rana-cli/wakatime/packages/requests/docs/user/quickstart.rst

.. _quickstart:

Quickstart
==========

.. module:: requests.models

Eager to get started? This page gives a good introduction in how to get started
with Requests.

First, make sure that:

* Requests is :ref:`installed <install>`
* Requests is :ref:`up-to-date <updates>`


Let's get started with some simple examples.


Make a Request
--------------

Making a request with Requests is very simple.

Begin by importing the Requests module::

    >>> import requests

Now, let's try to get a webpage. For this example, let's get GitHub's public
timeline ::

    >>> r = requests.get('https://api.github.com/events')

Now, we have a :class:`Response <requests.Response>` object called ``r``. We can
get all the information we need from this object.

Requests' simple API means that all forms of HTTP request are as obvious. For
example, this is how you make an HTTP POST request::

    >>> r = requests.post("http://httpbin.org/post")

Nice, right? What about the other HTTP request types: PUT, DELETE, HEAD and
OPTIONS? These are all just as simple::

    >>> r = requests.put("http://httpbin.org/put")
    >>> r = requests.delete("http://httpbin.org/delete")
    >>> r = requests.head("http://httpbin.org/get")
    >>> r = requests.options("http://httpbin.org/get")

That's all well and good, but it's also only the start of what Requests can
do.


Passing Parameters In URLs
--------------------------

You often want to send some sort of data in the URL's query string. If
you were constructing the URL by hand, this data would be given as key/value
pairs in the URL after a question mark, e.g. ``httpbin.org/get?key=val``.
Requests allows you to provide these arguments as a dictionary, using the
``params`` keyword argument. As an example, if you wanted to pass
``key1=value1`` and ``key2=value2`` to ``httpbin.org/get``, you would use the
following code::

    >>> payload = {'key1': 'value1', 'key2': 'value2'}
    >>> r = requests.get("http://httpbin.org/get", params=payload)

You can see that the URL has been correctly encoded by printing the URL::

    >>> print(r.url)
    http://httpbin.org/get?key2=value2&key1=value1

Note that any dictionary key whose value is ``None`` will not be added to the
URL's query string.

In order to pass a list of items as a value you must mark the key as
referring to a list like string by appending ``[]`` to the key::

    >>> payload = {'key1': 'value1', 'key2[]': ['value2', 'value3']}
    >>> r = requests.get("http://httpbin.org/get", params=payload)
    >>> print(r.url)
    http://httpbin.org/get?key1=value1&key2%5B%5D=value2&key2%5B%5D=value3

Response Content
----------------

We can read the content of the server's response. Consider the GitHub timeline
again::

    >>> import requests
    >>> r = requests.get('https://api.github.com/events')
    >>> r.text
    u'[{"repository":{"open_issues":0,"url":"https://github.com/...

Requests will automatically decode content from the server. Most unicode
charsets are seamlessly decoded.

When you make a request, Requests makes educated guesses about the encoding of
the response based on the HTTP headers. The text encoding guessed by Requests
is used when you access ``r.text``. You can find out what encoding Requests is
using, and change it, using the ``r.encoding`` property::

    >>> r.encoding
    'utf-8'
    >>> r.encoding = 'ISO-8859-1'

If you change the encoding, Requests will use the new value of ``r.encoding``
whenever you call ``r.text``. You might want to do this in any situation where
you can apply special logic to work out what the encoding of the content will
be. For example, HTTP and XML have the ability to specify their encoding in
their body. In situations like this, you should use ``r.content`` to find the
encoding, and then set ``r.encoding``. This will let you use ``r.text`` with
the correct encoding.

Requests will also use custom encodings in the event that you need them. If
you have created your own encoding and registered it with the ``codecs``
module, you can simply use the codec name as the value of ``r.encoding`` and
Requests will handle the decoding for you.

Binary Response Content
-----------------------

You can also access the response body as bytes, for non-text requests::

    >>> r.content
    b'[{"repository":{"open_issues":0,"url":"https://github.com/...

The ``gzip`` and ``deflate`` transfer-encodings are automatically decoded for you.

For example, to create an image from binary data returned by a request, you can
use the following code::

    >>> from PIL import Image
    >>> from StringIO import StringIO
    >>> i = Image.open(StringIO(r.content))


JSON Response Content
---------------------

There's also a builtin JSON decoder, in case you're dealing with JSON data::

    >>> import requests
    >>> r = requests.get('https://api.github.com/events')
    >>> r.json()
    [{u'repository': {u'open_issues': 0, u'url': 'https://github.com/...

