Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

Python Build a Social Network with Flask How to Win Friends Relationship Model

igsm '
igsm '
10,440 Points
Posted by igsm '
igsm '
10,440 Points

Was a trailing comma forgotten in index setting?

Kenneth Love, I read in peewee docs that we need to add a trailing comma if tuple of indexes contains only one item. I believe we forgot that in the video or was that intentional? Anyway, what's the use of that ?

indexes = (
    (('from_user', 'to_user'), True),
)

1 Answer

Dave Leigh
Dave Leigh
8,640 Points

I noticed in the video for this stage that Kenneth Love was getting the same error I was when I tried to run the app after making the changes:

  File "app.py", line 157, in <module>                                                                                                                                                                                                                                                        
    models.initialize()                                                                                                                                                                                                                                                                       
  File "/home/treehouse/workspace/models.py", line 86, in initialize                                                                                                                                                                                                                          
    DATABASE.create_tables([User, Post, Relationship], safe=True)                                                                                                                                                                                                                             
  File "/usr/local/pyenv/versions/3.4.1/lib/python3.4/site-packages/peewee.py", line 2863, in create_tables                                                                                                                                                                                   
    create_model_tables(models, fail_silently=safe)                                                                                                                                                                                                                                           
  File "/usr/local/pyenv/versions/3.4.1/lib/python3.4/site-packages/peewee.py", line 3871, in create_model_tables                                                                                                                                                                             
    m.create_table(**create_table_kwargs)                                                                                                                                                                                                                                                     
  File "/usr/local/pyenv/versions/3.4.1/lib/python3.4/site-packages/peewee.py", line 3628, in create_table                                                                                                                                                                                    
    cls._create_indexes()                                                                                                                                                                                                                                                                     
  File "/usr/local/pyenv/versions/3.4.1/lib/python3.4/site-packages/peewee.py", line 3652, in _create_indexes                                                                                                                                                                                 
    db.create_index(cls, fields, unique)                                                                                                                                                                                                                                                      
  File "/usr/local/pyenv/versions/3.4.1/lib/python3.4/site-packages/peewee.py", line 2869, in create_index                                                                                                                                                                                    
    'or tuple: "%s"' % fields)                                                                                                                                                                                                                                                                
ValueError: Fields passed to "create_index" must be a list or tuple: "from_user"

This error appears to have been resolved by the start of the "Follow and Unfollow Buttons" video. After adding the trailing comma as Igor suggested, the error disappeared.

Thanks!