CODEWITHSUNDEEP
pythondjangolambda
ApPeL
ApPeL

Reputation: 4911

django lambda and django-activity-stream

I am not familiar with the lambda function itself, and don't really know how to debug this issue.

Django-1.1.2

I am using, django-activity-stream in order to render activity streams for my users. In the documentation for this items it says that you need to pass two lambda functions to incorporate with existing newtworks, such as django-friends(the one I am using)

Here are the functions that need to be pasted into your settings.py file.

ACTIVITY_GET_PEOPLE_I_FOLLOW = lambda user: get_people_i_follow(user)
ACTIVITY_GET_MY_FOLLOWERS = lambda user: get_my_followers(user)

I have done so, but now everytime I try and render the page that makes use of this, I get the following traceback.

Caught NameError while rendering: global name 'get_people_i_follow' is not defined

Although this has been set in my settings...

Your help is much appreciated!

Upvotes: 1

Views: 1250

Answers (3)

John Montgomery
John Montgomery

Reputation: 9058

You need to make sure that the functions get_people_i_follow and get_my_followers are imported into your settings files.

e.g.:


from activity_stream.models import get_people_i_follow, get_my_followers

Lambda is just a shorthand for defining a function so:


ACTIVITY_GET_PEOPLE_I_FOLLOW = lambda user: get_people_i_follow(user)

Is equivalent to:


def activity_get_people_i_follow(user):
    return get_people_i_follow(user)
ACTIVITY_GET_PEOPLE_I_FOLLOW = activity_get_people_i_follow

Which upon reflection means you don't gain a lot in this case. However if you needed to avoid importing those function too early in your settings file (i.e. due to circular import) then you could do:


def activity_get_people_i_follow(user):
    from activity_stream.models import get_people_i_follow
    return get_people_i_follow(user)
ACTIVITY_GET_PEOPLE_I_FOLLOW = activity_get_people_i_follow

and just import the activity stream function as you need it.

UPDATE: looks like defining these settings is a red-herring:

https://github.com/philippWassibauer/django-activity-stream/blob/master/activity_stream/models.py#L133

As you can see these settings are only needed if you are not using the default activity streams. So simply remove them from your settings file.

The seg-fault is probably due to an infinite recursion occurring, as get_people_i_follow calls whatever function is defined by ACTIVITY_GET_PEOPLE_I_FOLLOW, which in this case calls get_people_i_follow again...

Upvotes: 1

jcdyer
jcdyer

Reputation: 19155

Somewhere above where these lambdas are defined, you need to import the names get_people_i_follow and get_my_followers. I'm not familiar with django-activity-stream, but it's probably something like from activity_stream import get_people_i_follow, get_my_follwers.

Lambda is a keyword for creating anonymous functions on the fly, so the meaning of your code is basically the same as if you had written the following.

def ACTIVITY_GET_PEOPLE_I_FOLLOW(user):
    return get_people_i_follow(user)

def ACTIVITY_GET_MY_FOLLOWERS(user):
    return get_my_followers(user)

Upvotes: 1

dgel
dgel

Reputation: 16806

If you are integrating with a pre-existing network I don't believe you're actually supposed to write verbatim:

ACTIVITY_GET_PEOPLE_I_FOLLOW = lambda user: get_people_i_follow(user)
ACTIVITY_GET_MY_FOLLOWERS = lambda user: get_my_followers(user)

I believe the author was just showing an example that ACTIVITY_GET_PEOPLE_I_FOLLOW and ACTIVITY_GET_MY_FOLLOWERS need to be set to a lambda or function that accepts one user argument and returns a list of users. You should probably be looking for something like friends_for_user in django-friends, or writing your own functions to implement this functionality.

get_people_i_follow is indeed defined in activity_stream.models but it is just importing what's defined in settings.py. So if settings.py has ACTIVITY_GET_PEOPLE_I_FOLLOW = lambda user: get_people_i_follow(user) you're going to get a wild and crazy circular import / infinite recursion.

Upvotes: 0

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