Django Templating - More Than Just Blocks

Django Templating More Than Just Blocks Presentation by Christine Cheung
http://www.xtine.net @plaidxtine

Django Templating @ PyCon 2012 by Christine Cheung About the
Presenter Front End Developer President of PyLadies Python Diversity Organization Speaker at DjangoCon 2011 Best Practices for Front End Django Developers

Django Templating @ PyCon 2012 by Christine Cheung What I’m
Going to Talk About Intro to Templating Effective Use of Built-In Tags Extending Templates Template Loading What’s New

Django Templating @ PyCon 2012 by Christine Cheung Django Templating
101 This is the End User Experience Balance between power and ease Design

Django Templating @ PyCon 2012 by Christine Cheung Helpful Tools
Django template theme for your IDE syntax highlighting, autocompletion django-debug-toolbar template paths, session variables Print out tag/ﬁlter reference guide

Django Templating @ PyCon 2012 by Christine Cheung Folder and
File Structure Keep templates in one place

Django Templating @ PyCon 2012 by Christine Cheung Style Guide
Think PEP 8 coding conventions consistent spacing {% load %} all template tags up top try {# comment #} rather than  also, {% comment %} {% endcomment %}

Django Templating @ PyCon 2012 by Christine Cheung The Basics
Start with base.html template <!doctype html> <head> <title>{% block title %}demo{% endblock title %}</title> </head> <body> {% block content %}{% endblock content %} </body> </html>

Django Templating @ PyCon 2012 by Christine Cheung The Basics
Then have pages inherit from it {% extends “base.html” %} {% block title %}the foo page{% endblock title %} {% block content %} <div id=”foo”> this is a bar. </div> {% endblock content %}

Django Templating @ PyCon 2012 by Christine Cheung Common Blocks
I use these in practically every project: title meta_tags, robots extra_head content extra_js

Django Templating @ PyCon 2012 by Christine Cheung Block Practices
End your block structures {% block title %} foo { % endblock title %} instead of {% block title %} foo {% endblock %} Can’t repeat blocks however: context processor, include, custom template tag Don’t “over block”

Django Templating @ PyCon 2012 by Christine Cheung Including Templates
{% include “snippet.html” %} great for repeating template segments I heard you liked includes... don’t include an include in an include

Django Templating @ PyCon 2012 by Christine Cheung Variables Tend
to be objects passed from a view Modify objects with ﬁlters {{ variable|lower }} Loop through them using tags {% if variable %} foo {% else %} bar {% endif %} You can also create your own ﬁlters and tags

Django Templating @ PyCon 2012 by Christine Cheung Security By
default, Django’s security is rather solid on the template side of things... but if you use safe or {% autoescape %} *** make sure you sanitize the data! ***

Django Templating @ PyCon 2012 by Christine Cheung URLs Name
{% url %} tags as much as possible deﬁne URL Pattern in urls.py url(r'^foo/$', foo, name="foo"), <a href=”{% url “foo” %}”>foo</a> ”{{ STATIC_URL }}css/style.css” NOT “/static/css/style.css”

Django Templating @ PyCon 2012 by Christine Cheung Forms For
heavy form action, take a look at: django-ﬂoppyforms (HTML5) django-crispy-forms {% include form.html %} as_ul makes more sense than p or table

Django Templating @ PyCon 2012 by Christine Cheung More Than
One Way...

Django Templating @ PyCon 2012 by Christine Cheung ... to
pick a box There are multiple ways to accomplish the same task No ultimately right or wrong way use what suits you or your team

Django Templating @ PyCon 2012 by Christine Cheung An Example
{% if foo.bar %} {{ foo.bar }} {% else %} {{ foo.baz }} {% endif %} or... {% firstof foo.bar foo.baz %}

Extending Templates

Django Templating @ PyCon 2012 by Christine Cheung Custom Tags
and Filters demo/ models.py templatetags/ __init__.py demo_utils.py views.py {% load demo_utils %}

Django Templating @ PyCon 2012 by Christine Cheung Making a
Custom Filter @register.filter(name='remove') from django import template register = template.Library() @register.filter def lower(value): # lowercased value with no passed arguments return value.lower() {{ foo|lower }} if you always expect a string as ﬁrst argument, use @stringﬁlter def cut(value, argument): # remove passed arguments from value return value.replace(argument, '') {{ foo|remove:"bar" }}

Django Templating @ PyCon 2012 by Christine Cheung Making a
Custom Tag Tags are a bit more complex two steps: compiling and rendering Decide its purpose but start simple

Django Templating @ PyCon 2012 by Christine Cheung A Simple
Example <p> It is now {% current_time "%Y-%m-%d %I:%M %p" %} </p>

Django Templating @ PyCon 2012 by Christine Cheung Simple Tag
from django import template register = template.Library() @register.simple_tag def current_time(format_string): try: return datetime.datetime.now().strftime(str(format_string)) except UnicodeEncodeError: return 'oh noes current time borked'

Django Templating @ PyCon 2012 by Christine Cheung Nodes and
Stuff import datetime from django import template register = template.Library() @register.tag(name="current_time") def do_current_time(parser, token): try: tag_name, format_string = token.split_contents() except ValueError: msg = '%r tag requires a single argument' % token.split_contents()[0] raise template.TemplateSyntaxError(msg) class CurrentTimeNode(template.Node): def __init__(self, format_string): self.format_string = str(format_string) def render(self, context): now = datetime.datetime.now() return now.strftime(self.format_string)

Django Templating @ PyCon 2012 by Christine Cheung Easier Template
Tag Creation django-templatetag-sugar makes it simple to deﬁne syntax for a tag django-classy-tags class based template tags extensible argument parse for less boilerplate

Django Templating @ PyCon 2012 by Christine Cheung DO NOT!!!
Do not write a template tag that runs logic or at worst, even run Python from a custom tag it defeats the purpose of a templating language dangerous difﬁcult to support

Django Templating @ PyCon 2012 by Christine Cheung Sad Tiems

Loading Templates

Django Templating @ PyCon 2012 by Christine Cheung Template Loading
Logic Use Cases TEMPLATE_LOADERS setting from django.conf import settings from django.template import TemplateDoesNotExist def load_template_source(template_name, template_dirs=None): for filepath in get_template_sources(template_name, template_dirs): try: # load in some templates yo except IOError: pass raise TemplateDoesNotExist(template_name)

Django Templating @ PyCon 2012 by Christine Cheung Replacing the
Templating Engine You can replace the built in templating engine Jinja2, Mako, Cheetah, etc But why? More familiar with another template language Performance Boost Different logic control and handling Risk “frankensteining” your project.

Django Templating @ PyCon 2012 by Christine Cheung Jinja2 and
Django and You Pros functions callable from templates loop controls multiple ﬁlter arguments slight performance increase

Django Templating @ PyCon 2012 by Christine Cheung Jinja2 and
Django and You Cons more dependencies and overhead extra time spent on development and support too much logic in templates minimal speed increase

Django Templating @ PyCon 2012 by Christine Cheung Speeding Up
Templates Cache Template Loader django-template-preprocessor compiles template files django-pancake flatten template files but also remember other bottlenecks...

Django Templating @ PyCon 2012 by Christine Cheung New in
Django 1.4 Custom Project and App templates startapp / startproject -- template combine with your favorite boilerplate Else if {% elif %}

Django Templating @ PyCon 2012 by Christine Cheung Questions ?
? ?

Django Templating - More Than Just Blocks

Django Templating - More Than Just Blocks

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