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Django URL tools

Overview

Django URL tools are context processors, and template tags that help you deal with URL manipulations in templates. The heavy lifting is done by the url_tools.helper.UrlHelper class which wraps around urllib, urlparse, and Django's QueryDict to provide facilities for parsing and manipulating URLs.

Installation

Simply install the django-url-tools package using easy_install or pip:

pip install django-url-tools

Configuring your Django project

To use the context processor, add the following to the middlewares stack:

TEMPLATE_CONTEXT_PROCESSORS = (
    ...
    'url_tools.context_processors.current_url',
)

If you want to use the template tags, add url_tools to installed apps:

INSTALLED_APPS = (
    ...
    'url_tools',
)

UrlHelper class

UrlHelper class implements all methods for manipulating URLs that are used in other parts of this app. You can also use this class directly by importing it from the helper module:

from url_tools.helper import UrlHelper

UrlHelper constructor accepts only one argument, which is the full path of the URL you want to manipulate. Although we can technically make UrlHelper deal with full absolute URLs, we have opted to implement only methods for dealing with paths instead. Therefore, if you pass UrlHelper an full URL with scheme, host, port, and user credentials, it would still only use the path, query parameters, and the fragment identifiers.

You can also pass an instance of UrlHelper class to the constructor if you need to do so.

The class has following properties:

  • path: URL's path without query string and fragment identifier
  • fragment: URL's fragment identifier (without the pound character #)
  • query_dict: QueryDict instance containing the URL's query parameters
  • query: similar to query_dict but also does more when assigning
  • query_string: URL's query string
  • hash: MD5 hexdigest of the full path including query parameters

UrlHelper.path

This is a simple string property containing the URl's path. For example, in an URL '/foo/bar?baz=1#boo', the property contains '/foo/bar'.

UrlHelper.fragment

Contains the fragment identifier. In the URL '/foo/bar?baz=1#boo', this property contains 'foo'.

UrlHelper.query_dict

Contains the query parameters parsed from the URL in form of django.http.request.QueryDict instance. You can read more about the QueryDict API in Django documentation on QueryDict.

UrlHelper.query

This is a property returns the UrlHelper.query_dict when read, but overrides it when assigend a normal dictionary or a string. For example:

u = UrlHelper('/foo/bar')
u.query = 'foo=1&bar=2'
# or
u.query = dict(foo=1, bar=2)

Both above assignment work.

UrlHelper.query_string

This property returns a query string when read, and behaves the same way as the query property when assigning a string. However, you cannot assign dictionaries to this property.

u = UrlHelper('/foo/bar')
u.query_string = 'foo=1&bar=2'       # this works
u.query_string = dict(foo=1, bar=2)  # but this doesn't

UrlHelper.hash

Returns the MD5 hexdigest of the full path including query parameters. This can be useful for use with caching and other situations where we need to differentiate same paths with different query parameters.

u = UrlHelper('/foo/bar')
u.query = dict(foo=1) # URL is now '/foo/bar?foo=1'
u.hash  # returns '06f0a42bdd474f053fb1343165a31d42'

UrlHelper.get_query_string(**kwargs)

This method returns the query string using QueryDict's urlencode() method. Any keyword parameters you pass to this method are forwarded to the urlencode() method. Currently, the only keyword argument is safe which instructs the method to not escape specified characters.

UrlHelper.get_query_data()

Returns the UrlHelper.query_dict property. This methods exist mostly to help customize the behavior of UrlHelper.query in subclasses, since the getter calls this method instead of returning the query_dict property directly.

UrlHelper.update_query_data(**kwargs)

This method takes any number of keyword arguments and updates the UrlHelper.query_dict instance. Since, unlike Python dictionary, each QueryDict key can have multple values, you can pass multiple values as Python iterables such as lists or tuples. For example:

u = UrlHelper('/foo')
u.update_query_data(bar=[1, 2, 3])
u.query_string  # returns 'bar=1&bar=2&bar=3'

UrlHelper.overload_params(**kwargs)

This method adds query parameters. As its name suggests, it will not update existing keys, but instead add new values for the existing parameters. Here is a simple example:

u = UrlHelper('/foo')
u.overload_params(bar=1)  # /foo?bar=1
u.overload_params(bar=2)  # /foo?bar=1&bar=2

UrlHelper.toggle_params(**kwargs)

This method adds or removes query parameters depending on whether they already exist. It looks for both a matching parameter and value, and adds new parameters using UrlHelper.overload_params. Here is a simple example:

u = UrlHelper('/foo')
u.toggle_params(bar=1)  # /foo?bar=1
u.toggle_params(bar=1, foo=2)  # /foo?foo=2
u.toggle_params(bar=1, bar=2)  # /foo?bar=1&bar=2&foo=2

UrlHelper.get_path()

Returns the UrlHelper.path property. This method exist to help customization of UrlHelper.get_full_path() method in subclasses. Other than that, it's the same as using the path property.

UrlHelper.get_full_path(**kwargs)

Returns the full path with query string and fragment identifier (if any). The keyword arguments passed to this function are passed onto UrlHelper.get_query_string() method, and therefore to QueryDict.urlencode() method.

