Validate Property as [Required], but don't validate the value itself. Is it possible with Attributes and conventions in .net core 2 or higher? - asp.net-core

Question

public class Post {
// ... other properties here
public Author { get; set; }
}
public class Author {
// ... other properties here
public List<Post> Posts { get; set; }
}
This is an overly-simplistic example. What I basically want is that the Author property in the Post class is never null, it MUST have a value. But because I'm pulling Author from a database, I am 100% sure that it's valid, so I want to skip the validation of the value of the Author property's value
In .net core 3 preview 9, recursive validation is causing unnecessarily long hold-ups where join entities for many-to-many relationships are involved.
I assume one workaround is to use [ValidateNever] in conjunction with the Validate() method just to check that the Author is not null. But I don't know if one of them will override the other.
But I am ideally looking to achieve this with Attributes and/or conventions

Answer 1

You could write your custom validation attribute.When the value is null, it returns an Validation error.Otherwise, it returns ValidationResult.Success.
public class CustomRequiredAttribute :ValidationAttribute
{
protected override ValidationResult IsValid(object value, ValidationContext validationContext)
{
if(value != null)
{
return ValidationResult.Success;
}
else
{
var propertyName = validationContext.DisplayName;
var type = validationContext.ObjectType;
return new ValidationResult("Could not be null for " + propertyName);
}
}
}
Model:
public class Post {
// ... other properties here
[CustomRequired]
public Author { get; set; }
}