Super URLs for Django
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Spurl is a Django template library for manipulating URLs. It's built on top of Zachary Voase's excellent urlobject.
Authored by Jamie Matthews, and some great contributors.
Installation
Either checkout spurl
from GitHub, or install using pip:
pip install django-spurl
Add spurl
to your INSTALLED_APPS
:
INSTALLED_APPS = (
...
'spurl',
)
Finally, whenever you want to use Spurl in a template, you need to load its template library:
{% load spurl %}
Usage
Spurl is not a replacement for Django's built-in {% url %}
template tag. It is a general-purpose toolkit for manipulating URL
components in templates. You can use it alongside {% url %}
if you
like (see below).
Spurl provides a single template tag, called (surprisingly enough),
spurl
. You call it with a set of key=value
keyword arguments,
which are described fully below.
To show some of the features of Spurl, we'll go over a couple of simple example use cases.
Adding query parameters to URLs
Say you have a list of external URLs in your database. When you create
links to these URLs in a template, you need to add a
referrer=mysite.com
query parameter to each. The simple way to do
this might be:
{% for url, title in list_of_links %}
<a href="{{ url }}?referrer=mysite.com">{{ title }}</a>
{% endfor %}
The problem here is that you don't know in advance if the URLs stored in
your database already have query parameters. If they do, you'll
generate malformed links like
http://www.example.com?foo=bar?referrer=mysite.com
.
Spurl can fix this. Because it knows about the components of a URL, it can add parameters onto an existing query, if there is one.
{% for url, title in list_of_links %}
<a href="{% spurl base=url add_query="referrer=mysite.com" %}">{{ title }}</a>
{% endfor %}
Note that when you pass a literal string to Spurl, you have to wrap it in double quotes. If you don't, Spurl will assume it's a variable name and try to look it up in the template's context.
SSL-sensitive external URLs.
Suppose your site needs to display a gallery of images, the URLs of
which have come from some third-party web API. Additionally, imagine
your site needs to run both in secure and non-secure mode - the same
content is available at both https
or http
URLs (depending on
whether a visitor is logged in, say). Some browsers will complain loudly
(displaying "Mixed content warnings" to the user) if the page being
displayed is https
but some of the assets are http
. Spurl can
fix this.
{% for image_url in list_of_image_urls %}
<img src="{% spurl base=image_url secure=request.is_secure %}" />
{% endfor %}
This will take the image URL you supply and replace the scheme component
(the http
or https
bit) with the correct version, depending on
the return value of request.is_secure()
. Note that the above assumes
you're using a RequestContext
so that request
is available in
your template.
{% url %}
Using alongside Notice that Spurl's functionality doesn't overlap with Django's built-in
{% url %}
tag. Spurl doesn't know about your urlconf, and doesn't do
any URL reversing. In fact, Spurl is mostly useful for manipulating
external URLs, rather than URLs on your own site. However, you can
easily use Spurl with {% url %}
if you need to. You just have to use
the as
keyword to put your reversed URL in a template variable, and
then pass this to Spurl. As it's a relative path (rather than a full
URL) you should pass it using the path
argument. For example, say
you want to append some query parameters to a URL on your site:
{% url your_url_name as my_url %}
<a href="{% spurl path=my_url query="foo=bar&bar=baz" %}">Click here!</a>
There is another way to use Spurl with {% url %}
, see Embedding
template tags below.
Available arguments
Below is a full list of arguments that Spurl understands.
base
If you pass a base
argument to Spurl, it will parse its contents and
use this as the base URL upon which all other arguments will operate. If
you don't pass a base
argument, Spurl will generate a URL from
scratch based on the components that you pass in separately.
scheme
Set the scheme component of the URL. Example:
{% spurl base="http://example.com" scheme="ftp" %}
This will return ftp://example.com
See also: scheme_from
, below.
host
Set the host component of the URL. Example:
{% spurl base="http://example.com/some/path/" host="google.com" %}
This will return http://google.com/some/path/
See also: host_from
, below.
