Python: confusions with urljoin

Question

I am trying to form URLs from different pieces, and having trouble understanding the behavior of this method. For example:

Python 3.x

from urllib.parse import urljoin

>>> urljoin('some', 'thing')
'thing'
>>> urljoin('http://some', 'thing')
'http://some/thing'
>>> urljoin('http://some/more', 'thing')
'http://some/thing'
>>> urljoin('http://some/more/', 'thing') # just a tad / after 'more'
'http://some/more/thing'
urljoin('http://some/more/', '/thing')
'http://some/thing'

Can you explain the exact behavior of this method?

Asked By: treecoder

||

Source

Answer 1

The best way (for me) to think of this is the first argument, base is like the page you are on in your browser. The second argument url is the href of an anchor on that page. The result is the final url to which you will be directed should you click.

>>> urljoin('some', 'thing')
'thing'

This one makes sense given my description. Though one would hope base includes a scheme and domain.

>>> urljoin('http://some', 'thing')
'http://some/thing'

If you are on a vhost some, and there is an anchor like <a href='thing'>Foo</a> then the link will take you to http://some/thing

>>> urljoin('http://some/more', 'thing')
'http://some/thing'

We are on some/more here, so a relative link of thing will take us to /some/thing

>>> urljoin('http://some/more/', 'thing') # just a tad / after 'more'
'http://some/more/thing'

Here, we aren’t on some/more, we are on some/more/ which is different. Now, our relative link will take us to some/more/thing

>>> urljoin('http://some/more/', '/thing')
'http://some/thing'

And lastly. If on some/more/ and the href is to /thing, you will be linked to some/thing.

Answered By: sberry

Answer 2

urllib.parse.urljoin(base, url)

If url is an absolute URL (that is, starting with //, http://, https://, …), the url’s host name and/or scheme will be present in the
result. For example:

>>> urljoin('https://www.google.com', '//www.microsoft.com')
'https://www.microsoft.com'
>>>

otherwise, urllib.parse.urljoin(base, url) will

Construct a full (“absolute”) URL by combining a “base URL” (base) with another URL (url). Informally, this uses components of the base
URL, in particular the addressing scheme, the network location and
(part of) the path, to provide missing components in the relative URL.

>>> urlparse('http://a/b/c/d/e')
ParseResult(scheme='http', netloc='a', path='/b/c/d/e', params='', query='', fragment='')
>>> urljoin('http://a/b/c/d/e', 'f')
>>>'http://a/b/c/d/f'
>>> urlparse('http://a/b/c/d/e/')
ParseResult(scheme='http', netloc='a', path='/b/c/d/e/', params='', query='', fragment='')
>>> urljoin('http://a/b/c/d/e/', 'f')
'http://a/b/c/d/e/f'
>>>

it grabs the path of the first parameter (base), strips the part after the last / and joins with the second parameter (url).

If url starts with /, it joins the scheme and netloc of base with url

>>>urljoin('http://a/b/c/d/e', '/f')
'http://a/f'

Answered By: Bar Horing Amir

Python: confusions with urljoin

Question:

Answers: