Custom Validation Attributes: Comparing two properties in the same model

Question

Is there a way to create a custom attribute in ASP.NET Core to validate if one date property is less than other date property in a model using ValidationAttribute<

Answer 1

I created a library with the most common custom validations in ASP.NET Core. The library also has the client-side validation for all the server-side custom validations. The library solves OP's problem with a single attribute as follows:

// If you want the StartDate to be smaller than the EndDate:
[CompareTo(nameof(EndDate), ComparisionType.SmallerThan)] 
public DateTime StartDate { get; set; }

Here is the GitHub link of the library: AspNetCore.CustomValidation

Currently, the library contains the following validation attributes:

1. FileAttribute - To validate file type, file max size, file min size;

2. MaxAgeAttribute - To validate maximum age against date of birth value of DateTime type;

3. MinAgeAttribute - To validate minimum required age against a date of birth value of DateTime type;

4. MaxDateAttribute -To set max value validation for a DateTime field;

5. MinDateAttribute - To set min value validation for a DateTime field;

6. CompareToAttibute – To compare one property value against another property value;

7. TinyMceRequiredAttribute -To enforce required validation attribute on the online text editors like TinyMCE, CkEditor, etc.