python-requests:获取响应内容的头部而不消耗它

问题描述

使用 python-requests 和 python-magic，我想测试一个网络资源的 mime 类型而不获取它的所有内容(特别是如果这个资源恰好是一个 ogg 文件或一个 PDF 文件).根据结果​​，我可能决定全部获取.但是，在测试了 mime 类型后调用 text 方法只会返回尚未消耗的内容.如何在不消耗响应内容的情况下测试 mime 类型?

Using python-requests and python-magic, I would like to test the mime-type of a web resource without fetching all its content (especially if this resource happens to be eg. an ogg file or a PDF file). Based on the result, I might decide to fetch it all. However calling the text method after having tested the mime-type only returns what hasn't been consumed yet. How could I test the mime-type without consuming the response content?

以下是我当前的代码.

import requests
import magic


r = requests.get("http://www.december.com/html/demo/hello.html", prefetch=False)
mime = magic.from_buffer(r.iter_content(256).next(), mime=True)

if mime == "text/html":
    print(r.text)  # I'd like r.text to give me the entire response content

谢谢！

推荐答案

注意:在问这个问题的时候，正确的方法是使用 预取=假.该选项已被重命名为 stream 并且布尔值被反转，因此您需要 stream=True.

Note: at the time this question was asked, the correct method to fetch only headers stream the body was to use prefetch=False. That option has since been renamed to stream and the boolean value is inverted, so you want stream=True.

原始答案如下.

一旦使用了iter_content()，就必须继续使用；.text 间接使用相同的接口(通过 .content).

Once you use iter_content(), you have to continue using it; .text indirectly uses the same interface under the hood (via .content).

换句话说，通过使用 iter_content()，您必须手动完成 .text 所做的工作:

In other words, by using iter_content() at all, you have to do the work .text does by hand:

from requests.compat import chardet

r = requests.get("http://www.december.com/html/demo/hello.html", prefetch=False)
peek = r.iter_content(256).next()
mime = magic.from_buffer(peek, mime=True)

if mime == "text/html":
    contents = peek + b''.join(r.iter_content(10 * 1024))
    encoding = r.encoding
    if encoding is None:
        # detect encoding
        encoding = chardet.detect(contents)['encoding']
    try:
        textcontent = str(contents, encoding, errors='replace')
    except (LookupError, TypeError):
        textcontent = str(contents, errors='replace')
    print(textcontent)

假设您使用 Python 3.

presuming you use Python 3.

另一种方法是发出 2 个请求:

The alternative is to make 2 requests:

r = requests.get("http://www.december.com/html/demo/hello.html", prefetch=False)
mime = magic.from_buffer(r.iter_content(256).next(), mime=True)

if mime == "text/html":
     print(r.requests.get("http://www.december.com/html/demo/hello.html").text)

Python 2 版本:

Python 2 version:

r = requests.get("http://www.december.com/html/demo/hello.html", prefetch=False)
peek = r.iter_content(256).next()
mime = magic.from_buffer(peek, mime=True)

if mime == "text/html":
    contents = peek + ''.join(r.iter_content(10 * 1024))
    encoding = r.encoding
    if encoding is None:
        # detect encoding
        encoding = chardet.detect(contents)['encoding']
    try:
        textcontent = unicode(contents, encoding, errors='replace')
    except (LookupError, TypeError):
        textcontent = unicode(contents, errors='replace')
    print(textcontent)

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