Want implement a utility class which methods represent steps in a validation process. Is there a pattern or best practise for that?

Question

Hi,

i want to implement a utility class which methods are internal steps of a validation process. Is there a pattern for this or should i use a totally different approach? Im open for suggestions. (I´m coding in abap but i dont think that is important)

Edit: Its no frontend validation of text, but a check if certain conditions are matched. (The parameter is actually a table. For each row i check if there are conditions matched as an example if there is a valid entry in an other db table.)

Somthing like this:

Class Validator 
{
   private bool flag_error;

   private Step1 ( var a, var b )
   {
     //do somthing ...
   }

   private Step 2 ( var a )
   { 
     //do somthing ...
   }

   private Step 3 ( var c )
   {
     //do somthing ...
   }

   static Check(var a, var b, var c)
   {
    Step1(a, b );
    Step2( a );
    Step3( c );
    return flag_error;
    }
}

Usage:

if (Validator.Check(a,b,c) )
{
 //do good stuff
}
else
{
 //do error handling
};

Answer 1

There is one patten that comes to mind. It is the template pattern

I would make an abstract class with Check implemented as above and the Step methods to be implemented by the concrete classes.

Answer 2

I once wrote a visitor pattern, which worked quite nicely for separating the actual validation from the fields.

Answer 3

Hi,

I use C# attributes for validation purpose. You can find a detailed article here. This helps you to implement validation by configuration over convention. Using this technique your validation routines become highly abstract and reusable.

Answer 4

Design decisions really depend on the details. Will there be multiple validator algorithm implementations? Try a Strategy or Template Method pattern.

If you only need this one class performing these multiple steps, you've already implemented a pattern, Composed Method. Keep it simple. Don't add layers of complexity unless they're truly needed.