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Creating Rails like template helpers in Django

Submitted by Richard on Thu, 06/24/2010 - 22:01

I wanted to make some easy link helpers so that I could have customized rounded corner links without needing JS and so that I could change them easily later if I needed to. This is so easy in Rails it is just crazy trivial. This was not the case in Django, and even though I believe it should be easier (and I believe it is easier with a little help with a method here and there). I tried to do it the real way. By making a custom tag.

First the Rails way, just add the following to application_helper.rb

def blue_link(url, text)
  "<span class='blue-link'><a href='#{url}'>#{text}</a></span>"
end

Then add to your template

<%= blue_link(new_user_path, "Sign Up Here!") %>

This is so easy it is crazy!, now for the Djano one, hold your breath! I wanted to add the following style of tag to my template,

{% bluelink 'Sign up here' %}{% url project.users.views.create %}{% endlink %}

Seems like it should be easy enough right? First I added an 'extras' app to handle my extra bits and pieces -make sure you include your '__init__.py', within that app I created a directory 'templatetags' which also contains our main tag file 'helper_tags.py' with that directory also containing a '__init__.py' file. I also needed to add 'project.extras' to INSTALLED_APPS in my 'settings.py'

Here is what I have in my 'helper_tags.py'

from django import template

class BlueLinkNode(template.Node):
  def __init__(self, text, url):
    self.text = text
    self.url = url
  def render(self, context):
    return '<span class="blue-link"><a href="'+ self.url.render(context) + '">'+ self.text + '</a></span>'

def do_bluelink(parser, token):
    url = parser.parse(('endlink',))
    parser.delete_first_token()
    text = token.split_contents()[1][1:-1]
    return BlueLinkNode(text, url)
    
register = template.Library()
register.tag('bluelink', do_bluelink)

Now if I add

{% load helper_tags %}

To my template I can finally use my helper tag.

Although creating a helper like the above frustrated the hell out of me, and the syntax was so sensitive to every include and move. There is still so much that I love about Django which makes me want to carry on using it as one of my main development tools. But I think we can learn from the simplistic beauty of Ruby on Rails. Saying that I am a relative newbie to Python/Django and would love your feedback. If there is an obvious easier way to do this please get back to me!.

Tags:

The right way...

Submitted by GuillaumeCisco (not verified) on Thu, 01/26/2012 - 17:59.

You could just use :

in your template :
{% url project.users.views.create as the_url %}
{{ the_url|bluelink:"Sign up here" }}

in your .py
@register.filter
def bluelink(value, arg):
    return '<span class="blue-link"><a href="%s">%s</a></span>' % (value, arg);

Please read the docs.
Thanks.

Thanks for the suggestion,

Submitted by Richard on Wed, 02/01/2012 - 23:15.

Thanks for the suggestion, but I personally don't like adding hard coded html inside of python methods. It feels a little dirty and is harder to maintain.

Shorter and more elegant way,

Submitted by Fantomas42 (not verified) on Thu, 01/26/2012 - 19:39.

Shorter and more elegant way, without Python code. ::

{% url project.users.views.create as the_url %}
{% include "my_blue_link_template.html" %}

my_blue_link_template.html ::

{{ the_url }}

Unfortunately you can then

Submitted by Richard on Wed, 02/01/2012 - 23:14.

Unfortunately you can then not place in business logic that maybe needed to process the output further.

Ahem.

Submitted by Bob (not verified) on Tue, 10/05/2010 - 01:11.

Why the hell would you want a templatetag to generate some span tag? Come on, please take another example, you just took a bazooka to kill a mosquito here.

Generally playing with {% if %} and/or some filters is enough for such a simple case…

Yes I agree that is my point!

Submitted by Richard on Tue, 10/05/2010 - 17:29.

If you can do it easily and simply great, but you can't. In Rails you can do it so simply.

I was wanting to make a quick helper method to add an extra span for links with round corners which may change in future. If I want to go and change all of the tags that have {% if %} etc wrapped around them then that is a big pain in the arse.

Not being able to add simple tags easily in Django is a big downfall of the framework. Which is why Roger even suggested using a different framework.

What I was really fishing for was an easier way of doing this...

Thanks for the feedback though....

web2py

Submitted by Anonymous (not verified) on Fri, 07/30/2010 - 08:33.

You might like web2py with its (to me) easier layout.

Roger, thanks for the tip, I

Submitted by Richard on Mon, 08/02/2010 - 13:51.

Roger, thanks for the tip, I will look into that!

I was also going to check out turbo gears at some point, but any advice is appreciated!

Cheers

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