Скачать или смотреть How to Fix Asp.Net Core Model Binding Issues After Upgrading to Core 3.0

Discover how to solve the common ASP.Net Core model binding issue when upgrading from 2.2 to 3.0, including key changes and practical solutions.
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How to Fix Asp.Net Core Model Binding Issues After Upgrading to Core 3.0

Upgrading your ASP.NET Core application can often bring exciting new features and improvements. However, it can also lead to unexpected issues, especially when it comes to model binding. If you've recently upgraded your ASP.NET Core Web API project from version 2.2 to 3.0 and are encountering model binding problems with generic models, you're not alone. In this post, we will explore the root of the issue and how you can effectively resolve it.

The Problem: Model Binding Not Working

In your project, you have a generic view model defined as follows:

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

You’ve used this view model in your controllers to handle requests like so:

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

Everything appeared to work correctly until the upgrade to ASP.NET Core 3.0, after which the binding to the Id field stopped functioning as expected.

Identifying the Issue

The issue you're facing is due to the way model binding operates in ASP.NET Core. The framework relies on properties with public getters and setters to bind data from incoming requests to your model classes. In your current setup, Id is declared as a public field, not a property. This is why the model binding is failing after the upgrade.

The Solution: Change Fields to Properties

What You Need to Do

To resolve this issue, you need to modify your model by changing the Id field to a property with a public setter. Update your EntityRequestViewModel like this:

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

Why This Works

Model Binding Mechanism: The model binding in ASP.NET Core looks for public properties to populate data. Fields do not trigger the binding process, which is the core reason why your Id was not being populated.

Public Setter: Having a public setter allows the model binder to update the property value based on the incoming request data.

Further Considerations

If you have other view models extending from EntityRequestViewModel, ensure they also adhere to this property structure for consistency and compatibility.

Review any other models in your project that may be using fields instead of properties to prevent further binding issues.

Conclusion

Upgrading to new versions of frameworks like ASP.NET Core can lead to unforeseen challenges, but understanding how to adapt your code to align with framework changes is crucial. By ensuring that your model binding relies on public properties rather than fields, you can continue to utilize generic models in your Web API effectively.

Keep your codebase updated and maintain an eye on the documentation for potential breaking changes in future upgrades. Happy coding!