way to make HTTP requests and handle API errors and responses. Here is an example: ```dart import 'package:http/http.dart' as http; void main() async { try { final response = await http.get(Uri.parse('https://api.example.com/data')); if (response.statusCode == 200) { final jsonData = jsonDecode(response.body); print(jsonData); } else { print('Error: ${response.statusCode}'); } } catch (e) { print('Error: $e'); } } ``` In this example, we use the `http` package to make an HTTP request to the API and handle any errors that occur. **Best Practices for Handling API Errors and Responses** Here are several best practices for handling API errors and responses: * **Use try-catch blocks to catch exceptions**: Use try-catch blocks to catch any exceptions that are thrown when making API requests. * **Handle HTTP errors**: Handle HTTP errors by checking the status code of the response and taking appropriate action. * **Parse JSON responses**: Parse JSON responses using the `jsonDecode` function from the `dart:convert` library. * **Use the `http` package**: Use the `http` package to make HTTP requests and handle API errors and responses. By following these best practices, you can write robust and reliable code that handles API errors and responses effectively. **Conclusion** In this topic, we have covered how to handle API errors and manage responses in a Dart and Flutter application. We have discussed the following key concepts: * Understanding API errors and responses * Handling API errors using try-catch blocks * Parsing API responses using JSON * Using the `http` package to handle API errors and responses * Best practices for handling API errors and responses By following these concepts and best practices, you can write robust and reliable code that handles API errors and responses effectively. **Exercise** Write a Dart program that makes an HTTP request to the API and handles any errors that occur. Use try-catch blocks to catch any exceptions that are thrown and handle HTTP errors by checking the status code of the response. **Solution** Here is an example solution: ```dart import 'package:http/http.dart' as http; void main() async { try { final response = await http.get(Uri.parse('https://api.example.com/data')); if (response.statusCode == 200) { final jsonData = jsonDecode(response.body); print(jsonData); } else { print('Error: ${response.statusCode}'); } } catch (e) { print('Error: $e'); } } ``` Note: This is just an example solution and you should modify it to fit your specific use case. **Leave a comment or ask for help** If you have any questions or need help with this topic, please leave a comment below.