In the Django tutorial (part 3), they have the following syntax for a template:
{% if latest_poll_list %}
<ul>
{% for poll in latest_poll_list %}
<li>{{ poll.question }}</li>
{% endfor %}
</ul>
{% else %}
<p>No polls are available.</p>
{% endif %}
Can someone explain exactly hwo the {% something %} syntax is supposed to work? Thank you for your help!
They are template-tags. In the relevant part of the actual Python-code the tutorial does this:
from django.http import HttpResponse
from django.template import RequestContext, loader
from polls.models import Question
def index(request):
latest_question_list = Question.objects.order_by('-pub_date')[:5]
template = loader.get_template('polls/index.html')
context = RequestContext(request, {
'latest_question_list': latest_question_list,
})
return HttpResponse(template.render(context))
This is the view. In this view they populate latest_question_list with the five newest questions from the database. Then the view is told to render the output with these values.
The view then loads the template (the code you posted) and replaces the tags/placeholders with actual data from the corresponding object.
The template-tags should be pretty self-explainable. The first line checks if there are any questions provided. If it is, loop them and {{ poll.id }} etc will then be replaced by the actual data from the query.
This is more or less the "core" of this type of design. The idea is to separate the logic and the markup as much as possible. You should have all your code in the views and just the plain markup and template-tags in the template-files. It provides a much cleaner environment and makes it much easier to maintain.
Related
I'm doing some pagination in Django. I want to show the pages' number which are ahead of the current page. I am using the following code:
{% for page in blogs_page.paginator.page_range|slice:"0:{{ blogs_page.number }}" %}
But this seems useless; the result does the same as the following:
{% for page in blogs_page.paginator.page_range %}
The slice does not work here. How do I fix this?
Never use {{ }} inside of {% %}, don't do this {% {{ }} %}.
{% for page in blogs_page.paginator.page_range|slice:"0:blogs_page.number" %}
I think it won't work. If I were you I would create a custom tag and executed all the logic there. So, it will look like this:
Template:
{% custom_tag blogs_page as result %}
{% for page in result %}
templatetags/tags.py:
from django import template
register = template.Library()
#register.simple_tag
def custom_tag(bl_page):
return bl.page.paginator.page_range[0:bl_page.number]
Details: custom tags
I am trying to simplify my code by creating a custom template tag for a 'for loop' that use frequently on my Django web application. I thought it would be a simple straight process, but something isn't working right... I can use some assistance in catching my error.
Here is my code.
views.py
class ArticleView(DetailView):
model = Articles
def get_context_data(self, **kwargs):
context = super(ArticleView, self).get_context_data(**kwargs)
context['s_terms'] = scientific_terms.objects.all()
return context
template tag
#register.filter(name='term')
def term(value):
{% for term in s_terms %}
{{ term.short_description }}
{% endfor %}
template.html
{% Neurons|term %}
Thank you for your assistance, in advance.
You are mixing Python code with the Django Template Language. The template tags are plain Python code, as they are defined inside a Python module. A working example would be:
#register.filter(name='term')
def term(terms):
output = ''
for term in terms:
output = '{0} {1}'.format(output, term.short_description)
return output
Then you could use it like this:
{{ s_terms|term }}
Maybe what you want is simply to create a reusable Django template.
For example, create a new template named terms.html:
templates/terms.html
{% for term in terms %}
<p>{{ term.short_description }}</p>
{% endfor %}
Then, in another template, you could include this partial template:
templates/index.html (name is just an example)
{% extends 'base.html' %}
{% block content %}
<h1>My application</h1>
{% include 'terms.html' with terms=s_terms %}
{% endblock %}
I want to loop data taken from database in rendered template. Using cms plugin.
I dont have problem looping data in html template. But if i use CMSPlugin to insert new app in placeholder, nothing shows.
If i run url localhost:port/test.html.I got input what i want. But rendered template doesnt loop data.
{% for post in posts %}
{{ post.firstoption }}
{% endfor %}
if I use code below, nothing shows in my rendered template. Values are passed in rendered template. Because, if i try {{instance.firstoption}} i get value shown in template. Problem is i cant loop data with tag instance.
