c# - Web API v2 Filter checking different types for same field -

i have code below in api filter. samplerequester object information form. has property called captcha. works great have other forms have captcha property. , work samplerequester objects. how check object captcha property?

public class validatecaptcha : actionfilterattribute {     public override void onactionexecuting(httpactioncontext actioncontext)     {         var cookiepayload = actioncontext.request.getcookie("mycaptcha");         samplerequester requester = (samplerequester)actioncontext.actionarguments["requester"];         if(cookiepayload !== requester.captcha)         {             actioncontext.response = actioncontext.request.createresponse(httpstatuscode.forbidden);         }      }  } 

if know possible types in advance, can use as operator:

public class validatecaptcha : actionfilterattribute {     public override void onactionexecuting(httpactioncontext actioncontext)     {         var cookiepayload = actioncontext.request.getcookie("mycaptcha");         var requester = actioncontext.actionarguments["requester"] samplerequester;         if (requester != null && cookiepayload == requester.captcha)              return;         requester = actioncontext.actionarguments["requester"] anotherrequester;         if (requester != null && cookiepayload == requester.captcha)              return;          actioncontext.response = actioncontext.request.createresponse(httpstatuscode.forbidden);     } } 

if don't, expect whatever type have property captcha, can use dynamic:

public class validatecaptcha : actionfilterattribute {     public override void onactionexecuting(httpactioncontext actioncontext)     {         var cookiepayload = actioncontext.request.getcookie("mycaptcha");         dynamic requester = actioncontext.actionarguments["requester"];         if (requester != null && cookiepayload == requester.captcha)              return;          actioncontext.response = actioncontext.request.createresponse(httpstatuscode.forbidden);     }  } 

ideally, first option, while making sure requesters implement same interface, can use as interface type.

i wonder, why have captcha value in cookie?