In Django's templates system, if I have a block that I want to make optional using an if statement, how do I do it?
I was trying this:
{% if val %}{% block title %}Archive {{ foo }}{% endblock %}{% endif %}
But that doesn't work. Is there a way to do that, so that for a given value (in this case Null) the block isn't issued and the base template uses the original values?
Edit:
Let me be a little more specific, so that it is easier to answer.
I have a page with 10 entries per page. The user can then go on to the next page and see the next ten items. For each further page they go, past the first, I would like to have the title tag say something like "Archive 1" or "Archive 10" but if they get back to the original page, it is no longer archive, and it should just go to the original site title already given in the base templates.
I ran into a similar issue with a project I'm working on. Here's how I resolved it using {{ block.super }} to pull the default value from the parent block:
My parent template contains:
{% block title %}Default Title{% endblock %}
My child template contains:
{% block title %}
{% if new_title %}{{ new_title }}{% else %}{{ block.super }}{% endif %}
{% endblock %}
*Note: You may want to wrap the code in {% spaceless %}{% endspaceless %} if you plan to use the result in an HTML title tag.
(It looks like Jordan Reiter posted the same solution in the comments of the original question a bit before my response.)
As far as I understand blocks are placeholders to be "overridden" in the child templates. They have to be defined at "compile time" and not at "run time".
As for your specific problem why not modify the title based on the page number (assuming you use pagination)? Something like this:
{% block title %}
{% ifequal page 1 %}Current{% else %}Archive {{ page }}{% endifequal %}
{% endblock %}
I would only have to add to the good answers above that depending on the Django version sometimes the {{ block.super }} puts the content from the master twice, this seems to happen in the most recent versions of Django.
I am using Django 1.8 and whenever i put the {{ block.super }} it started to behave in that way just as an addition to the Jamie answer i can say that in the base template you can put the content you wish
{% block title %} Default Title {% endblock %}
And then in the child if you want the footer to be inherited and displayed just do not do anything it will be. But if you do not want that block to be displayed then put the tag in the child with empty content just like this:
{% block title %}
{% endblock %}
Then it will be hidden once it is rendered also you can overwrite the content on it if you wish.
Related
Currently I have a block setup for my page titles in my base.html. It takes a unique value from each template page, and adds the website name to the end. For example: ABOUT US - My Site Name. The "ABOUT US" is passed by template and " - My Site Name" appears on every page regardless.
However, I want to use the same base.html on my index page, but only show "My Site Name." I was hoping to use an if statement by parsing the block each template passes to look for a unique value, signifying I am on the index page.
So far my code looks like this:
<title>
{% if {% block title %}{% endblock %} == "index_pg" %}
My Site Name
{% else %}
{% block title %}{% endblock %} - My Site Name
{% endif %}
</title>
obviously this doesn't work. Anyone ideas on how I can accomplish this? Thanks.
Typically I would use two blocks, one wrapped around the other, something like this:
# base.html template
<title>
{% block title %}
{% block inner_title %}{% endblock inner_title %} - The Stock Column
{% endblock title %}
</title>
So for most of your pages, you would extend base.html, and do this:
{% block inner_title %}Page XYZ{% endblock inner_title %}
And then on your index page, you would also extend base.html, but you would then do this:
{% block title %}TEST{% endblock title %}
The resulting output from the first one would be:
<title>Page XYZ - The Stock Column</title>
And the output of the second one, from your index page, would be:
<title>TEST</title>
A little question to jinja2 templating:
I want to create a reusable template to include and then overwrite blocks. Macros do not let me write junks of HTML easily as parameters do they? Say I want to reuse an include several times and am using BIG junks of HTML in blocks that I want to dynamically assign
how would I do it?
certainly not with macros I guess, or am I wrong?
{% render_foo('bar',2) %} is fine
{% render_foo('<table><tr><th>something</th><th>somethingelse</th></tr><tbody><tr>....etc') %} is not fine any more is it
"what do you really want to do?"
yes, what I told you, I have a way I create containers for my data. The container is ALWAYS the same. The content is completely different on each usage. Once a table. Once a bootstrap component. Once a form.
The surrounding elements are always the same
to reproduce the simple error this is what I did:
{% include 'full_section.html' %}
{% block fullsection %} <table><tr><th>something</th><th>somethingelse</th></tr><tbody><tr>....etc{% endblock %}
{% include 'full_section.html' %}
{% block fullsection %} <form>//some cool LONG big form </form>{% endblock %}
full_section.html contents just for completeness, it is a lot more complex in reality
<div class="my_cool_full_section">
{% block full_section %}{% endblock %}
</div>
TemplateAssertionError: block 'fullsection' defined twice
I found the answer well hidden in the jinja2 docs
http://jinja.pocoo.org/docs/2.9/templates/#block-assignments
so you use a macro and a block assignment e.g. like this:
{% set section_content %}
<table><tr><td>etc</td> <td>etc</td> <td>etc</td></tr></table>
<table><tr><td>etc</td> <td>etc</td> <td>etc</td></tr></table>
<table><tr><td>etc</td> <td>etc</td> <td>etc</td></tr></table>
{% endset %}
{{ render_full_size_section(section_content) }}
{% set section_content %}
aaaaaaaaaaa
{% endset %}
{{ render_full_size_section(section_content) }}
wonder what they were doing pre 2.8... dark dark middle age
then in the macro:
{% macro render_full_size_section(content) %}
<div class="mycoolsection">
{{ content | safe }}
</div>
{% endmacro %}
I am having trouble implementing django_breadcrumbs in a DRY fashion using block.super.
