New URL tag for reversing urls with placeholder args/kwargs

[h.a.clifford@…]

It would be incredibly useful if Django supported a placeholder url tag:

usage would be similar to url, but with args/kwargs that don't match the url regex.

E.g: {% urlplaceholder User username='<%username%>' %}, where my url rule only allows a-z usernames.
(Currently, you can't do this).

This isn't a huge change which is why I'm suggesting it (line 325 urlresolves does the regex check after substituting in the values)

Why is this useful? It would allow *easy* generation of javascript templates on the frontend - all the current methods seem to involve reversing the urls with javasacript which is hardly in keeping DRY.

Example:

<script id='UserTemplate' type='jqueryTemplate'>
<a href='{% urlplaceholder User username='<%username%>' %}'>
<img src='{% get_media_url %}/user.png'>
</a>
</script>

[Aymeric Augustin]

I wouldn't dismiss the regex check so quickly. Currently, there's a guarantee that an URL generated with reverse will be resolved correctly. While I understand your reasons to drop this guarantee, we can't do this lightly.

Note that if #16362 was committed, it would rely on the regex check after substituting the values. Those two tickets are incompatible.

You could use a something like r'/users/(?:<% )(\w+)(?: %>)' or r'/users/(\w+|<% \w+ %>)' in your URLconf — sure, it's a hack.

EDIT: while working on this, I missed the fact that the ticket suggested a new tag, not a modification of the existing tag. Please disregard the comment above. Still, it's DDN.

[Jannis Leidel]

This sounds like a great idea for a 3rd party app, that would provide helpers for JavaScript development.