解决Python3.6，发送POST请求错误提示：POST data should be bytes, an iterable of bytes, or a file object. It canno

之前遇到的坑，今天又遇到了，在此记录一下，

爬虫时，转码data时，出现下面错误信息：

POST data should be bytes, an iterable of bytes, or a file object. It cannot be of type str.

测试代码：

# -*- coding:utf-8 -*-

import urllib.request

def movieSpider():
    """
        模拟Ajax请求

    """

    url = "https://movie.douban.com/j/chart/top_list?"

    header = {"User-Agent" : "Opera/9.80 (Windows NT 6.1; U; en) Presto/2.7.62 Version/11.01"}

    formData = {
            "type" : "11",
            "interval_id" : "100:90",
            "action" : "",
            "start" : "0",
            "limit" : "20"
        }

    data = urllib.parse.urlencode(formData)

    request = urllib.request.Request(url, data=data, headers=header)

    print(url)
    print(data)

    print(urllib.request.urlopen(request).read())

if __name__ == "__main__":
    movieSpider()

报错截图：

查看源文档：https://docs.python.org/3/library/urllib.parse.html

Convert a mapping object or a sequence of two-element tuples, which may contain str or bytes objects, to a percent-encoded ASCII text string. If the resultant string is to be used as a data for POST operation with the urlopen() function, then it should be encoded to bytes, otherwise it would result in a TypeError.

简洁明了一句话，转码为bytes类型

修改代码如下：

# -*- coding:utf-8 -*-

import urllib.request

def movieSpider():
    """
        模拟Ajax请求

    """

    url = "https://movie.douban.com/j/chart/top_list?"

    header = {"User-Agent" : "Opera/9.80 (Windows NT 6.1; U; en) Presto/2.7.62 Version/11.01"}

    formData = {
            "type" : "11",
            "interval_id" : "100:90",
            "action" : "",
            "start" : "0",
            "limit" : "20"
        }
	
    #将str类型转换为bytes类型
    data = urllib.parse.urlencode(formData).encode("utf-8")

    request = urllib.request.Request(url, data=data, headers=header)

    print(urllib.request.urlopen(request).read().decode("utf-8"))

if __name__ == "__main__":
    movieSpider()

测试结果(部分截图)：

总结：

多看源文档少踩坑