Add a template-based form rendering system

[Carl Meyer]

This was accepted as a GSoC project for 2011, and the work was done by Gregor Müllegger. There were ​extensive discussions on the django-developers mailing list about the API.

This ticket is to track the remaining work to get this template-based form rendering API into trunk. The most recent code is at ​https://github.com/carljm/django/compare/master...soc2011%2Fform-rendering - that branch also contains code for #15667 and #16921.

I expect that of those three tickets, #16921 can be merged first, then #15667, and this one last.

The primary issue that still needs to be resolved on this ticket, as well as #15667, is performance. ​https://github.com/carljm/formrenderbench can help with setting up benchmarks.

[Tim Graham]

Carl, it looks like the branch linked above doesn't exist anymore? Do we need to start from scratch on this?

[Carl Meyer]

Hi Tim, a few thoughts:

1. The code that was in that GSoC branch was eventually merged into ​django-floppyforms and has seen updates there since, so I think it would be best to approach this in terms of a new Django branch copying/merging the desired code from floppyforms.

2. I think that #15667 (rendering widgets via templates) alone addresses 90+% of the issues people have with customizing markup in Django forms. I think that ticket is much higher priority than this one, presuming the performance issues can be addressed, or the performance cost is deemed acceptable.

3. Once we have #15667, there are two additional steps that could be taken to resolve this ticket: either a) a straightforward port of the existing .as_ul() and .as_p() methods to render via an overridable template instead of by constructing HTML in Python, or b) a full integration of the extensively customizable form-layouts system that Gregor built for GSoC. To be honest, I am not sure the latter needs to be in Django, I think it works just fine as a third-party add-on (at least until/unless that third-party add-on proves itself as a de facto necessity a la South, which I don't think it has done yet). So I would be in favor of limiting the scope of this ticket to (a), and only even worrying about that once #15667 is fixed.

[Asif Saifuddin Auvi]

As template based widget rendering is now supported, what need to be done to complete this ticket? adjust code from floppy forms?