Accessing data from Django model

Question

Let's say I have a model defined as such

class BlogPost(Models.Model):
    """ Defines a blog model """
    blog    = models.TextField()
    blog_id = models.AutoField(primary_key=True)
    author  = models.CharField()

I want to define some method that accesses the blog posts of a certain author, say 'john doe'. How would I go about defining a method to access all of the blog posts owned by john doe, and then put their blog_id's into a python list?

def selectPostsByUser(user):
""" Implement function to select all object """

NOTE: please disregard the poor representation of the data fields. They are purely arbitrary, I just put names to remove ambiguity from the example.

Aamir Rind · Accepted Answer · 2013-03-29 01:32:33Z

1

I hope you have a Foreign Key to user in your model:

def selectPostsByUser(user):
    return self.objects.filter(user__id=user.id).values_list('blog_id', flat=True)

If the user which you are passing to the selectPostsByUser method is the author (and User model object). Then you should have author as a ForiegnKey field in your model.

answered Mar 29, 2013 at 1:32

Aamir Rind

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Aamir Rind Over a year ago

yes __ is intentional and that is how field lookups works. See here

catherine · Accepted Answer · 2013-03-29 01:58:13Z

1

models.py

class BlogPost(Models.Model):
    """ Defines a blog model """
    blog    = models.TextField()
    blog_id = models.AutoField(primary_key=True)
    author  = models.CharField()

    @classmethod
    def selectPostsByUser(cls, user):
        return cls.objects.filter(author=user)

views.py

user = "john doe"
blogs = BlogPost.selectPostsByUser(user)

answered Mar 29, 2013 at 1:58

catherine

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Comments

Thomas Orozco · Accepted Answer · 2013-03-29 01:42:03Z

0

Your author field should be a ForeignKey, not a CharField. This is how you represent relationships in Django.

Django then allows you to retrieve the post objects associated with an user: user.blog_set.all(). From there, it is trivial to extract the IDs.

Also, Django automatically provides an id field for objects, you don't need to define your own blog_id field.

Following the Django "polls" tutorial should give you all the tools you need to build your app.

edited Mar 29, 2013 at 1:42

answered Mar 29, 2013 at 1:32

Thomas Orozco

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Nick Siemsen · Accepted Answer · 2013-03-29 06:34:58Z

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To answer this question directly, let's say that the author is actually a 'CharField'. You could just do the following to get all blog posts from 'jane doe' and then put all the IDs into a list....

posts = BlogPost.objects.filter(author='jane doe')
list = []
for items in posts:
    lists.append(items.blog_id)

answered Mar 29, 2013 at 6:34

Nick Siemsen

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