Table of contents for Django Development with Djblets
- Django Development with Djblets
- Django Development with Djblets: Custom Tag Helpers
- Django Development with Djblets: Unrooting your URLs
- Django Development with Djblets: Data Grids
- Django Development with Djblets: Dynamic Site Configuration
I’m planning to cover all of what Django can do, but for now, let’s start simple with something most Django developers spend way too much time creating: Custom tags.
Django’s nice enough to provide a @register.simple_tag decorator for creating very basic tags that don’t take a context but do take parameters. This is great, but what if you want more? Many Django applications use the same boilerplate time and time again to create their tags, but we make it much easier.
Introducing @basictag and @blocktag.
Ever wanted to use Django’s @register.simple_tag but needed access to the context? I’ve found far too many cases where this would be useful, but Django doesn’t make this easy. Your tag code would end up looking like this:
class MyTagNode(template.Node): def __init__(self, arg1, arg2): self.arg1 = arg1 self.arg2 = arg2 def render(self, context): arg1 = Variable(self.arg1).resolve(context) arg2 = Variable(self.arg2).resolve(context) return context['user'] @register.tag def mytag(parser, token): bits = token.split_contents() return MyTagNode(bits, bits)
Do this a few times and it’s bound to drive you nuts. How about this instead?
from djblets.util.decorators import basictag @register.tag @basictag(takes_context=True) def mytag(context, arg1, arg2): return context['user']
Far less code and increased readability. Hooray!
@blocktag aims to do the same thing @basictag does but for block tags. A block tag is a tag that contains nested content, like @spaceless or @for. This usually requires even more boilerplate than the above code fragment, except with the added complexity of having to grab the contents of the block.
We’ve condensed it down to this:
from djblets.util.decorators import blocktag @register.tag @blocktag def blinkblock(context, nodelist, arg1, arg2): return "<blink>%s</blink>" % nodelist.render(context)
If you’ve built block tags in the past, you’ll appreciate how simple that was.