In case the JSON decoding fails, ``r.json`` raises an exception. For example, if
the response gets a 401 (Unauthorized), attempting ``r.json`` raises ``ValueError:
No JSON object could be decoded``


Raw Response Content
--------------------

In the rare case that you'd like to get the raw socket response from the
server, you can access ``r.raw``. If you want to do this, make sure you set
``stream=True`` in your initial request. Once you do, you can do this::

    >>> r = requests.get('https://api.github.com/events', stream=True)
    >>> r.raw
    <requests.packages.urllib3.response.HTTPResponse object at 0x101194810>
    >>> r.raw.read(10)
    '\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\x03'

In general, however, you should use a pattern like this to save what is being
streamed to a file::

    with open(filename, 'wb') as fd:
        for chunk in r.iter_content(chunk_size):
            fd.write(chunk)

Using ``Response.iter_content`` will handle a lot of what you would otherwise
have to handle when using ``Response.raw`` directly. When streaming a
download, the above is the preferred and recommended way to retrieve the
content.


Custom Headers
--------------

If you'd like to add HTTP headers to a request, simply pass in a ``dict`` to the
``headers`` parameter.

For example, we didn't specify our content-type in the previous example::

    >>> import json
    >>> url = 'https://api.github.com/some/endpoint'
    >>> payload = {'some': 'data'}
    >>> headers = {'content-type': 'application/json'}

    >>> r = requests.post(url, data=json.dumps(payload), headers=headers)


More complicated POST requests
------------------------------

Typically, you want to send some form-encoded data — much like an HTML form.
To do this, simply pass a dictionary to the ``data`` argument. Your
dictionary of data will automatically be form-encoded when the request is made::

    >>> payload = {'key1': 'value1', 'key2': 'value2'}
    >>> r = requests.post("http://httpbin.org/post", data=payload)
    >>> print(r.text)
    {
      ...
      "form": {
        "key2": "value2",
        "key1": "value1"
      },
      ...
    }

There are many times that you want to send data that is not form-encoded. If
you pass in a ``string`` instead of a ``dict``, that data will be posted directly.

For example, the GitHub API v3 accepts JSON-Encoded POST/PATCH data::

    >>> import json
    >>> url = 'https://api.github.com/some/endpoint'
    >>> payload = {'some': 'data'}

    >>> r = requests.post(url, data=json.dumps(payload))


POST a Multipart-Encoded File
-----------------------------

Requests makes it simple to upload Multipart-encoded files::

    >>> url = 'http://httpbin.org/post'
    >>> files = {'file': open('report.xls', 'rb')}

    >>> r = requests.post(url, files=files)
    >>> r.text
    {
      ...
      "files": {
        "file": "<censored...binary...data>"
      },
      ...
    }

You can set the filename, content_type and headers explicitly:

    >>> url = 'http://httpbin.org/post'
    >>> files = {'file': ('report.xls', open('report.xls', 'rb'), 'application/vnd.ms-excel', {'Expires': '0'})}

    >>> r = requests.post(url, files=files)
    >>> r.text
    {
      ...
      "files": {
        "file": "<censored...binary...data>"
      },
      ...
    }

If you want, you can send strings to be received as files::

    >>> url = 'http://httpbin.org/post'
    >>> files = {'file': ('report.csv', 'some,data,to,send\nanother,row,to,send\n')}

    >>> r = requests.post(url, files=files)
    >>> r.text
    {
      ...
      "files": {
        "file": "some,data,to,send\\nanother,row,to,send\\n"
      },
      ...
    }

In the event you are posting a very large file as a ``multipart/form-data``
request, you may want to stream the request. By default, ``requests`` does not
support this, but there is a separate package which does -
``requests-toolbelt``. You should read `the toolbelt's documentation
<https://toolbelt.readthedocs.org>`_ for more details about how to use it.

For sending multiple files in one request refer to the :ref:`advanced <advanced>`
section.


