How to Access a Method from Razor File in Blazor Server

Discover how to effectively call methods from Razor files in Blazor Server applications and troubleshoot common errors.
---

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Access a method from razor file in Blazor Server

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
How to Access a Method from Razor File in Blazor Server: A Complete Guide

Blazor Server is a powerful framework that allows developers to build interactive web applications using C-. However, many developers face challenges when trying to access methods defined in Razor components. One common issue arises when attempting to call a method from a Razor file, leading to errors such as "Delegate to an instance method cannot have null 'this'." In this post, we'll explore how to effectively access methods in Blazor Server and fix related issues.

The Problem

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

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

However, you encounter the following error upon loading the view:

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

What Went Wrong?

The error occurs because UpdateInputSVG.UpdateMainDwg is being interpreted incorrectly. Instead of directly referencing the method, it is looking for the method without an instance context. This can be confusing, especially when transitioning from traditional C- event handling to Blazor's event bindings.

The Solution

To resolve the issue, you need to be explicit when binding the TextChanged event. Instead of directly referencing the method, you should use a lambda expression that provides the necessary context for the instance. Here's how to do this:

Step-by-Step Fix

Change the Event Binding: Update the TextChanged attribute to use a lambda expression that properly calls the method within its context.

Update your MudTextField definition as follows:

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

Understand Lambda Expressions: By using @((value) => UpdateInputSVG.UpdateMainDwg()), you're creating a delegate that points to the UpdateMainDwg method while also ensuring it’s called in the context of the correct instance. This approach is often necessary in Blazor because it uses EventCallback<T> instead of just standard delegates like Action<T>.

Why It Works

Using a lambda expression allows Blazor to correctly interpret the context in which UpdateMainDwg exists, preventing the null reference error. This adjustment is crucial for Blazor's event system, which handles event callbacks differently than traditional C- UI frameworks.

Conclusion

Working with methods in Razor files in Blazor Server can sometimes be tricky, especially when navigating through specific instance contexts. By following the steps outlined above and using lambda expressions for event binding, you can ensure that your methods are called correctly without encountering common errors.

If you found this guide useful, feel free to share it with others who might be facing similar challenges in their Blazor applications!