{% for post in instance.posts %}
{{ post.firstoption }}
{% endfor %}
I also tried {% for post in instance.posts_set.all %}
and {% for post in instance.posts.all %}
cms_plugins.py
class pricing(CMSPluginBase):
model = mymodel
name = _("myplugin")
render_template = "template.html"
cache = False
def render(self, context, instance, placeholder):
context.update({'instance': instance})
return context
models.py
class mymodel(CMSPlugin):
firstoption = models.CharField(max_length=200)
def __str__(self):
return self.firstoption
It is probably because you need to call all on your posts
{% for post in instance.posts.all %}
{{ post.firstoption }}
{% endfor }
I'm trying to build a website that has products and categories.
When you are on the page of a product, you can click a button to see a list of all the categories it falls under.
You can click another button, that appears on all pages, to see a list of all the categories overall.
In the html page see_all_categories, I wrote a simple block like this:
{% extends 'base.html' %}
{% load staticfiles %}
{% block content%}
{{Category.all}}
{% endblock content %}
I expect to see a messy printout of all the categories but I don't. It doesn't return an error, but it produces nothing, other than the base.html.
What am I doing wrong?
You want to display a list of the categories. I assume your Category model owns an attribute named "title" which is the representation of your Category.
If you're using Django template engine or Jinja2, you can make a for loop inside your template like this :
{% for cat in Category.objects.all %}
{{ cat.title }}
{% endfor %}
As a troubleshooting, I'd suggest you didn't pass your Category model to your template, that is not done automatically. You have to add your model to the context before rendering the template.
As mentionned in the comments, here is doc for template rendering with Django templates.
Django Template Guide
To add your model to the context you can follow this guide.
I don't intend to help you further because I lack of information and that may vary a LOT according to your settings. (Class Based views ? Function based views ? What kind of template are you using... And so on)
I figured out the solution after many long annoying hours of trying everything. I feel dumb but I want to spare the next guy the massive pain in the two-pack.
This is what I did:
In the Views.py, I changed the view function for this page FROM this:
def view_all_categories(request):
context = {'Category' : Category}
return render(request, 'store/see_all_categories.html', context)
TO this
def view_all_categories(request):
all_cats = Category.objects.all().order_by('id')
context = {'all_categories' : all_cats}
return render(request, 'store/see_all_categories.html', context)
and in the page see_all_categories.html itself, I changed it (from the question) TO this:
{% extends 'base.html' %}
{% load staticfiles %}
{% block content%}
{% for cat in all_categories %}
<p>{{ cat.name }}</p>
{% endfor %}
{% endblock content %}
And now it works!!
I am using Django's Template Fragment Caching so in a template.html file
{% extends 'base.html' %}
{% load cache %}
{% block content %}
{% cache 500 "myCacheKey" %}
My html here...
{% endcache %}
{% endblock %}
This is working fine - I can see it's getting cached and hit but the view is doing something expensive to provide data to this view and thats getting called every time.
In views.py
def index(request)
data = api.getSomeExpensiveData()
return render_to_response('template.html', {'data':data} )
So how do I tell if the cache is avail before the call to api.getSomeExpensiveData()?
I can't use cache.get('myCacheKey') as the cache isn't found - does it use some naming scheme and if so can I either use something like
cache.get(cache.getTemplateFragmentKey("myCacheKey"))
or
cache.getTemplateFragment("myCacheKey")
If you do not use that data in your view, something as simple as this might work:
def index(request)
get_data = api.getSomeExpensiveData
return render_to_response('template.html', {'get_data':get_data} )
In template
{% block content %}
{% cache 500 "myCacheKey" %}
{{ get_data.something }}
Or maybe
{% for something in get_data %}
{% endfor %}
{% endcache %}
{% endblock %}
Django template automatically calls all callable objects.
EDIT:
If you need to use get_data more than once in your template you'll need some wrapper. Something similar to this:
def index(request)
class get_data(object):
data = False
def __call__(self):
if not self.data:
self.data = api.getSomeExpensiveData()
return self.data
return render_to_response('template.html', {'get_data':get_data()} )
I found this SO - How do I access template cache?
And adapted it to
from django.utils.hashcompat import md5_constructor
from django.utils.http import urlquote
from django.core.cache import cache
def hasFragmentCache(key, variables = []):
hash = md5_constructor(u':'.join([urlquote(var) for var in variables]))
return cache.has_key(cache_key)
Edit - I've accepted skirmantas answer as whilst this does exactly as asked its the better approach as then the template and view are more loosly coupled. Using this method you need to know the name of each cache fragment and whats used where. A designer moves things around and it would fall over.