Response Status Codes
---------------------

We can check the response status code::

    >>> r = requests.get('http://httpbin.org/get')
    >>> r.status_code
    200

Requests also comes with a built-in status code lookup object for easy
reference::

    >>> r.status_code == requests.codes.ok
    True

If we made a bad request (a 4XX client error or 5XX server error response), we
can raise it with
:meth:`Response.raise_for_status() <requests.Response.raise_for_status>`::

    >>> bad_r = requests.get('http://httpbin.org/status/404')
    >>> bad_r.status_code
    404

    >>> bad_r.raise_for_status()
    Traceback (most recent call last):
      File "requests/models.py", line 832, in raise_for_status
        raise http_error
    requests.exceptions.HTTPError: 404 Client Error

But, since our ``status_code`` for ``r`` was ``200``, when we call
``raise_for_status()`` we get::

    >>> r.raise_for_status()
    None

All is well.


Response Headers
----------------

We can view the server's response headers using a Python dictionary::

    >>> r.headers
    {
        'content-encoding': 'gzip',
        'transfer-encoding': 'chunked',
        'connection': 'close',
        'server': 'nginx/1.0.4',
        'x-runtime': '148ms',
        'etag': '"e1ca502697e5c9317743dc078f67693f"',
        'content-type': 'application/json'
    }

The dictionary is special, though: it's made just for HTTP headers. According to
`RFC 7230 <http://tools.ietf.org/html/rfc7230#section-3.2>`_, HTTP Header names
are case-insensitive.

So, we can access the headers using any capitalization we want::

    >>> r.headers['Content-Type']
    'application/json'

    >>> r.headers.get('content-type')
    'application/json'


Cookies
-------

If a response contains some Cookies, you can quickly access them::

    >>> url = 'http://example.com/some/cookie/setting/url'
    >>> r = requests.get(url)

    >>> r.cookies['example_cookie_name']
    'example_cookie_value'

To send your own cookies to the server, you can use the ``cookies``
parameter::

    >>> url = 'http://httpbin.org/cookies'
    >>> cookies = dict(cookies_are='working')

    >>> r = requests.get(url, cookies=cookies)
    >>> r.text
    '{"cookies": {"cookies_are": "working"}}'


Redirection and History
-----------------------

By default Requests will perform location redirection for all verbs except
HEAD.

We can use the ``history`` property of the Response object to track redirection.

The :meth:`Response.history <requests.Response.history>` list contains the
:class:`Response <requests.Response>` objects that were created in order to
complete the request. The list is sorted from the oldest to the most recent
response.

For example, GitHub redirects all HTTP requests to HTTPS::

    >>> r = requests.get('http://github.com')
    >>> r.url
    'https://github.com/'
    >>> r.status_code
    200
    >>> r.history
    [<Response [301]>]


If you're using GET, OPTIONS, POST, PUT, PATCH or DELETE, you can disable
redirection handling with the ``allow_redirects`` parameter::

    >>> r = requests.get('http://github.com', allow_redirects=False)
    >>> r.status_code
    301
    >>> r.history
    []

If you're using HEAD, you can enable redirection as well::

    >>> r = requests.head('http://github.com', allow_redirects=True)
    >>> r.url
    'https://github.com/'
    >>> r.history
    [<Response [301]>]


Timeouts
--------

You can tell Requests to stop waiting for a response after a given number of
seconds with the ``timeout`` parameter::

    >>> requests.get('http://github.com', timeout=0.001)
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
    requests.exceptions.Timeout: HTTPConnectionPool(host='github.com', port=80): Request timed out. (timeout=0.001)


.. admonition:: Note

    ``timeout`` is not a time limit on the entire response download;
    rather, an exception is raised if the server has not issued a
    response for ``timeout`` seconds (more precisely, if no bytes have been
    received on the underlying socket for ``timeout`` seconds).


Errors and Exceptions
---------------------

In the event of a network problem (e.g. DNS failure, refused connection, etc),
Requests will raise a :class:`~requests.exceptions.ConnectionError` exception.

In the rare event of an invalid HTTP response, Requests will raise an
:class:`~requests.exceptions.HTTPError` exception.

If a request times out, a :class:`~requests.exceptions.Timeout` exception is
raised.

If a request exceeds the configured number of maximum redirections, a
:class:`~requests.exceptions.TooManyRedirects` exception is raised.

All exceptions that Requests explicitly raises inherit from
:class:`requests.exceptions.RequestException`.

-----------------------

Ready for more? Check out the :ref:`advanced <advanced>` section.