In short, how to use JavaScript in the component that will be then included in the main page?
A standard approach in Django templates is to create a base.html template and then extend it. That base template usually has blocks like content, extra_js, and extra_css. The extended template looks like
{% extend 'base.html' %}
{% block content %}
<div>
some content
</div>
{% endblock %}
{% block extra_js %}
# some js code here
{% endblock %}
I need to create a component that will be included on several pages and I need to use JavaScript inside that component. I know that it will be included only on pages that extend base.html, the page that includes it will look like
{% extend 'base.html' %}
{% block content %}
<div>
{% include 'component.html' %}
</div>
{% endblock %}
{% block extra_js %}
# some js code here
{% endblock %}
However, component.html knows nothing about extra_js block because it doesn't extend base.html, I cannot use that block in component.html, and if I just put some JavaScript code in it then after the template is rendered any JavaScript in component.html will end up being in the middle of the body of the document, will be executed before libraries like jQuery are imported and will not work. What is the right way to work around it?
Related
I noticed that I started using include template a lot. One of my template files has 20+ include tags.
Some of them are for modal dialogs that in turn have include for different form field sets. I am also using basically the same buttons with different data attributes so these are also done with include tags. Some my "fragments" that I use with include have around only five lines of HTML code.
I worry if this is too much and can negatively affect performance (since Django loads another files, etc..)
For example whis is markup of one of my HTML fragments I am using with include:
<div class="form-group">
<input type="url" class="form-control" id="video-link-input" name="video_link"
placeholder="YouTube link">
</div>
<input type="hidden" id="video_id" name="video_id" value="">
<img class="img-fluid img-thumbnail" id="video-img-preview">
Hope the question is not too broad. I would just like to avoid possible bad practice.
Overly fragmented templates will impact your performance, but not because Django loads files.
With the default settings, Django caches template files when DEBUG=False:
django.template.loaders.cached.Loader
...
This loader is automatically enabled if OPTIONS['loaders'] isn’t
specified and OPTIONS['debug'] is False (the latter option defaults to
the value of DEBUG).
IMHO, having lots of includes is not a bad practice in itself. The alternative would be repeating the code, which violates the DRY principle.
If you find yourself including the same template multiple times within one template, you might want to consider a custom inclusion tag.
If you are really worried about performance, look into caching and specifically template fragment caching.
According to Django documentation:
using {% block %} is faster than using {% include %}
heavily-fragmented templates, assembled from many small pieces, can
affect performance
You can use extends and block
Few examples:
In base.html I use these blocks
...
{% block navbar %}
{% endblock %}
{% block sidebar %}
{% endblock %}
{% block searchbar %}
{% endblock %}
{% block content %}
{% endblock %}
{% block footer %}
{% endblock %}
...
Now I extend base.html into login.html. Say my login.html just need navbar, content, and footer
{% extends 'base.html' %}
<h1>Login </h1>
{% block navbar %}
This is my navbar
{% endblock %}
{% block content %}
Here is my login form
{% endblock %}
{% block footer %}
This is footer
{% endblock %}
Now I extend base.html into home.html. Say my home.html need navbar, sidebar, searchbar, content, and footer
{% extends 'base.html' %}
<h1>Home page </h1>
{% block navbar %}
This is my navbar
{% endblock %}
{% block sidebar %}
This is sidebar
{% endblock %}
{% block searchbar %}
{% endblock %}
{% block content %}
This is homepage contents. This will not render which you use in login.html **content** block
{% endblock %}
{% block footer %}
{% endblock %}
Sometimes I get an empty string returned for my include tags which is impossible, because I have some static elements in it.
This is happening sometimes in my productive environment. How can I debug such an issue?
For example my footer or header disappears in some cases (Which I include within my "base.html") which I can't reproduce.
Thx
Example:
base.html
<html>
...
{% include "subdir/_header.html" %}
...
{% block content %}
<h1>Default Content</h1>
{% endblock %}
...
{% include "subdir/_footer.html" %}
</html>
home.html
{% extends "base.html" %}
{% block content %}
<h1>Home related Content</h1>
{% endblock %}
So if I load home.html my footer sometimes disappears. No idea why, no errors.
FOUND THE PROBLEM
A missing static file caused that kind of problem. Unfortunately I did not get an error.
I don't know the exact reason of this issue, but can you try with {% extends 'base.html' %}.
