Скачать или смотреть How to Pass Parameters to an EventHandler in WebView2

Learn how to modify an EventHandler in WebView2 to pass additional parameters effortlessly, enhancing your implementation of Edge functionality in C# .
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How to Pass Parameters to an EventHandler in WebView2: A Simple Guide

Working with the WebView2 control in C# can be challenging, especially if you're trying to pass parameters to an EventHandler. If you've found yourself in a situation where your programming logic necessitates passing a variable into your event methods while navigating, you're not alone. This guide will demystify that process by addressing how to correctly pass a string parameter into an EventHandler and implement a practical solution.

The Problem: EventHandler Signature Limitation

When handling navigation events in WebView2, you might typically set up your event like this:

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In the code above, the InputText method is tied to the NavigationCompleted event of the WebView. However, you may want to pass a parameter (like a string variable) to InputText. The issue arises because the delegate signature of EventHandler<CoreWebView2NavigationCompletedEventArgs> only allows for a specific method signature:

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This means you cannot simply add additional parameters to your method, leading to confusion and frustration in your coding process.

The Solution: Using Lambda Expressions

A practical way to work around the limitations of the EventHandler is to use lambda expressions while still matching the delegate's required signature. Here's how you can achieve that:

1. Modify the Event Subscription

Instead of directly linking the InputText method, you can create a lambda function that matches the required signature. The lambda function can then call InputText with additional parameters. Here’s how you do it:

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2. Update the InputText Method

Your InputText method will need to accommodate the new parameter. Update it like this:

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3. Use String Interpolation

In your updated InputText method, leverage string interpolation. This allows you to insert the test parameter into your JavaScript code dynamically. It makes your code cleaner and more adaptable to changes in the parameter value.

Optional: Ignoring Unused Parameters

If you find that you're not using the sender parameter in your method, you can choose to ignore it explicitly using the discard operator _:

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This implementation helps keep your code clean if you don’t need to interact with the sender object.

Conclusion

Handling events in WebView2 doesn't need to be complicated. With the right approach, you can effectively pass additional parameters into your event handlers. By utilizing lambda expressions and method modifications, you can enhance the functionality of your application in a straightforward manner.

Feel free to share your experiences or any issues you might encounter while working with WebView2 in the comments below. Happy coding!