yarl¶

The module provides handy URL class for URL parsing and changing.

Introduction¶

URL is constructed from str:

>>> from yarl import URL
>>> url = URL('https://www.python.org/~guido?arg=1#frag')
>>> url
URL('https://www.python.org/~guido?arg=1#frag')

All URL parts: scheme, user, password, host, port, path, query and fragment are accessible by properties:

>>> url.scheme
'https'
>>> url.host
'www.python.org'
>>> url.path
'/~guido'
>>> url.query_string
'arg=1'
>>> url.query
<MultiDictProxy('arg': '1')>
>>> url.fragment
'frag'

All URL manipulations produces a new URL object:

>>> url.parent / 'downloads/source'
URL('https://www.python.org/downloads/source')

A URL object can be modified with / and % operators:

>>> url = URL('https://www.python.org')
>>> url / 'foo' / 'bar'
URL('https://www.python.org/foo/bar')
>>> url / 'foo' % {'bar': 'baz'}
URL('https://www.python.org/foo?bar=baz')

Strings passed to constructor and modification methods are automatically encoded giving canonical representation as result:

>>> url = URL('https://www.python.org/шлях')
>>> url
URL('https://www.python.org/%D1%88%D0%BB%D1%8F%D1%85')

Regular properties are percent-decoded, use raw_ versions for getting encoded strings:

>>> url.path
'/шлях'

>>> url.raw_path
'/%D1%88%D0%BB%D1%8F%D1%85'

Human readable representation of URL is available as human_repr():

>>> url.human_repr()
'https://www.python.org/шлях'

For full documentation please read Public API section.

Installation¶

$ pip install yarl

The library is Python 3 only!

PyPI contains binary wheels for Linux, Windows and MacOS. If you want to install yarl on another operating system (like Alpine Linux, which is not manylinux-compliant because of the missing glibc and therefore, cannot be used with our wheels) the the tarball will be used to compile the library from the source code. It requires a C compiler and and Python headers installed.

To skip the compilation you must explicitly opt-in by using a PEP 517 configuration setting pure-python, or setting the YARL_NO_EXTENSIONS environment variable to a non-empty value, e.g.:

$ pip install yarl --config-settings=pure-python=false

Please note that the pure-Python (uncompiled) version is much slower. However, PyPy always uses a pure-Python implementation, and, as such, it is unaffected by this variable.

Dependencies¶

yarl requires the multidict and propcache libraries.

It installs it automatically.

API documentation¶

Open Public API for reading full list of available methods.

Comparison with other URL libraries¶

furl (https://pypi.python.org/pypi/furl)

The library has a rich functionality but furl object is mutable.

I afraid to pass this object into foreign code: who knows if the code will modify my URL in a terrible way while I just want to send URL with handy helpers for accessing URL properties.

furl has other non obvious tricky things but the main objection is mutability.
URLObject (https://pypi.python.org/pypi/URLObject)

URLObject is immutable, that’s pretty good.

Every URL change generates a new URL object.

But the library doesn’t any decode/encode transformations leaving end user to cope with these gory details.

Why isn’t boolean supported by the URL query API?¶

There is no standard for boolean representation of boolean values.

Some systems prefer true/false, others like yes/no, on/off, Y/N, 1/0, etc.

yarl cannot make an unambiguous decision on how to serialize bool values because it is specific to how the end-user’s application is built and would be different for different apps. The library doesn’t accept booleans in the API; a user should convert bools into strings using own preferred translation protocol.