class ChangePhoneSerializer(serializers.Serializer):
'''
Change my phone number
'''
password_current=serializers.CharField(max_length=16,allow_blank=False,required=True)
new_phone=serializers.CharField(max_length=13,required=True,allow_blank=False)

def __init__(self,*args,**kwargs):
    self.user=kwargs.pop('user')


def validate(self,data):
    phone=data['new_phone']
    pwd_current=data['password_current']

    errmsg=''
    if not pwd_current:
        errmsg=str(_('Current password must be given'))
    else:
        if not self.user.check_password(pwd_current):
            errmsg=_('Current password is incorrect')


    if errmsg:
        raise serializers.ValidationError(errmsg)

    return data

data=request.data
    serializer=ChangePhoneSerializer(user=request.user,data=data)
    if serializer.is_valid():
      #do stuff to change the phone