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Python Build a Social Network with Flask Takin' Names LoginManager

Welby Obeng
Welby Obeng
20,340 Points
Posted by Welby Obeng
Welby Obeng
20,340 Points

Why do you compare models.User.id == userid? 

#function to use if you need to look up a user
@login_manager.user_loader
def load_user(userid):
  try:
    # get user row with id 
    return models.User.get(models.User.id == userid)
  # if does not exist return none
  except models.DoesNotExist:
    return None

Kenneth Love :

  1. Regarding the code above why do you compare models.User.id == userid in get function? why not return models.User.get(userid)? if userid doesn't exist it will throw models.DoesNotExist exception

  2. regarding def load_user(userid), where in social network app do you use use this function and pass in user id? is it login_user(user) in login function?

1 Answer

Kenneth Love
STAFF
Kenneth Love
Treehouse Guest Teacher
Kenneth Love
Kenneth Love
Treehouse Guest Teacher

I'm gonna answer those backwards.

We don't use load_user, but flask-login does any time we need to check/fetch the current user. So, yes, when we login the user. When we do @login_required. When we do current_user. We have to provide that so flask-login knows how to find our user accounts.

Why do the comparison? Mainly to keep it explicit and uniform through the rest of the code base. We do comparisons everywhere else and there's no harm in doing a comparison here.

Nicolas Hampton
Nicolas Hampton
44,638 Points

Yes, but I was actually wondering why when we do that comparison, it doesn't return a boolean, but the userid we put in. I feel like I'm missing something obvious, but it looks like the get method on the User model would receive the value True from the comparison. That doesn't happen though. Why?

Kenneth Love
Kenneth Love
Treehouse Guest Teacher
Kenneth Love
Kenneth Love
Treehouse Guest Teacher

Nicolas Hampton It doesn't do a comparison there, though. It does it in Peewee's ORM. Peewee is using that comparison to craft its SQL query for the database. Here's a bit more information.

Nicolas Hampton
Nicolas Hampton
44,638 Points

Thank you for that. So it's working similarly to the where method on the same ORM model. Got ya. Databases man, one of my weakest points. Getting there!