Why Does My Array Populate on Rebuild But Not on Page Refresh? Here’s What You Need to Know!

Discover the common pitfalls in Vue.js that lead to arrays not populating on page refresh. Get expert tips on ensuring reactivity in your data fetching processes using Fetch and Pinia.
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Why Does My Array Populate on Rebuild But Not on Page Refresh? Here’s What You Need to Know!

If you’re a developer using Vue.js with the Composition API, you may have run into a frustrating scenario where your data arrays populate correctly during a rebuild but appear empty upon a page refresh. This issue can be confusing, especially when other parts of your application seem to function normally. In this post, we’ll explore potential reasons behind this behavior and provide actionable solutions to ensure your arrays are reactive and populated correctly, even after refreshing the page.

The Problem: Empty Arrays on Page Refresh

You may find that data fetched from your SQL backend via a .NET 6 API isn’t displaying as expected after a page reload. Specifically, your getAdminUsers method appears to populate the array correctly when changes are made, but once the page is refreshed, the array returns as empty.

Example: The Scenario

Here’s a recap of the relevant code you've implemented:

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

Upon executing the getAdminUsers method after refreshing, instead of seeing the populated array, you encounter:

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

Understanding the Solution: Ensuring Reactivity

The key to solving this issue lies in understanding reactivity in Vue. Reactive properties are designed to automatically update the UI when their state changes. Here are some possible causes of the problem and how to resolve them:

1. Verify Reactive Assignments

The first step is ensuring that you handle your data in a way that retains its reactive properties. If you are assigning your array to a new variable, verify that this variable is also reactive. Use the computed property to establish a reactive link.

Example: Implementing Reactive Variables

Instead of directly using values from your store, utilize computed properties:

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

This ensures that any changes made to the adminUsers within the store will automatically reflect in your UI.

2. Debugging Your Fetch Logic

Make sure your fetch function executes as expected on every page load. Here are a few things to check:

Network Calls: Use browser developer tools to monitor network responses for your fetch call.

Error Handling: Implement error handling to catch any issues that arise while fetching data.

State Management: Ensure that when data is fetched, you correctly update your Pinia store state so that the changes propagate throughout your app.

3. Hot Reload vs. Page Load

The issue could stem from a difference in the environment when refreshing the page versus when hot reloading code during development. Hot reloading maintains application state, while a full page refresh initializes the app from scratch.

Conclusion

In summary, if your arrays populate only when you rebuild the application, but not on a page refresh, the root of the problem often lies in how state and reactivity are managed within Vue.js. By ensuring that your data is adequately reactive and that you are managing your state properly, you can ensure that your arrays populate as expected upon each refresh.

If you’re still struggling, consider revisiting how you're structuring your Pinia store and how you're consuming that data in your components. Reactivity in Vue is a foundational concept; once you grasp this, you’ll unravel many issues like this one.

Have you encountered similar challenges in your Vue.js applications? Share your experiences and tips in the comments below!