angularjs-$http.post请求标头字段Access-Control-Allow-Headers

我正在使用Ionic Framework开发应用程序.

在后端,我为api编写了Flask应用程序,如下所示：

@API.route("/saverez",methods=["POST","OPTIONS"])
@crossdomain(origin='*',headers="*",methods="*")   
@render_api
def saver():
 .....

将json发布到api时出现错误.

var headers = {
                    'Access-Control-Allow-Origin' : '*','Access-Control-Allow-Methods' : 'POST,GET,OPTIONS','Accept': 'application/json'
                };

                $http({
                    method: "POST",headers: headers,url: url+ '/api/saverez',data: $scope.form
                }).success(function (result) 
                    console.log(result);
                }).error(function (data,status,headers,config) {
                    console.log(data);
                    console.log(status);
                    console.log(headers);
                    console.log(config);
                });

所以这给了我错误：

XMLHttpRequest cannot load http://myurl/api/saverez. Request header field Access-Control-Allow-Origin is not allowed by Access-Control-Allow-Headers. 

我用谷歌搜索,然后发现以下代码片段：

http://flask.pocoo.org/snippets/56/

我还将标题添加到我的nginx conf中,如下所示：

location ~* .(eot|ttf|woff)${
    add_header Access-Control-Allow-Origin *;
}

尝试了该文档中的所有内容以及我在Google上发现的所有东西,但可惜它没有任何好处.

如何为所有来源设置正确的标题？我也使用google pagespeed是否会导致此问题？

提前致谢.

-编辑-
Chrome网络输出

Remote Address:myip
Request URL:http://myurl/api/saverez
Request Method:OPTIONS
Status Code:200 OK
Request Headersview source
Accept:*/*
Accept-Encoding:gzip,deflate,sdch
Accept-Language:en-US,en;q=0.8
Access-Control-Request-Headers:access-control-allow-origin,accept,access-control-allow-methods,content-type
Access-Control-Request-Method:POST
Cache-Control:no-cache
Connection:keep-alive
Host:myurl
Origin:http://192.168.1.46:8100
Pragma:no-cache
Referer:http://192.168.1.46:8100/
User-Agent:Mozilla/5.0 (iPhone; CPU iPhone OS 7_0 like Mac OS X; en-us) AppleWebKit/537.51.1 (KHTML,like Gecko) Version/7.0 Mobile/11A465 Safari/9537.53
Response Headersview source
Access-Control-Allow-Credentials:true
Access-Control-Allow-Headers:*
Access-Control-Allow-Methods:*
Access-Control-Allow-Origin:*
Access-Control-Max-Age:21600
Allow:POST,OPTIONS
Content-Length:0
Content-Type:text/html; charset=utf-8
Date:Thu,28 Aug 2014 13:26:11 GMT
Server:nginx/1.6.0