UrlHelper.get_full_quoted_path(**kwargs)

Same as UrlHelper.get_full_path() method, but returns the full path quoted so that it can be used as an URL parameter value.

UrlHelper.del_param(param)

Delete a single query parameter.

u = UrlHelper('/foo?bar=1&baz=2')
u.del_param('baz')
u.get_full_path() # returns '/foo?bar=1'

UrlHelper.del_params(*params, **kwargs)

Delete multiple parameters. If no parameters are specified, _all_ parameters are removed. You can also specify a set of key-value pairs to remove specific parameters with specified _values_. Here are a few examples:

u = UrlHelper('/foo?bar=1&baz=2&foo=3')
u.del_params('foo', 'bar')
u.get_full_path() # returns '/foo?baz=2'

u = UrlHelper('/foo?bar=1&baz=2&foo=3')
u.del_params()
u.get_full_path() # returns '/foo'

u = UrlHelper('/foo?bar=1&bar=2')
u.del_params(bar=2)
u.get_full_path() # returns '/foo?bar=1'

ContextProcessors

current_url

The current_url context processor will add a new variable to the template's context. This variable is called current_url, and it's an UrlHelper instance. Therefore, this variable has all the properties and methods of the UrlHelper class. For instance, if we are currently on /foo/bar?baz=1 path, you can do the following in a template:

{{ current_url.query_string }} {# renders `baz=1` #}
{{ current_url.get_path }} {# renders `/foo/bar` #}

and so on. The variable itself renders as full relative path with query string and fragment identifier (identical to output of UrlHelper.get_full_path() method).

Template tags

To use the template tags, first load the urls library:

{% load urls %}

URL tools currently has only one template tag, which is an assignment tag.

{% add_params %}

This template tag outputs a path with query string parameters given as keyword arguments. For instance, if we are on a page at /foo, we can use this tag:

{% add_params request.get_full_path foo='bar' %}

and the output would be:

/foo?foo=bar

Existing URL parameters are overridden by the ones specified as keyword arguments.

{% overload_params %}

Similar to {% add_params %} tag, except that it does not update existing parameters but overloads them with new values. For example, if we are on a page at /foo?bar=1, we can use this tag like so:

{% overload_params request.get_full_path bar=2 %}

and the output would be:

/foo?bar=1&bar=2

{% del_params %}

This tag outputs a path stripped of specified parameters, or all query parameters if none are specified. If you use keyword arguments, only the specified name-value pairs will be removed.

For example, if we are on the /foo?bar=1&bar=2&baz=2 URL:

{% del_param request.get_full_path 'bar' %}

outputs:

/foo?baz=2

and

{% del_params request.get_full_path %}

outputs:

/foo

Finally:

{% del_params request.get_full_path bar=2 %}

outputs:

/foo?bar=1&baz=2

{% toggle_params %}

This tag adds or removes parameters, depending on whether the parameter and value exists. For example, if we are on a page at /foo?bar=1, we can toggle the state of bar=1 using:

{% toggle_params request.get_full_path bar=1 %}

and the output would be:

/foo

If we are on a page at /foo, then the output of would be:

/foo?bar=1

Multiple parameters and values can be used. For example, on a page at /foo?bar=1&foo=2, parameters can be toggled like this:

{% toggle_params request.get_full_path bar=3 foo=2 foo=3 %}

To give:

/foo?bar=1&bar=3&foo=3

{% url_params %}

This tag is used as an assignment tag. Its first argument is an URL, followed by any number of keyword arguments that represent the URL parameters. For example, if we are requesting a page on '/foo' path, and do this:

{% url_params request.get_full_path foo='bar' as new_url %}

We can use the new_url variable from that point on, that represents the /foo?foo=bar URL. To use this with your configured URLs, you can use the built-in url tag:

{% url 'foo' as foo_url %}
{% url_arams foo_url foo='bar' as foo_url %}

If the reverse match for 'foo' is, say, '/foo', then the foo_url variable will, predictably, contain '/foo?foo=bar'.

This tag will override existing parameters rather than adding new values for existing keywords. Therefore, you can safely use it to set URL parameters whether they exist or not. This is typically useful when you are building URLs for controls like pagers. Regardless of whether there is a page parameter or not, setting it with url_params tag will correctly set the parameter to desired value:

{% url_params current_url page=2 %}
{# this works for both ``/foo?page=1`` and just ``/foo`` #}

Template filters

URL tools also include filters for manipulating data that will be used as part of URLs. To use them, you need to load the urls library first:

{% load urls %}

quote

The quote filter quotes URL parameters. It accepts optional safe characters that can be used to prevent quoting of certain characters. This filter uses urllib.quote for quoting. Safe characters inlude only the slash / by default.

{{ value|quote:"~/" }}

quote_plus

The quote_plus filter is similart ot the quote filter, except that it converts all spaces to +. This filter also takes optional safe characters. The filter uses urllib.quote_plus for quoting.

{{ value|quote_plus }}

Reporting bugs

Please report any bugs to our BitBucket issue tracker.

Contributors

We thank the following contributors:

  • nlaurance for contributing the overload_params and improvements to del_params, as well as compatibility with Django 1.4.x.
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