Need a way to generate slugs for media entries, etc

[Christopher Allan Webber]

We need to be able to generate URL slugs for media entries.

I'd really like to use
`http://flask.pocoo.org/snippets/5/ <http://flask.pocoo.org/snippets/5/>`_
but have to clear it with the FSF that that public domain assertion
is okay for our codebase and to merge.

Regardless, we need to generate slugs for each entry anyway.
Probably during the submission phase after setting the title there
should be an entry.generate\_slug() method which sets the slug on
the MediaEntry instance.

This way we have a nice way of accessing for example the fictional
address:

[http://mediagoblin.example.org/\ :sub:`cwebber/w/a-walk-in-the-park/](http://mediagoblin.example.org/`\ cwebber/w/a-walk-in-the-park/)

that last bit of the URL being the entry slug.

[Christopher Allan Webber]

Brett Smith says this is fine, we can incorporate :)

If someone has time, this would be a great bitesized task.


-  add necessary dependencies to setup.py if necessary, run
   ./bin/buildout should pull them in if using such a setup
-  put the snippet'ed utility into mediagoblin/util.py
-  add some unit tests in mediagoblin/tests/test\_util.py
-  add a MediaEntry.generate\_slug() method which should generate a
   slug and assign that slug to itself (self['slug'])
-  call MediaEntry.generate\_slug() after title is assigned in the
   submit process and before save

[Aaron Williamson]

0001-Patch-for-Feature-306.patch

[Aaron Williamson]

Made an effort at plucking this low-hanging fruit as described
above. One concern though: if a user names several images "A walk
in the park" (which seems quite possible) they will all have
identical slugs. Should we account for this with some sort of
iterator or other device?

[Christopher Allan Webber]

Great, Aaron!

I think the best thing to do if such a conflict occurs is maybe to
either not generate a slug (hmmm) or tack a uuid onto the name
(hmmmmm)?

[Aaron Williamson]

One way I've solved this in the past is to query the database for
items with identical slugs submitted by the same user. If there is
one, add "-1" (or "-2", etc.) to the end of the slug. However, this
assumes you only want slugs to be unique to users. If you want to
use slugs in other contexts (e.g. sets of photos) this might be an
inadequate solution. It also is probably slower than using a UUID,
because it requires a database hit. (Hmmmmm?)

[Christopher Allan Webber]

Yeah I think numbered slugs are just simply impossible with
mongodb.

Aaron, what do you think of tacking on the entry id of the
MediaEntry if there's a conflict? Conflicts will probably be rare
and it probably won't look **too** bad. Prepending it like
:math:`${id}-$`{slug} probably works. Or the reverse. I think I
like the former though. Thoughts? More useful than a uuid.

[Aaron Williamson]

Yeah, that's a good idea. Or possibly even :math:`${id}/$`{slug}?
Or would that break url patterns?

[Christopher Allan Webber]

It might break the urlpatterns... I'd much rather use a dash.

Here's some pedantic styling comments, thought this looks like a
great start:

::

            'slug':unicode,

do:

::

            'slug': unicode,
    
    
    
        def generate_slug(self):
            self['slug'] = util.slugify(self['title'])

This looks good. Could you add a docstring? It's probably a good
idea that you didn't .save() here, good call.

You might want to add a second argument to util.slugify which is
self['\_id'].

Also, your unit test could really use some examples of non-ascii
characters, for example on the snippet linked above there is the
"u" to "ue".

Aside from this and the conflict resolution we've been discussing,
this patch looks great, like everything I hoped! Make that id
addition change and we can merge this.

[Aaron Williamson]

slug-patch.txt

[Aaron Williamson]

Addressed all of Chris's concerns. Decided to do the dupe-checking
in generate\_slug instead of slugify. Added a couple of tests for
unicode characters.

[Christopher Allan Webber]

Could you use git format-patch? If you do that it'll keep
information about this commit being done by you and etc. Looks good
though.

[Aaron Williamson]

0003-Added-one-more-unicode-test-for-slugify.patch

[Aaron Williamson]

Sure, sorry -- I'm not all that familiar with format-patch and I
was trying to get all of this to you in a single patch file, but I
guess that's unnecessary. Here are all of the applicable patches.

[Christopher Allan Webber]

Nice job, Aaron! Merged and pushed. :)

[Will Kahn-Greene]

The original url for this bug was ​http://bugs.foocorp.net/issues/306 .