requsets之post

sign = 'd1462fde59f7674260b16630b0b1c791'
timestamp = '1602753947259'
token = 'ca24cce3e962f06134dd79d07c80b252'

def getallcoursecontent():
    url = 'http://api.XXXX.com/sys/coursepackagecontent/getallcoursecontent'
    headers = {
        'sign': sign,
        'timestamp': timestamp,
        'token': token,
        'Content-Type': 'application/json'
    }
    data = {
        'levelStage': '5',
        'pageIndex': '1',
        'pageSize': '10'
    }
    r = requests.post(url=url, headers=headers, data=data).text
    return print(r)
    
getallcoursecontent()

{"success":false,"code":"400","data":null,"message":"JSON解析异常","token":null,"encrypt":false,"timestamp":1602754020388}

我们加了content-type：application/json，但是返回结果却是JSON解析异常，我把数据拿去在线解析也没问题，但是为什么会这样呢？首先我们了解下content-type是什么

content-type：在Request Headers里表示请求和响应中的媒体类型信息，它用来告诉服务端如何处理请求的数据，以及告诉客户端（一般是浏览器）如何解析响应的数据，比如显示图片，解析并展示html等等。
常见的Content-Type：

• HTML文档标记：text/html;
• 普通ASCII文档标记：text/html;
• JPEG图片标记：image/jpeg;
• GIF图片标记：image/gif;
• js文档标记：application/javascript;
• xml文件标记：application/xml;

上面的Content-Type，我们只认得就好，但是下面有4种是需要我们清楚他们的区别及牢记在心的。

content-type:application/x-www-form-urlencoded
如果不指定content-type，则默认格式content-type:application/x-www-form-urlencoded
HTTP会将请求参数用key1=val1&key2=val2的方式进行组织，并放到请求实体里面，注意如果是中文或特殊字符如"/"、","、“:" 等会自动进行URL转码。不支持文件，一般用于表单提交。

content-type:multipart/form-data
与application/x-www-form-urlencoded不同，这是一个多部分多媒体类型。首先生成了一个 boundary 用于分割不同的字段，在请求实体里每个参数以------boundary开始，然后是附加信息和参数名，然后是空行，最后是参数内容。多个参数将会有多个boundary块。如果参数是文件会有特别的文件域。最后以------boundary–为结束标识。multipart/form-data支持文件上传的格式，一般需要上传文件的表单则用该类型。

content-type:application/json
JSON 是一种轻量级的数据格式，以“键-值”对的方式组织的数据。这个使用这个类型，需要参数本身就是json格式的数据，参数会被直接放到请求实体里，不进行任何处理。服务端/客户端会按json格式解析数据（约定好的情况下）。

content-type:application/xml 和 content-type:text/xml
与application/json类似，这里用的是xml格式的数据，text/xml的话，将忽略xml数据里的编码格式。

下面我们来看下接口文档

文档告诉我们次接口参数为json格式，但是要注意，如果开发没有特殊说明，则data参数加上content-type:application/json就可以请求成功
但是如果请求失败并报json解析异常时，你就要用到requests.post中的另一个参数：json

接口api：

def post(url, data=None, json=None, **kwargs):
    """Sends a POST request.

    :param url: URL for the new :class:`Request` object.
    :param data: (optional) Dictionary, bytes, or file-like object to send in the body of the :class:`Request`.
    :param json: (optional) json data to send in the body of the :class:`Request`.
    :param \*\*kwargs: Optional arguments that ``request`` takes.
    :return: :class:`Response <Response>` object
    :rtype: requests.Response
    """

    return request('post', url, data=data, json=json, **kwargs)

api明确告诉我们要在类的主体中发送的json数据时，可以用json参数

下面是使用json参数

def getallcoursecontent():
    url = 'http://api.XXXX.com/sys/coursepackagecontent/getallcoursecontent'
    headers = {
        'sign': sign,
        'timestamp': timestamp,
        'token': token
    }
    data = {
        'levelStage': '5',
        'pageIndex': '1',
        'pageSize': '10'
    }
    r = requests.post(url=url, headers=headers, json=data).text
    return print(r)

{"success":true,"code":"200","data":{"totalSize":20,"totalPage":2,"dataList":[{"classOutlineContent":"","classUrl":"","homeworkContent":"测试测试2","coverImageUrl":"","id":"1","sn":"1","courseLevelStage":"5"},{"classOutlineContent":"","classUrl":"","homeworkContent":"","coverImageUrl":"","id":"107","sn":"2","courseLevelStage":"5"},{"classOutlineContent":"","classUrl":"","homeworkContent":"","coverImageUrl":"","id":"108","sn":"3","courseLevelStage":"5"},{"classOutlineContent":"","classUrl":"","homeworkContent":"","coverImageUrl":"","id":"109","sn":"4","courseLevelStage":"5"},{"classOutlineContent":"","classUrl":"","homeworkContent":"","coverImageUrl":"","id":"110","sn":"5","courseLevelStage":"5"},{"classOutlineContent":"","classUrl":"","homeworkContent":"","coverImageUrl":"","id":"111","sn":"6","courseLevelStage":"5"},{"classOutlineContent":"","classUrl":"","homeworkContent":"","coverImageUrl":"","id":"112","sn":"7","courseLevelStage":"5"},{"classOutlineContent":"","classUrl":"","homeworkContent":"","coverImageUrl":"","id":"113","sn":"8","courseLevelStage":"5"},{"classOutlineContent":"","classUrl":"","homeworkContent":"","coverImageUrl":"","id":"114","sn":"9","courseLevelStage":"5"},{"classOutlineContent":"","classUrl":"","homeworkContent":"","coverImageUrl":"","id":"115","sn":"10","courseLevelStage":"5"}],"pageSize":10,"currentPage":1},"message":"请求成功","token":null,"encrypt":false,"timestamp":1602755473877}

总结：
最简单方法就是，使用post方法时data参数请求失败就使用json参数