How can I handle validation failure messages in ASP.NET Core?

How can I handle validation failure messages in ASP.NET Core?

In ASP.NET Core, you can handle validation failure messages by using the ModelState object. When a model validation fails, the errors are stored in ModelState, which you can then access to display appropriate messages.

Can you show me an example of how to access these messages?

Sure! You can access validation messages in your controller like this: if (!ModelState.IsValid) { var errors = ModelState.Values.SelectMany(v => v.Errors); } This will give you a list of error messages.

What if I want to customize the error messages?

You can customize error messages by using data annotations in your model. For example, you can use [Required(ErrorMessage = "This field is required.")] to specify a custom message.

Is there a way to return these messages in a JSON format?

Yes, you can return validation messages in JSON format by creating a response object that includes the errors and returning it from your action method.