I still have other problem, if I have in model db.define_table('task', Field('title',length=128), ...... Field('man_in_charge',db.person,default=db.person.id,writable=True,readable=True), Field('description','text'), ) in controller, grid.fields = ['task.title','man_in_charge'] I got error as followings, if I move away man_in_charge in grid fields, it's ok. Traceback (most recent call last): File "D:\web2py cookbook\web2py\gluon\restricted.py", line 173, in restricted exec ccode in environment File "D:/web2py cookbook/web2py/applications/nano/controllers/default.py", line 659, in File "D:\web2py cookbook\web2py\gluon\globals.py", line 96, in self._caller = lambda f: f() File "D:\web2py cookbook\web2py\gluon\tools.py", line 1652, in f return action(*a, **b) File "D:/web2py cookbook/web2py/applications/nano/controllers/default.py", line 391, in list_task return dict(grid=grid(),person=person,form=form) File "D:\web2py cookbook\web2py\applications\nano\modules\webgrid.py", line 442, in __call__ r = row._extra[colname] File "D:\web2py cookbook\web2py\gluon\sql.py", line 664, in __getattr__ return dict.__getitem__(self,key) KeyError: '_extra' thanks for your advice