auth
Handle HTTP Basic authentication, username and password can be passed in URL. Example:
{% spurl base="https://example.com" auth="user:pass" %}
This will return https://user:[email protected]
path
Set the path component of the URL. Example:
{% spurl base="http://example.com/some/path/" path="/different/" %}
This will return http://example.com/different/
See also: path_from
, below.
add_path
Append a path component to the existing path. You can add multiple
add_path
calls, and the results of each will be combined. Example:
{% spurl base=STATIC_URL add_path="javascript" add_path="lib" add_path="jquery.js" %}
This will return http://cdn.example.com/javascript/lib/jquery.js
(assuming STATIC_URL
is set to http://cdn.example.com
)
See also: add_path_from
, below.
fragment
Set the fragment component of the URL. Example:
{% spurl base="http://example.com" fragment="myfragment" %}
This will return http://example.com/#myfragment
See also: fragment_from
, below.
port
Set the port component of the URL. Example:
{% spurl base="http://example.com/some/path/" port="8080" %}
This will return http://example.com:8080/some/path/
See also: port_from
, below.
query
Set the query component of the URL. Example:
{% spurl base="http://example.com/" query="foo=bar&bar=baz" %}
This will return http://example.com/?foo=bar&bar=baz
The query
argument can also be passed a dictionary from your
template's context.
# views.py
def my_view(request):
my_query_params = {'foo': 'bar', 'bar': 'baz'}
return render(request, 'path/to/template.html', {'my_query_params': my_query_params})
<!-- template.html -->
{% spurl base="http://example.com/" query=my_query_params %}
This will return http://example.com/?foo=bar&bar=baz
Finally, you can pass individual template variables to the query. To do this, Spurl uses Django's template system. For example:
{% spurl base="http://example.com/" query="foo={{ variable_name }}" %}
See also: query_from
, below.
add_query
Append a set of parameters to an existing query. If your base URL might already have a query component, this will merge the existing parameters with your new ones. Example:
{% spurl base="http://example.com/?foo=bar" add_query="bar=baz" %}
This will return http://example.com?foo=bar&bar=baz
You can add multiple add_query
calls, and the results of each will
be combined:
{% spurl base="http://example.com/" add_query="foo=bar" add_query="bar=baz" %}
This will return http://example.com?foo=bar&bar=baz
Like the query
argument above, the values passed to add_query
can also be dictionaries, and they can contain Django template
variables.
See also: add_query_from
, below.
set_query
Appends a set of parameters to an existing query, overwriting existing
parameters with the same name. Otherwise uses the exact same syntax as
add_query
.
See also: set_query_from
, below.
toggle_query
Toggle the value of one or more query parameters between two possible values. Useful when reordering list views. Example:
{% spurl base=request.get_full_path toggle_query="sort=ascending,descending" %}
If the value of request.get_full_path()
doesn't have a sort
parameter, one will be added with a value of ascending
(the first
item in the list is the default). If it already has a sort
parameter, and it is currently set to ascending
, it will be set to
descending
. If it's already set to descending
, it will be set to
ascending
.
You can also specify the options as a dictionary, mapping the parameter name to a two-tuple containing the values to toggle. Example:
# views.py
SORT_PARAM = 'sort'
ASCENDING = 'ascending'
DESCENDING = 'descending'
def my_view(request):
if request.GET.get(SORT_PARAM, ASCENDING) == DESCENDING:
object_list = MyModel.objects.order_by('-somefield')
else:
object_list = MyModel.objects.order_by('somefield')
return render(request, 'path/to/template.html', {
'object_list': object_list,
'sort_params': {SORT_PARAM: (ASCENDING, DESCENDING)},
})
<!-- template.html -->
<a href="{% spurl base=request.get_full_path toggle_query=sort_params %}">Reverse order</a>
remove_query_param
Remove a query parameter from an existing query:
{% spurl base="http://example.com/?foo=bar&bar=baz" remove_query_param="foo" %}
This will return http://example.com?bar=baz
Again, you can add multiple remove_query_param
calls, and the
results will be combined:
{% spurl base="http://example.com/?foo=bar&bar=baz" remove_query_param="foo" remove_query_param="bar" %}
This will return http://example.com/
You can also remove parameters with specific values:
{% spurl base="http://example.com/?foo=bar&bar=baz&foo=baz" remove_query_param="foo" remove_query_param="foo=baz" %}
This will return http://example.com/?bar=baz
Finally, you can pass individual template variables to the
remove_query_param
calls. To do this, Spurl uses Django's template
system. For example:
{% spurl base="http://example.com/?foo=bar&bar=baz" remove_query_param="{{ variable_name }}" %}
secure
Control whether the generated URL starts with http
or https
. The
value of this argument can be a boolean (True
or False
), if
you're using a context variable. If you're using a literal argument
here, it must be a quoted string. The strings "True"
or "on"
(case-insensitive) will be converted to True
, any other string will
be converted to False
. Example:
{% spurl base="http://example.com/" secure="True" %}
This will return https://example.com/
autoescape
By default, Spurl will escape its output in the same way as Django's
template system. For example, an &
character in a URL will be
rendered as &
. You can override this behaviour by passing an
autoescape
argument, which must be either a boolean (if passed from
a template variable) or a string. The strings "True"
or "on"
(case-insensitive) will be converted to True
, any other string will
be converted to False
.
