I didn't think to check the shell! It is definitely issue 2.
I was able to output:
>>> for tag in post.posttag_set.all(): tag.get_absolute_url()
...
'/blog/footag/'
which is exactly what I expect. (I have one post with the tag "footag")
post = get_object_or_404(Post, tag='footag') returns the error:
FieldError: Cannot resolve keyword 'tag' into field. Choices are: html, id,
posttag, pub_date, slug, title
So I tried:
post = get_object_or_404(Post, posttag='footag') which returned:
ValueError: invalid literal for int() with base 10: 'zzz'
I think a lot of my issues are being caused by my ignorance of how I would
refer to a Post objects tag since they are only related via foreign key.
btw, my templates print the tags perfectly with {% for tag in
post.posttag_set.all %}
so seeing >>> for tag in post.posttag_set.all(): tag.get_absolute_url()
print the tag url exactly came as a surprise to me.
On Sunday, June 24, 2012 9:13:32 PM UTC-4, Russell Keith-Magee wrote:
>
> On Mon, Jun 25, 2012 at 8:40 AM, Matthew Meyer
> <matthewwilliamme...@gmail.com<https://mail.google.com/mail/?view=cm&fs=1&tf=1&source=mailto&to=matthewwilliamme...@gmail.com>>
>
> wrote:
> > Hi all, Django newbie here,
> >
> > I have a simple blog app I am working on and am trying to figure out the
> > best way to create a permalink for tags that I have added for blog
> posts.
> > Basically, my models.py consists of two classes: Post and Tag, which has
> > Post as a foreign key: http://dpaste.org/Ojhh5/
> >
> > I am then trying to access the permalink to the tag using: {{
> > tag.get_absolute_url }}
>
> Hi Matthew,
>
> If {{ tag.get_absolute_url }} isn't rendering anything, once of three
> things must be happening:
>
> 1) get_absolute_url isn't defined. Tag clearly has a get_absolute_url
> method, and there's no typo there, so this isn't the problem.
>
> 2) get_absolute_url is raising an error, or returning None. You can
> check this by putting some debug in the get_absolute_url method, or
> sticking a python debugger breakpoint in the method.
>
> 3) tag isn't a valid variable in the template you're rendering.
>
> In the context you're rendering, tag is a variable in a for loop -- so
> the first think to establish is whether you're iterative over anything
> at all. Are you seeing anything rendered by the for loop, or is it
> just the {{ tag.get_absolute_url }} call that is returning an empty
> string? If it's just get_absolute_url, then the problem is (2);
> otherwise, you need to look into (3).
>
> The other way to debug this -- fire up a Python shell. Django's
> template language silences almost all errors. This is by design, since
> the worst thing you could have in production is error messages leaking
> through to the user. However, the upshot of this is that templates can
> be harder to debug, since there's no difference between "doesn't work"
> and "nothing to print". However, if you fire up a Python shell
> (./manage.py shell), you can interrogate the same API that the
> template is using:
>
> # Do your imports, then...
> # Get the post you want to render
> >>> post = get_object_or_404(Post, tag='my tag')
>
> # Print the list of tags
> >>> print post.posttag_set.all()
>
> # Print the absolute URL for the first tag
> >>> print post.posttag_set.all()[0].get_absolute_url()
>
> If there's an error being raised somewhere, these calls will show you
> the full error trace, rather than silencing the errors.
>
> Hope that helps you debug the problem!
>
> Yours,
> Russ Magee %-)
>
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