[Python-projects] Using pyLint with Django (or other 3rd party libraries)

[Rogan Creswick]

On Tue, Sep 9, 2008 at 6:52 AM, Emile Anclin <emile.anclin at logilab.fr> wrote:
> It seems to be an open issue; however, I don't know much Django.
> Could you tell us more about your problem ?
> How is "objects" implemented in models.Model ?

I haven't been able to discren from the Django code how objects is
implemented -- Here is a sample of code that uses the class that
provides the objects field, and there is a link to the module code
below -- if someone has a few minutes to take a look, it may help.
(I'm assuming there is something I don't understand about defining
object properties in Django which is making it difficult to find the
definition of objects.)

Example model file:

from django.db import models

class Tag(models.Model):
    name = models.CharField(max_length=500, null=False, unique=True)

    def __unicode__(self):
        return self.name

to get a list of the Tags in the database, you run:

>>> Tag.objects.all()

which returns a QuerySet -- a lazy database statement, essentially,
that has roughly the same interface as a list.

The models.Model class is in this file:
http://code.djangoproject.com/browser/django/trunk/django/db/models/base.py

Thanks!
--Rogan


>
> thanks for your remarks
>
> On Fri, Sep 05, 2008 at 10:07:42AM -0700, Rogan Creswick wrote:
>> First off, I am a "seasoned" developer, but I am new to python,
>> pylint, and django.
>>
>> I would very much like to integrate pylint into the build process for
>> my python projects, but I have run into one show-stopper:  One of the
>> error types that I find extremely useful--:E1101: *%s %r has no %r
>> member*--constantly reports errors when using common django fields,
>> for example:
>>
>> E1101:125:get_user_tags: Class 'Tag' has no 'objects' member
>>
>> which is caused by this code:
>>
>> def get_user_tags(username):
>>    """
>>    Gets all the tags that username has used.
>>
>>    Returns a query set.
>>    """
>>    return Tag.objects.filter(  ## This line triggers the error.
>>        tagownership__users__username__exact=username).distinct()
>>
>> # Here is the Tag class, models.Model is provided by Django:
>> class Tag(models.Model):
>>    """
>>    Model for user-defined strings that help categorize Events on
>>    on a per-user basis.
>>    """
>>    name = models.CharField(max_length=500, null=False, unique=True)
>>
>>    def __unicode__(self):
>>        return self.name
>>
>> I believe this is caused because pyLint is unable to find, and/or
>> incorporate information about the superclasses used by the model
>> classes in my django projects. (Tag, in this case).  I've looked over
>> the tutorial, user manual, and help output for pylint, and I haven't
>> found any way to direct pylint at the django source so that it can
>> identify the fields that are inherited from the superclass objects.
>> (The portions of the user manual that look like they would cover this
>> have not yet been written.)
>>
>> Could someone please let me know what, if anything, I can do to get
>> around this?  I do not consider disabling E1101 to be an option -- it
>> checks for precisely the type of error I'm concerned about, and
>> indeed, if I use an object like a model class when it is *not* a model
>> class, that should be caught!
>>
>> Thank you,
>> Rogan Creswick
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>