python - Related name already in use by another Foreign key -

i've created small sqlite3 database using peewee try understand foreign keys , them working in simple database.

from peewee import *  db = sqlitedatabase('database.db')   class category(model):     category = charfield()      class meta:         database = db   class subcat(model):     description = blobfield()     sub_cat = charfield()     top_category = foreignkeyfield(category, related_name='group')      class meta:         database = db  db.connect() db.create_tables([category, subcat], safe=true) 

i have created controller.py file handle database transactions. (updated) peewee import * database import *

class modcat(category):      def add_cat(self,category):         update = category.create(category=category)      def get_cat(self):         categories = category.select(category.category).order_by(category.category)         return categories  class modsubcat(subcat):      def save_sub_cat(self, sub, master, desc):         name = category().select().where(category.name==master)         update = subcat.create(sub_cat=sub, top_category=name, description=desc) 

finally, main.py allows me enter data database simple form created in wxformbuilder.

from gui import * controller import *  class menu(indb):     def __init__(self, parent):         indb.__init__(self, parent)         get_categories = modcat()         list = get_categories.get_cat()         new_list = []         thing in list:             new_list.append(thing.category)         print new_list         f in new_list:             self.m_combobox1.append(f)       def click_save( self, event ):         new_cat = modcat()         new_cat.add_cat(self.m_textctrl3.getvalue())         self.getparent()  # assigns parent frame frame.         self.close()  # closes frame removing main menu.         frame = menu(none)         frame.centre()         frame.show()      def sub_save( self, event ):         sub = self.m_textctrl5.getvalue()         master = self.m_combobox1.getvalue()         desc = "hi"         update = modsubcat()         update.save_sub_cat(sub, master, desc)   #start app calling sub class of mainmenu if __name__ == '__main__':     app = wx.app(0)     frame = menu(none)     frame.centre()     frame.show()     app.mainloop() 

the database creates no errors when run main.py returns error.

    traceback (most recent call last):   file "c:/users/********/pycharmprojects/rams/main.py", line 2, in <module>     controller import *   file "c:\users\********\pycharmprojects\rams\controller.py", line 13, in <module>     class modsubcat(subcat):   file "c:\python27\lib\site-packages\peewee.py", line 4710, in __new__     field.add_to_class(cls, name)   file "c:\python27\lib\site-packages\peewee.py", line 1437, in add_to_class     invalid('the related_name of %(field)s ("%(backref)s") '   file "c:\python27\lib\site-packages\peewee.py", line 1431, in invalid     raise attributeerror(msg % context) attributeerror: related_name of modsubcat.top_category ("group") in use foreign key. 

i've changed related_by value no luck. fact have sub class modsubcat in controller.py causing problem?

ive removed related_name='group'

from top_category = foreignkeyfield(category, related_name='group') , works.

what related_name for?