Pinia Crash Course #9 - Async Actions (part 2)

Summary

In this video, the instructor demonstrates how to implement asynchronous operations for managing tasks in a task management application. The video focuses on three main actions: adding tasks, deleting tasks, and toggling the 'favorite' status of tasks. These actions are performed asynchronously to update the JSON file, ensuring that data changes persist even after a page refresh. The instructor walks through the process of sending POST, DELETE, and PATCH requests to modify the tasks in the JSON file and handles errors gracefully. By the end of the video, users will have learned how to persist task data across page reloads while ensuring smooth user interactions.

Takeaways

• 😀 The initial lesson involved creating an asynchronous task to fetch tasks and display a loading message during the process.
• 😀 After refreshing the page, the initial data loads again, but changes like deleting or toggling favorites aren't persisted in the JSON file.
• 😀 The goal is to make actions like deleting tasks and toggling favorites asynchronous to persist changes in the JSON file.
• 😀 This persistence will ensure that when the page is refreshed, the updated data from the JSON file is displayed.
• 😀 The script adds 'async' before functions to handle asynchronous tasks for adding, deleting, and toggling tasks.
• 😀 For the add task function, a POST request is sent to add the new task to the JSON file. The task is sent in JSON format.
• 😀 The delete task function sends a DELETE request to remove the task based on its ID, and the endpoint is updated accordingly.
• 😀 The toggle favorite function sends a PATCH request to update the 'is fave' property of a task in the JSON file.
• 😀 Error handling is implemented, and any errors during these asynchronous tasks are logged to the console.
• 😀 After making changes, the page can be refreshed, and the changes (deletion or toggling favorites) are now persisted and displayed correctly.

Q & A

Why do we need to make the actions of deleting a task and toggling a favorite asynchronous?

We need to make these actions asynchronous because they update the JSON file, which is used to persist the changes. Without async operations, these changes wouldn't be saved after a page refresh, causing the state to reset.

What is the role of the `Json.stringify()` function in the async operations?

The `Json.stringify()` function is used to convert JavaScript objects (like the task data) into a JSON-formatted string before sending them in the request body. This ensures that the server can understand and process the data correctly.

What HTTP methods are used in the asynchronous functions, and why?

The HTTP methods used are POST, DELETE, and PATCH. POST is used to add a new task, DELETE is used to remove a task, and PATCH is used to update the favorite status of a task.

What is the purpose of the `headers` in the fetch requests?

The `headers` define the content type of the data being sent. For example, 'Content-Type': 'application/json' tells the server that the body of the request contains JSON data.

Why is it necessary to include the task ID in the URL for DELETE and PATCH requests?

The task ID is necessary to identify which specific task needs to be deleted or updated. It ensures that the correct task is targeted for these actions.

How is error handling implemented in the async functions?

Error handling is implemented by checking if the response is not successful (i.e., `response.ok` is false). If an error occurs, a message is logged to the console to help debug the issue.

What is the significance of using `await` in the async functions?

`await` pauses the execution of the function until the asynchronous operation (e.g., fetching data) is completed. This ensures that tasks are updated on the server before the app proceeds with any further actions.

What happens when you refresh the page after making changes to the tasks (like deleting or favoriting a task)?

After the page refreshes, the changes persist because the data has been updated in the JSON file. This ensures that the modified task list is reloaded, showing the updated state.

What is the expected behavior after a task is added, deleted, or its favorite status is toggled?

After a task is added, deleted, or its favorite status is toggled, the changes are reflected in the JSON file. When the page is refreshed, the new state is fetched, and the updated data is displayed.

How does the code ensure that the task data is updated correctly in the JSON file?

The code makes a request to the appropriate endpoint (POST, DELETE, or PATCH) with the updated task data. These requests modify the JSON file on the server, ensuring that any changes (like adding, deleting, or updating tasks) are persisted.