I have a template "editions" that the user can reach in one of two ways: either from home, in which case the user sees all the editions, or from the template "surveys", in which case the user sees only the editions for that survey.
The breadcrumbs for the editions template look like this and they work fine:
{% extends 'base.html' %}
{% load django_bootstrap_breadcrumbs %}
{% block breadcrumbs %}
{{ block.super }}
{% if slug %}
{% breadcrumb "Surveys" "surveys:index" %}
{% breadcrumb "Editions" "editions:index" slug=slug %}
{% else %}
{% breadcrumb "Editions" "editions:index" %}
{% endif %}
{% endblock %}
Disappoinment ensues for pages that hang off the editions template. I had hoped that by extending that page and using block.super, I would inherit the proper breadcrumbs depending on where the edition came from. But I only ever get the Editions breadcrumb even when I hoped for the Surveys / Editions breadcrumbs.
Here is the template "create" which hangs off "edition":
{% extends 'editions/index.html' %}
{% load bootstrap3 %}
{% load django_bootstrap_breadcrumbs %}
{% block breadcrumbs %}
{{ block.super }}
{% breadcrumb "Create" "editions:create" %}
{% endblock %}
I could always put another if: else: in that template, but I would rather just inherit the if: else: from the previous template. What is it I don't understand? Do I need to pass the slug back up to the super:block or something? How would I do that without repeating the same if: else: in the child template? Indeed, how would I do that at even with a new if: else:?
thanks
John
My best guess is that you render the second template without passing the slug variable. Your inheritance is correct, but as the parent (or super) template uses the slug variable, what it renders depends on the variable's contents. Therefore, if no variable called slug is passed, you will always get the else-part of your if statement.
So, the solution seems quite simple: add the slug variable to the context parameter when triggering the template render.
Apologies, this is pretty basic. I have abstracted my static html navigation bar to a block so that it can be dynamically rendered from a model. I have created a new block marker in base.html with the following syntax
{% block navigation %}{% endblock %}
How can I ensure this is rendered on every page? Do I need to create some sort of middle layer for this? Everything I have done so far has simply used the primary block.
EDIT Sunday, 14 August 2011 11:25 AM
I didn't explain this very well. The content of navigation block is
{% extends 'base.html' %}
{% block navigation %}
<nav>
<ul>
{% for item in items %}
<li>{{ item.name }}</li>
{% endfor %}
</ul>
</nav>
{% endblock %}
I want to render this on every page without having to go through child templates of base.html individually and add it to them, if that is possible.
You have got static navigation bar, so you can just write code in your base.html page and then use it with {% extends 'base.html' %} tag on every new page. Your markup will be in every page. Also, if you use only extends tag in your child page and then render it - you will see base.html without any edition.
If you have got code, which need to appear on few pages, but not on everyone - create 'includes' directory, save code there and extend your base template with {% include %} tag. It won't avoid repating, but make your code shorter.
And last thing you'll need in future, maybe with dynamic code - caching. With {% cache %} tag you can cache block for some time.
Your block is not doing anything here, but if you want something to appear in all the templates, you have to define it in a base template (base.html) and make the others extend from it:
base.html
Yor menu and the stuff you want to appear everywhere
{% block content %}{% endblock %}
Another template
{% extends "base.html" %}
{% block content %}
The actual content of the page
{% endblock %}
{% block FOO %}{% endblock %} reserves a space to be overwritten in sub templates.
{% include "foo.html" %} pulls content from another file into the current file.
To get {% block navigation %}{% endblock %} to display on every page, you need to add content
{% block navigation %}SHOW ME{% endblock %}
Am working with django Publisher example, I want to list all the publishers in the db via my list_publisher.html template, my template looks like;
{% extends "admin/base_site.html" %}
{% block title %}List of books by publisher{% endblock %}
{% block content %}
<div id="content-main">
<h1>List of publisher:</h1>
{%regroup publisher by name as pub_list %}
{% for pub in pub_list %}
<li>{{ pub.name }}</li>
{% endfor %}
</div>
{% endblock %}
but when I run "http://127.0.0.1:8000/list_publisher/" the template just prints the page title with no error! What am I doing wrong?
A few suggestions:
check that your base_site.html does define a {% block content %}{% endblock %} section to be refine by your my list_publisher.html
check the cardinality of your list: {%regroup publisher by name as pub_list %}{{ pub_list|length }}. That should at least display the length of your list. If is is '0'... you know why it does not display anything
check that your list is indeed sorted by name before using regroup, or use a {% regroup publisher|dictsort:"name" by name as pub_list %} to be sure
If the length is '0', you have to make sure publisher is defined (has been initialized from the database), and sorted appropriately.
In other word, do you see anywhere (in your template or in the defined templates):
publisher = Publisher.objects.all().order_by("name")
?
(again, the order by name is important, to ensure your regroup tag works properly)
Good answer by VonC.
A quick and dirty way to look at pub_list is to stick [{{pub_list}}] in your template. I put it in square brackets in case it's empty. BTW, you may get something that looks like [,,,,,]. This is because object references are wrapped in <> and your browser is going WTF? Just do a View Source and you'll see the full result.