The difference between include and extends right here:
{% include %} vs {% extends %} in django templates
Your base html should be Extended and not Included... include is for small blocks of codes, like components... blog post, news, contact and that stuffs
base html
{% load static %}
<!DOCTYPE html>
<html lang="en-US">
{% include 'path/head.html' %}
{% block content %}{% endblock %}
{% include 'path/footer.html' %}
</html>
other pages
{% extends 'base.html' %}
{% load static %}
{% block content %}
<!-- Content from each page -->
{% endblock %}
Obs.: Include inside of includes dont work propely, you can get the data from first page in includes inside includes... for that i usualy use templatetags or context_processors, depending of your need.
Use django-debug-toolbar to debug your entire application in dev environment, you can see the entire request and the includes that you want
https://django-debug-toolbar.readthedocs.io/en/stable/
I have a piece of html that I want present in all pages, except one. If not for this page, I would have put it in the base.html and extended.
Is there a way other than putting the code individually in all the required pages?
From template-inheritance docs,
The template engine will notice the {% block %} tags in base.html and replace those blocks with the contents of the child template.
BUT
If the child template didn’t define the block, the value from the
parent template is used instead. Content within a {% block %} tag in a
parent template is always used as a fallback.
So in that case you can use {% block %} tag in the base.html.
{% block content %}
<!-- Your content here-->
{% endblock %}
You don't have to define that block in every template as the parent {% block %} is used as an fallback.
{% extends 'base.html' %}
So in your exceptional case just define that {% block %} tag with no data or something else.
{% extends 'base.html' %}
{% block content %}
<!-- Nothing goes here -->
{% endblock content %}
You can put it into a block that gets overridden with nothing in order to have it ignored. For example:
base.html
{% block content %}
<div>
This should show on all pages except for this one
</div>
{% endblock content %}
included-page.html (The div will be included on this page)
{% extends 'base.html' %}
ignored-page.html (The div will be ignored on this page)
{% extends 'base.html' %}
{% block content %}
{% endblock content %}
I have a base template (base.html) like this:
<doctype html> etc etc
{% block content %}{% endblock %}
It is used by many other templates in my site, but I have a third party app that comes with its own templates which inherit from tp.html which in turn inherits from base.html. These templates are mostly fine but I need their content blocks to be wrapped in a div. I could change the third party templates to use a sub_content block and modify tp.html like so:
{% extends "base.html" %}
{% block content %}
<div class="third-party-app">
{% block sub_content %}{% endblock %}
</div>
{% endbock %}
but I don't want to have to modify all the templates in the third party app.
What I want is something similar to {$smarty.block.child} found in Smarty templates, or a way to achive the same. Any ideas?
You can use block.super like so:
3rd party template:
{% block content %}
<h1>3rd Party Content</h1>
{% endblock %}
your template:
{% block content %}
<div class="wrapper">{{ block.super }}</div>
{% endblock content %}
In base.html, add pre_content and post_content blocks either side of {% block content %}, then in tp.html add your and tags to these blocks. Slightly inelegant, but it'll work and you won't have to modify all your templates.
I'm trying to create stand-alone front-end module (HTML, CSS & JS) to integrate into a Django app.
The best example for what I mean is a "map" module, which I'd like to include in various, unrelated pages, possibly in different locations in each page.
I have a template that provides the HTML code that I need for the map, and I'd like the CSS and JS code to also be included through this template, to ease handling of front end dependencies.
Up until now, this can be achieved using the {% include %} tag.
But including stylesheets and scripts in the middle of the HTML page is an extremely bad practice when it comes to front-end performance. (CSS should be included in the <head>, JS should be included at the end of <body>)
My problem could have been solved if {% include %} tags would have been rendered as part of the template that included them and could have overridden {% block %} tags. That is not the case in Django. {% include %} tags are first rendered to HTML and only then included, so they cannot override {% block %} tags.
Looking around past questions around this subject suggest that the common wisdom is to use template inheritance (i.e. {% extends %}) instead of {% include %}, but since I'd like my modules to be independent, I don't see how I can use inheritance in my case.
What can I do to maintain my front-end dependencies inside the templates while maintaining front-end performance best practices?
Thanks!
To create your map template tag in the first place, use inclusion tags.
Concerning the problem with the static files, I'd create a related template tag that dumps the static file references into your current template. Then include that template tag in a block.
If your base template is in base.html and the page template is at page.html:
base.html
<html>
<head>
{% block css %}
<link rel="stylesheet...
{% endblock %}
</head>
<body>
{% block content %}{% endblock %}
{% block scripts %}{% endblock %}
</body>
</html>
page.html
{% extends 'base.html' %}
{% block css %}
{{ block.super }}
{% map_css %}
{% endblock %}
{% block scripts %}
{{ block.super }}
{% map_scripts %}
{% endblock %}
{% block content %}
content...
{% map_html %}
content...
{% endblock %}