ASP.NET Core Web API - DateTime Data Annotations Compare dates?

Question

Hello,

When the request is made, is there a way to compare with data annotations if the start date is smaller than the end date?

Thank you.

public class OrderHistoryRequestDto  
    {  
        [Required(ErrorMessage = "Please add StartDate to the request.")]  
        [DataType(DataType.Date)]  
        public DateTime? StartDate { get; set; }  
        [Required(ErrorMessage = "Please add EndDate to the request.")]  
        [DataType(DataType.Date)]  
        public DateTime? EndDate { get; set; }  
    }  

Answer 1

Write custom validation.

    public class OrderHistoryRequestDto : IValidatableObject  
    {  
        [Required(ErrorMessage = "Please add StartDate to the request.")]  
        [DataType(DataType.Date)]  
        public DateTime? StartDate { get; set; }  
        [Required(ErrorMessage = "Please add EndDate to the request.")]  
        [DataType(DataType.Date)]  
        public DateTime? EndDate { get; set; }  
  
        public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)  
        {  
            if(EndDate.Value <= StartDate.Value)  
            {  
                yield return new ValidationResult("End date must be greater than the start date.", new[] { "EndDate" });  
            }  
        }  
    }  
  

If you want an attribute then write a custom attribute.

There is also the openly published documentation which you can read to figure out if an existing attribute will suit your needs. For example, the compare attribute.

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