如何通过继承对 python 中的请求进行子类化

Question

我想专门化/子class请求包以添加一些具有自定义功能的方法。

我试过这样做：

# concrete_requests.py
import requests

class concreteRequests(requests):
    def __init__(self):
        super(concreteRequests, self).__init__() 
        self.session()

    def login(self):
        payload = {'user': 'foo', 'pass': 'bar'}
        self.get('loginUrl', headers=header, data=payload)
        # more login stuff...

# my_class.py
class MyClass:
    def __init__():
        self.requests = concreteRequests()
        self.requests.login()

这样我仍然可以受益于 self.requests 成员 + 我的具体实施。所以我可以这样做：self.requests.get(...) 或 print(self.requests.post(...).status_code) 等等。

我猜这行 super(concreteRequests, self).__init__() 可能毫无用处，因为 requests 中没有任何 class 声明，只是导入...

那么，requests包可以subclassed/specialized通过继承吗？

Answer 1

requests 是 python 模块而不是 class。你只能子class classes.

所以基本上你应该在你自己的内部利用它的 methods/functions 自定义 class.

import requests

class MyRequests:
    def __init__(self, username, passwd):
        self.username = username
        self.passwd = passwd

    def get(self, *args, **kwargs):
        # do your thing
        resp = requests.get(...)
        # do more processing

我上面写的只是一个让你开始的例子。

Answer 2

我想给你一个完整的例子：

    # ----example.py----
    from locust import HttpUser, task, between
    import requests

    # Create fake api endpoint POST https://mocki.io/fake-json-api 
    class MyClient():
        def __init__(self, host):
            self.session = requests.session()
            self.host = host

        def create_user(self, *args, **kwargs):
            return self.session.post('{}/v1/9b021e1a'.format(self.host), json={"name":"something"})

    class QuickstartUser(HttpUser):
        wait_time = between(1, 2)

        @task
        def api(self):
            my_client = MyClient('https://api.mocki.io')
            my_client.session = self.client
            print(my_client.create_user().status_code)

    print('Executing client normally')
    client = MyClient('https://api.mocki.io')
    print(client.create_user().status_code)

您可以执行客户端代码：

python example.py

你可以用locust执行客户端：

locust --host https://api.mocki.io --users 5 --spawn-rate 1 --locustfile example.py

在两次执行中，您使用的是同一个客户端。

Answer 3

一个好的方法是从请求中继承 Session object。一个基本的例子：

from requests import Session

class MyClient(Session):
    """Specialized client that inherits the requests api."""
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

    def get_google(self):
        return self.get("http://google.com")

MyClient 免费包含 Session (request) api，以及您想要添加的任何其他内容。

A real-world 示例：假设客户端需要在运行时指定的身份验证 header（在这种情况下，身份验证需要当前时间戳）。这是一个子类 Session 和子类 AuthBase 的示例客户端，它实现了这一点（此代码需要为 api_key、secret_key、密码短语设置值）：

import json, hmac, hashlib, time, requests, base64
from requests.auth import AuthBase
from requests import Session

class MyClient(Session):
    """Client with specialized auth required by api."""
    def __init__(self, api_key, secret_key, passphrase, *args, **kwargs):
        # allow passing args to `Session.__init__`
        super().__init__(*args, **kwargs)
        
        # `self.auth` callable that creates timestamp when request is made
        self.auth = MyAuth(api_key, secret_key, passphrase)


class MyAuth(AuthBase):
    """Auth includes current timestamp when called.
       https://docs.python-requests.org/en/master/user/advanced/#custom-authentication    
    """

    def __init__(self, api_key, secret_key, passphrase):
        self.api_key = api_key
        self.secret_key = secret_key
        self.passphrase = passphrase

    def __call__(self, request):

        timestamp = str(time.time())
        message = timestamp + request.method + request.path_url + (request.body or "")
        message = message.encode("utf-8")
        hmac_key = base64.b64decode(self.secret_key)
        signature = hmac.new(hmac_key, message, hashlib.sha256)
        signature_b64 = base64.b64encode(signature.digest())
        request.headers.update(
            {
                "ACCESS-SIGN": signature_b64,
                "ACCESS-TIMESTAMP": timestamp,
                "ACCESS-KEY": self.api_key,
                "ACCESS-PASSPHRASE": self.passphrase,
                "Content-Type": "application/json",
            }
        )
        return request

如何通过继承对 python 中的请求进行子类化

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