CORS - 使用 AJAX 在 Python (webapp2) Web 服务上发布 [英] CORS - Using AJAX to post on a Python (webapp2) web service

问题描述

这会很长:

好的，所以我正在开发一个 google 日历小工具，它将请求发送到托管在 Google App Engine 上的 Python webapp2 REST api.

Ok so I'm developing a google calendar gadget which sends requests to a Python webapp2 REST api hosted on Google App Engine.

当我尝试发布由于 CORS 而不允许我发布的内容时，问题就出现了.在 Chromes 的 DevTools 中，它说:

The problem comes when I try to POST something it doesn't allows me because of CORS. In Chromes' DevTools it says:

Method: OPTIONS.

Status: (failed) Request header field Content-Type is not allowed by Access-Control-Allow-Headers.

Origin https://hq34i4geprnp5vci191ljfuhcoerscl4-a-calendar-opensocial.googleusercontent.com is not allowed by Access-Control-Allow-Origin. 

我知道这是因为 CORS.这里:

I'm aware that this is because of CORS. Here:

Ajax - 'Origin localhost is not由 Access-Control-Allow-Origin 允许'

它说我必须添加

Access-Control-Allow-Origin: *

对于标题，但是我又是 ajax 的新手，我想知道它是否是这样完成的:

To the headers, but then again I'm new to ajax and I wonder if it's done this way:

    $.ajax({
        type: "POST",
        url: "https://myapp.appspot.com/service",
        contentType: "application/json; charset=utf-8",
        data: data,
        beforeSend: function (request)
        {
            request.setRequestHeader("Access-Control-Allow-Origin", "*");
        }
        success: function(data) {
              alert("AJAX done");
        }
    });

添加这个标题，输出不同(这让我想知道是否允许来源，虽然我真的不知道):

Adding this headers the output is different (which makes me wonder if the origin has been allowed, though I don't really know):

Method: OPTIONS.

Status: (failed) Request header field Content-Type is not allowed by Access-Control-Allow-Headers.

XMLHttpRequest cannot load https://myapp.appspot.com/service. Request header field Access-Control-Allow-Origin is not allowed by Access-Control-Allow-Headers. 

我什至发现了这个:

http://james.padolsey.com/javascript/cross-domain-requests-with-jquery/

这让我可以做 GET 请求，但我想学习如何在没有这个的情况下做它们.

Which lets me do GET requests, but I'd like to learn how to do them without this.

也在我的网络服务器上有这个:

Also on my webserver I have this:

...
    class webService(webapp2.RequestHandler):
         options(self):
               self.response.write('options')

         post(self):
               self.response.write('post')

    application = webapp2.WSGIApplication([
        ('/', MainPage),
        ('/service', webService)
    ], debug=True)

我不知道我是否必须向网络服务器添加更多内容，也没有找到信息说我必须这样做.此外，我认为我已接近实现 CORS 请求，但是，我找不到解释这一切的示例.

I don't know if I must add something more to the webserver, nor I've found info saying that I have to. Also I think I'm near to achieve the CORS request but, I can't find THE Example that explains it all.

请帮忙.

推荐答案

好的，我修好了.

首先我意识到这里 标头是由服务器发送的，所以在 AJAX 请求中发送这些标头时我做错了.

First of all I realized here that the headers were sent by the server so I was doing wrong when sending those headers in the AJAX request.

最后，在万维网上搜索之后，我找到了我所缺少的东西.这是愚蠢的事情.我找到了解决所有问题的页面:

Finally, after searching around the worldwide web I found what I was missing. It was something stupid. I found the page that fixed it all:

http://enable-cors.org/server_appengine.html

所以最后一切看起来像这样:

So finally everything looks like this:

$.ajax({
    type: "POST",
    url: "https://myapp.appspot.com/service",
    contentType: "application/json; charset=utf-8",
    data: data,
    success: function(data) {
        alert("AJAX done");
    }
});  

在 webService 中:

And in the webService:

class webService(webapp2.RequestHandler):

    def get(self):      
        self.response.headers.add_header('Access-Control-Allow-Origin', '*')
        self.response.headers['Content-Type'] = 'application/json'
        # do something

    def post(self):     
        self.response.headers.add_header('Access-Control-Allow-Origin', '*')
        self.response.headers['Content-Type'] = 'application/json'
        # do something

    def options(self):      
        self.response.headers['Access-Control-Allow-Origin'] = '*'
        self.response.headers['Access-Control-Allow-Headers'] = 'Origin, X-Requested-With, Content-Type, Accept'
        self.response.headers['Access-Control-Allow-Methods'] = 'POST, GET, PUT, DELETE'

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