How to get back an attribute of Resource in tastypie

How to get back an attribute of Resource in tastypie

Details :
@localhost:8000/api/v1/user/1/
Gives :
{
"date_joined": "2013-08-28T04:20:36.704342",
"email": "a@a.com",
"first_name": "",
"id": 1,
"is_active": true,
"is_staff": true,
"is_superuser": true,
"last_login": "2013-08-29T01:18:07.163345",
"last_name": "",
"password":
"pbkdf2_sha256$10000$EVKt9xEHWSaD$S/ipn3mqoSMBjo98D9wconcloape1eFvsu9mVoIm+KA=",
"resource_uri": "/api/v1/user/1/",
"username": "admin"
}
Now if i wanna get only firstname How can i do that in tasty pie??