Custom field validation error in ASP.NET Core 5.0 MVC

Question

I somewhat can't wrap my head around it.

Lets assume simplest model possible:

public class Model
{
   [Required]
   [MaxLength(128)]
   public string Name {get;set;}
}

If you now use it in form and declare validation, it will work. But default messages are not the most pleasant for average user (Field must be an array of length X etc).

And now comes my question, how to create custom validation error? I have seen one useful topic that I can't find anymore, but they were overriding some function and there was no info provided how to call it.

I'm mostly interested in MaxLength, because for Required you can just set Display, which won't work for MaxLength.

user_14924779 · Answer

If you only want to change the default message try it with

[Required]
[MaxLength(128, ErrorMessage = "YourCustomMessageString")]
public string Name {get;set;}

Custom field validation error in ASP.NET Core 5.0 MVC

1 Answers