Python requests обработка ошибок

Make a Request¶

Making a request with Requests is very simple.

Begin by importing the Requests module:

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 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('https://httpbin.org/post', data={'key': 'value'})

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

>>> r = requests.put('https://httpbin.org/put', data={'key': 'value'})
>>> r = requests.delete('https://httpbin.org/delete')
>>> r = requests.head('https://httpbin.org/get')
>>> r = requests.options('https://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 of strings,
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('https://httpbin.org/get', params=payload)

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

>>> print(r.url)
https://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.

You can also pass a list of items as a value:

>>> payload = {'key1': 'value1', 'key2': ['value2', 'value3']}

>>> r = requests.get('https://httpbin.org/get', params=payload)
>>> print(r.url)
https://httpbin.org/get?key1=value1&key2=value2&key2=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
'[{"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, HTML 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.

The br transfer-encoding is automatically decoded for you if a Brotli library
like brotli or brotlicffi is installed.

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

>>> from PIL import Image
>>> from io import BytesIO

>>> i = Image.open(BytesIO(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()
[{'repository': {'open_issues': 0, 'url': 'https://github.com/...

In case the JSON decoding fails, r.json() raises an exception. For example, if
the response gets a 204 (No Content), or if the response contains invalid JSON,
attempting r.json() raises requests.exceptions.JSONDecodeError. This wrapper exception
provides interoperability for multiple exceptions that may be thrown by different
python versions and json serialization libraries.

It should be noted that the success of the call to r.json() does not
indicate the success of the response. Some servers may return a JSON object in a
failed response (e.g. error details with HTTP 500). Such JSON will be decoded
and returned. To check that a request is successful, use
r.raise_for_status() or check r.status_code is what you expect.

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
<urllib3.response.HTTPResponse object at 0x101194810>

>>> r.raw.read(10)
b'x1fx8bx08x00x00x00x00x00x00x03'

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=128):
        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. Note that chunk_size can be freely adjusted to a number that
may better fit your use cases.

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

The data argument can also have multiple values for each key. This can be
done by making data either a list of tuples or a dictionary with lists
as values. This is particularly useful when the form has multiple elements that
use the same key:

>>> payload_tuples = [('key1', 'value1'), ('key1', 'value2')]
>>> r1 = requests.post('https://httpbin.org/post', data=payload_tuples)
>>> payload_dict = {'key1': ['value1', 'value2']}
>>> r2 = requests.post('https://httpbin.org/post', data=payload_dict)
>>> print(r1.text)
{
  ...
  "form": {
    "key1": [
      "value1",
      "value2"
    ]
  },
  ...
}
>>> r1.text == r2.text
True

There are times that you may 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))

Please note that the above code will NOT add the Content-Type header
(so in particular it will NOT set it to application/json).

If you need that header set and you don’t want to encode the dict yourself,
you can also pass it directly using the json parameter (added in version 2.4.2)
and it will be encoded automatically:

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

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

Note, the json parameter is ignored if either data or files is passed.

POST a Multipart-Encoded File¶

Requests makes it simple to upload Multipart-encoded files:

>>> url = 'https://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 = 'https://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 = 'https://httpbin.org/post'
>>> files = {'file': ('report.csv', 'some,data,to,sendnanother,row,to,sendn')}

>>> 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 for more details about how to use it.

For sending multiple files in one request refer to the advanced
section.

Response Status Codes¶

We can check the response status code:

>>> r = requests.get('https://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
Response.raise_for_status():

>>> bad_r = requests.get('https://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.

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

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

Cookies are returned in a RequestsCookieJar,
which acts like a dict but also offers a more complete interface,
suitable for use over multiple domains or paths. Cookie jars can
also be passed in to requests:

>>> jar = requests.cookies.RequestsCookieJar()
>>> jar.set('tasty_cookie', 'yum', domain='httpbin.org', path='/cookies')
>>> jar.set('gross_cookie', 'blech', domain='httpbin.org', path='/elsewhere')
>>> url = 'https://httpbin.org/cookies'
>>> r = requests.get(url, cookies=jar)
>>> r.text
'{"cookies": {"tasty_cookie": "yum"}}'

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 Response.history list contains the
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. Nearly all production code should use
this parameter in nearly all requests. Failure to do so can cause your program
to hang indefinitely:

>>> requests.get('https://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)

Errors and Exceptions¶

In the event of a network problem (e.g. DNS failure, refused connection, etc),
Requests will raise a ConnectionError exception.

Response.raise_for_status() will
raise an HTTPError if the HTTP request
returned an unsuccessful status code.

If a request times out, a Timeout exception is
raised.

If a request exceeds the configured number of maximum redirections, a
TooManyRedirects exception is raised.

All exceptions that Requests explicitly raises inherit from
requests.exceptions.RequestException.

Ready for more? Check out the advanced section.

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