asp.net mvc - MVC 5.0 <Format Exception> -

in mvc application "twentyfifth", model :

public class student {         public string studentname { get; set; }         public int studentid { get; set; }         public string fathername { get; set; }     } 

a method support-class in same project :

public void editsupport(int id, student std2)         {              sqlconnection con = new sqlconnection("data source=my;initial catalog=db;integrated security=true");              sqlcommand com = new sqlcommand("update studentt set studentname='"+ std2.studentname + "', fathername='" + std2.fathername + "' studentid=" + id + "", con);              con.open();             com.executenonquery();         } 

and finally, controller goes :

[httppost]         [actionname("edit")]         public actionresult edit_post(int id, formcollection formcollector)         {                         student std = new student();              std.studentid = id;             std.studentname = formcollector["studentname"].tostring();             std.fathername = formcollector["fathername"].tostring();              bussinessndatalayer bl = new bussinessndatalayer();              bl.editsupport(id, std);              return redirecttoaction("index");         } 

question : why there format exception when change controller ->

std.studentid = convert.toint32(formcollector["studentid"]); 

note : @ break point found string value in std.studentid comma(,) reply.

the default model binder handle of you. try changing code model binder conversion you:

public actionresult edit_post(int id, formcollection formcollector, int studentid) {     ...     std.studentid = studentid;     ... } 

it best practice never access form collection directly , use typed viewmodels , action method params instead.