Spring MVC keep value of unexposed property model -

i have model class:

public class user{     public string title;     public string username;      /* setter getter here */      public string tostring(){         /* output title , username */     } } 

controller:

@requestmapping("/dummy") public class dummycontroller {     private log = logger.getlogger(this.getclass().getname());      @requestmapping(value="binder")     public string binderinput(model model){          userlogin userinit=userlogin.finduserlogin(1l);         model.addattribute("userlogin",userinit);                        return "binderinput";        }      @requestmapping(value="binderresult")     public string binderresult(@modelattribute("userlogin") userlogin userlogin,bindingresult br){         log.debug("userlogin:"+userlogin);         return "binderresult";       } } 

and views (jspx) binderinput:

<form:form action="dummy/binderresult" method="post" modelattribute="userlogin">     title:<form:input path="title" />     <input type="submit"/> </form:form> 

the dao in userlogin.finduserlogin(1l); return user title 'mr' , username 'smith'. browse localhost:8080/myweb/dummy , views showed 'mr' in title field, , update title 'sir' , submit form.

in binderresult expect see

title:sir, username:smith 

but got

title:sir, username:null 

is there way keep property value(s) dao not edited (for field(s) not showed in jspx view) ?

1. i think of hidden field, username can viewed when looking @ html source , can manipulated think cant solution.

2. i have tried @sessionattribute, thought make sense model keeped in session , spring modelattribute fill properties received views session model. still same, title change sir username null.

3. i read @initbinder , try
   databinder.setallowedfields(new string[]{"title"});
   but not help, filters properties , not keep value of other not allowed fields

i start think have manually this:

    @requestmapping(value="binderresult")     public string binderresult(@modelattribute("userlogin") userlogin userlogin,bindingresult br,httpsession session){         /* after put dao model in session in binderinput */         userlogin userloginsession = session.getattribute("userloginsession");         userloginsession.setusername(userlogin.getusername());                     //further process or save userloginsession         log.debug("userlogin:"+userloginsession);         return "dummy/binderresult";         } 

there way keep not edited property in spring expect in first place?

help!

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code 2nd point, asked gouki:

@requestmapping("/dummy") @sessionattributes({"usersession"}) public class dummy2controller {     private log = logger.getlogger(this.getclass().getname());      @requestmapping(value="binder")     public string binderinput(model model,httpsession session){          userlogin userinit=userlogin.finduserlogin(1l);         model.addattribute("usersession",userinit);                      return "binderinput";        }      @requestmapping(value="binderresult")     public string binderresult(@modelattribute userlogin usersession,bindingresult br,httpsession session){         log.debug("usersession:"+usersession);         //further process or save usersession db         return "binderresult";       } } 

and change modelattribute usersession in views:

<form:form action="dummy/binderresult" method="post" modelattribute="usersession">

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problem solved
link read related accepted answer in question:

1. springsource docs
2. stackoverflow explanation @christopher yang
3. captain debug's blog

you can add method, populate object before invocation of every controller method:

@modelattribute("userlogin") public userlogin getuserlogin() {     return userlogin.finduserlogin(1l); } 

after loading changed fields submitted form override old values , in controller you'll have refreshed object.