Bot framework how to validate date in form flow?

Question

Hi,

 

I am working on Microsoft bot framework where i am developing conversation throgh Form Flow . I want to ask user for 2 dates. I want to perform custom validation logic on date like current date entered by user should be greater than previous date entered by user.

 

 Following is my property for FormFlow

[Prompt("Please enter checkin date")]
 [Pattern(@"^\d{1,2}/\d{1,2}/\d{4}$")]
 public string checkindate { get; set; }

  [Prompt("Please enter checkin date")]
 [Pattern(@"^\d{1,2}/\d{1,2}/\d{4}$")]
 public string checkoutdate { get; set; }

i want to validate checkoutdate should be greater than checkindate. How i can do this in Bot framework.

 

Please help me with your suggestion.

 

Thanks,

Ketan