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Learn how to resolve common issues in Flutter app development, particularly when fetching data from the `COVID-19 API`. This guide will guide you through troubleshooting techniques and provide sample code for a functional coronavirus tracking application.
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This video is based on the question https://stackoverflow.com/q/62623351/ asked by the user 'AimanIrfan02' ( https://stackoverflow.com/u/13819535/ ) and on the answer https://stackoverflow.com/a/62624968/ provided by the user 'Sagar Acharya' ( https://stackoverflow.com/u/12000053/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Troubleshooting Your Flutter App: Why Does it Throw Errors When Calling the Coronavirus API?

Creating a coronavirus tracker application can be an exciting project for learning app development with Flutter. However, encountering errors when fetching data from the API can be frustrating. In this post, we will explore common issues that might cause your app to throw errors and provide a detailed solution to help you get back on track.

Understanding the Problem

When building a Flutter app to track COVID-19 statistics, you might face an error each time you attempt to call the API, for example, the COVID-19 API. Users often find that pressing the search button leads to a console output indicating an error, despite the logic appearing correct. Here we will analyze your code and suggest steps to troubleshoot the issue effectively.

Analyzing the Code

In your code snippet, the following are the key components involved:

Fetching Data Function:

[[See Video to Reveal this Text or Code Snippet]]

Data Model:

[[See Video to Reveal this Text or Code Snippet]]

These components are crucial for fetching and processing data, yet the errors indicate that there may be a logic flaw or connectivity issue within your implementation.

Detailed Solution

To resolve issues with your Flutter app when calling the API, follow these organized steps:

1. Check Your API URL

Ensure that the API endpoint you are using is correct. If you hardcoded 'malaysia', consider allowing user input to dynamically fetch data based on the country name entered in a text field.

2. Handle HTTP Response Properly

Make sure to handle the HTTP response correctly. In the code provided, the expected response is 200, which indicates whether the request was successful. You need to decode the JSON properly and convert it into a list of your data model:

[[See Video to Reveal this Text or Code Snippet]]

3. Loading Indicator

Provide feedback to users while the app fetches data. A loading spinner can enhance the user experience:

[[See Video to Reveal this Text or Code Snippet]]

4. Update Widget Building Logic

Modify your widget to display a loading indicator when data fetching is in progress:

[[See Video to Reveal this Text or Code Snippet]]

5. Correct Data Mapping

Ensure the mapping of JSON fields to your model matches the structure of the API response:

[[See Video to Reveal this Text or Code Snippet]]

Sample Adapted Code

Below is a sample code refactoring based on the suggestions mentioned. It includes a dynamic country input and enhanced error handling:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By following the guidance and code refactoring steps outlined in this guide, you can troubleshoot the errors in your Flutter app effectively. Remember to always double-check your API calls, ensure your models are correctly defined, and provide feedback to users during data retrieval. Happy coding, and may your coronavirus tracker application become a success!