A clean way to use required value types in ASP.NET Core

Thomas — Sun, 17 Sep 2023 16:07:08 +0000

How do you deal with required value types in input models without having to make all of them nullable?

For a long time, the only solutions out there suggested:

Using [BindRequired], which doesn't work for body data.
Using something like [Range], which only works for integers and only if they cannot be zero.
Just making all your properties nullable, which is ugly.

But you can actually get your input models looking like this by making a custom value provider & model binder:

record InputModel
{
    [Required(ErrorMessage = "Optional custom error")]
    public int NonNullableInteger { get; init; }
}

The entire tutorial is kept updated on my blog, alongside source code and an example project: https://thom.ee/blog/clean-way-to-use-required-value-types-in-asp-net-core/

Forem: Thomas