Скачать или смотреть Resolving the StateHasChanged() UI Update Issue in Blazor WASM

Discover how to effectively update your UI in Blazor WebAssembly using `StateHasChanged()` when filtering items.
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This video is based on the question https://stackoverflow.com/q/72309932/ asked by the user 'Scott Perry' ( https://stackoverflow.com/u/13969967/ ) and on the answer https://stackoverflow.com/a/72314731/ provided by the user 'Neil W' ( https://stackoverflow.com/u/2936204/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Resolving the StateHasChanged() UI Update Issue in Blazor WASM

If you're developing an application with Blazor WebAssembly (WASM), you might have come across a frustrating issue where the UI doesn't update as expected even after calling StateHasChanged(). This is particularly common in scenarios where you're filtering input dynamically, such as in a mega menu. If you find yourself needing to click or hit the Enter key to see changes, keep reading as we explore the solution to this problem.

Understanding the Problem

In a typical Blazor application, changes to the UI are supposed to happen automatically when data changes. However, there are situations where you may find the UI remains unchanged despite calling StateHasChanged(). This is primarily due to the binding mechanisms in Blazor and the specific events you are leveraging to trigger updates.

In the scenario described, the problem arises when using the onkeypress event to trigger a UI refresh upon input changes while expecting the input's bound value (filterTerm) to update simultaneously. This leads to a disconnect where StateHasChanged() gets called, but the value of filterTerm remains the same until the input loses focus or the user hits enter.

A Better Approach: Use oninput for Binding

To ensure your UI updates seamlessly as the input changes, you should change your event binding from onkeypress to oninput. The oninput event is triggered every time the value of the input changes, providing a more responsive experience for users. Here’s how you can change your input element:

Updated Input Binding Code:

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

Benefits of This Approach

Responsive Interactions

Immediate Feedback: Users see the updated highlighted text as they type without needing additional clicks or keystrokes.

Simplified Code

Remove Redundant Logic: Since oninput directly updates the bound value, you can eliminate the need for an explicit call to RefreshUI() to invoke StateHasChanged().

Streamlined User Experience

User-Friendly Design: By ensuring the UI updates in real-time, you enhance the overall responsiveness and user engagement of your application.

Conclusion

By implementing the oninput event for your inputs instead of relying on other events like onkeypress, you can effectively resolve the UI update issues associated with StateHasChanged() in your Blazor WebAssembly applications. This not only improves the functionality of your application but also ensures a smoother and more responsive user experience.

If you encounter similar issues in your projects, remember this simple yet powerful switch to enhance your Blazor applications significantly. Happy coding!