_from
parameters
Added bonus: As well as those listed above, Spurl provides a family of parameters for
combining URLs. Given a base URL to start with, you can copy a
component from another URL. These arguments expect to be passed a full
URL (or anything that can be understood by URLObject.parse
). This
URL will be parsed, and then the component in question will be extracted
and combined with the base URL.
Below is a full list of the available _from
methods. They have
identical semantics to their counterparts above (except they expect a
full URL, not just a URL component).
query_from
add_query_from
set_query_from
scheme_from
host_from
path_from
add_path_from
fragment_from
port_from
Example:
{% spurl base="http://example.com/foo/bar/?foo=bar path_from="http://another.com/something/?bar=foo" %}
This will return http://example.com/something/?foo=bar
Building a URL without displaying it
Like Django's {% url %}
tag, Spurl allows you to insert the
generated URL into the template's context for later use. Example:
{% spurl base="http://example.com" secure="True" as secure_url %}
<p>The secure version of the url is {{ secure_url }}</p>
Embedding template tags
As mentioned above, Spurl uses Django's template system to individually parse any arguments which can be passed strings. This allows the use of syntax such as:
{% spurl base="http://example.com" add_query="foo={{ bar }}" %}
This works fine for variable and filters, but what if we want to use
other template tags inside our Spurl tag? We can't nest {%
and
%}
tokens inside each other, because Django's template parser would
get very confused. Instead, we have to escape the inner set of tag
markers with backslashes:
{% spurl base="http://example.com" add_query="next={\% url home %\}" %}
Note that any tags or filters loaded in your template are automatically available in the nested templates used to render each variable. This means we can do:
{% load url from future %}
{% spurl base="{\% url 'home' %\}" %}
Be careful with your quotation marks! If you use double-quotes to surround the nested template, you have to use single quotes inside it.
Warning! This functionality only exists to serve the most complex of use cases, and is extremely magical (and probably a bad idea). You may prefer to use:
{% url "home" as my_url %}
{% spurl base=my_url %}
Development
To contribute, fork the repository, make your changes, add some tests, commit, push, and open a pull request.
How to run the tests
Spurl is tested with nose. Clone the
repository, then run pip install -r requirements.txt
to install nose
and Django into your virtualenv. Then, simply type nosetests
to find
and run all the tests.
(Un)license
This is free and unencumbered software released into the public domain.
Anyone is free to copy, modify, publish, use, compile, sell, or distribute this software, either in source code form or as a compiled binary, for any purpose, commercial or non-commercial, and by any means.
In jurisdictions that recognize copyright laws, the author or authors of this software dedicate any and all copyright interest in the software to the public domain. We make this dedication for the benefit of the public at large and to the detriment of our heirs and successors. We intend this dedication to be an overt act of relinquishment in perpetuity of all present and future rights to this software under copyright law.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
For more information, please refer to http://unlicense.org/
Artwork credit
Superman ASCII art comes from http://ascii.co.uk/art/superman