[web2py] empty field saved as NULL or ' '

I have the flowing two field definitions: Field('code_1', default='', label=T("Code 1"), requires=[IS_EMPTY_OR(IS_NOT_IN_DB(db, 'product.code_1',error_message=T('Code 1 already in use'),ignore_common_filters=False)),IS_LENGTH(maxsize=15)]), Field('code_2', default='',label=T("Code 2")), However

[web2py] empty field

how come i have to test an empty string field within a try|except block like this: try: b = q.create_lecture_foldername!=None except: b = False if b: something instead of the more straight forward: if (q.create_lecture_foldername!=None): something because if i try the previous simp

[web2py] empty field crud.update(db.table)

I am using the Pengoworks auto complete plugin. In my model file I have: db.address.city.widget=lambda self,value:INPUT(_type='text',_id='city',_class='ac_input',_name='city_name',requires=self.requires) In web2py_ajax.html: jQuery('#city').autocomplete('/cms/handlers/cityAC',{maxItemsToShow: