mirror of https://github.com/python/cpython
158 lines
5.0 KiB
ReStructuredText
158 lines
5.0 KiB
ReStructuredText
:mod:`packaging.pypi.simple` --- Crawler using the PyPI "simple" interface
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==========================================================================
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.. module:: packaging.pypi.simple
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:synopsis: Crawler using the screen-scraping "simple" interface to fetch info
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and distributions.
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`packaging.pypi.simple` can process Python Package Indexes and provides
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useful information about distributions. It also can crawl local indexes, for
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instance.
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You should use `packaging.pypi.simple` for:
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* Search distributions by name and versions.
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* Process index external pages.
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* Download distributions by name and versions.
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And should not be used for:
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* Things that will end up in too long index processing (like "finding all
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distributions with a specific version, no matters the name")
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API
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---
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.. class:: Crawler
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Usage Exemples
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---------------
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To help you understand how using the `Crawler` class, here are some basic
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usages.
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Request the simple index to get a specific distribution
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Supposing you want to scan an index to get a list of distributions for
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the "foobar" project. You can use the "get_releases" method for that.
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The get_releases method will browse the project page, and return
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:class:`ReleaseInfo` objects for each found link that rely on downloads. ::
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>>> from packaging.pypi.simple import Crawler
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>>> crawler = Crawler()
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>>> crawler.get_releases("FooBar")
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[<ReleaseInfo "Foobar 1.1">, <ReleaseInfo "Foobar 1.2">]
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Note that you also can request the client about specific versions, using version
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specifiers (described in `PEP 345
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<http://www.python.org/dev/peps/pep-0345/#version-specifiers>`_)::
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>>> client.get_releases("FooBar < 1.2")
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[<ReleaseInfo "FooBar 1.1">, ]
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`get_releases` returns a list of :class:`ReleaseInfo`, but you also can get the
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best distribution that fullfil your requirements, using "get_release"::
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>>> client.get_release("FooBar < 1.2")
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<ReleaseInfo "FooBar 1.1">
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Download distributions
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^^^^^^^^^^^^^^^^^^^^^^
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As it can get the urls of distributions provided by PyPI, the `Crawler`
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client also can download the distributions and put it for you in a temporary
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destination::
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>>> client.download("foobar")
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/tmp/temp_dir/foobar-1.2.tar.gz
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You also can specify the directory you want to download to::
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>>> client.download("foobar", "/path/to/my/dir")
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/path/to/my/dir/foobar-1.2.tar.gz
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While downloading, the md5 of the archive will be checked, if not matches, it
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will try another time, then if fails again, raise `MD5HashDoesNotMatchError`.
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Internally, that's not the Crawler which download the distributions, but the
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`DistributionInfo` class. Please refer to this documentation for more details.
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Following PyPI external links
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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The default behavior for packaging is to *not* follow the links provided
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by HTML pages in the "simple index", to find distributions related
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downloads.
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It's possible to tell the PyPIClient to follow external links by setting the
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`follow_externals` attribute, on instantiation or after::
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>>> client = Crawler(follow_externals=True)
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or ::
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>>> client = Crawler()
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>>> client.follow_externals = True
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Working with external indexes, and mirrors
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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The default `Crawler` behavior is to rely on the Python Package index stored
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on PyPI (http://pypi.python.org/simple).
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As you can need to work with a local index, or private indexes, you can specify
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it using the index_url parameter::
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>>> client = Crawler(index_url="file://filesystem/path/")
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or ::
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>>> client = Crawler(index_url="http://some.specific.url/")
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You also can specify mirrors to fallback on in case the first index_url you
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provided doesnt respond, or not correctly. The default behavior for
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`Crawler` is to use the list provided by Python.org DNS records, as
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described in the :PEP:`381` about mirroring infrastructure.
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If you don't want to rely on these, you could specify the list of mirrors you
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want to try by specifying the `mirrors` attribute. It's a simple iterable::
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>>> mirrors = ["http://first.mirror","http://second.mirror"]
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>>> client = Crawler(mirrors=mirrors)
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Searching in the simple index
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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It's possible to search for projects with specific names in the package index.
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Assuming you want to find all projects containing the "distutils" keyword::
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>>> c.search_projects("distutils")
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[<Project "collective.recipe.distutils">, <Project "Distutils">, <Project
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"Packaging">, <Project "distutilscross">, <Project "lpdistutils">, <Project
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"taras.recipe.distutils">, <Project "zerokspot.recipe.distutils">]
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You can also search the projects starting with a specific text, or ending with
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that text, using a wildcard::
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>>> c.search_projects("distutils*")
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[<Project "Distutils">, <Project "Packaging">, <Project "distutilscross">]
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>>> c.search_projects("*distutils")
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[<Project "collective.recipe.distutils">, <Project "Distutils">, <Project
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"lpdistutils">, <Project "taras.recipe.distutils">, <Project
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"zerokspot.recipe.distutils">]
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