小编alt*_*tab的帖子

我正在对成功的REST API进行http.patch调用(状态200),但并未返回所有响应头的键/值.我对ETag键/值很感兴趣.

这是一段代码:

let etag:number = 0;
let headers = new Headers();
headers.append('Content-Type', 'application/json');
headers.append('If-Match', String(etag));
this.http.patch(
    'http://example.com:9002/api/myresource/',
     JSON.stringify(dto),
     {headers: headers}
)   
.subscribe(
    (response:Response) => {
        let headers:Headers = response.headers;
        let etag:String = headers.get('ETag');
        console.log(etag);
    }
);

与REST客户端(邮递员)进行相同的调用时,响应头包含:

Content-Type: application/hal+json;charset=UTF-8
Date: Mon, 01 Feb 2016 05:21:09 GMT
ETag: "1"
Last-Modified: Mon, 01 Feb 2016 05:15:32 GMT
Server: Apache-Coyote/1.1
Transfer-Encoding: chunked
X-Application-Context: application:dev:9002

丢失的响应标头键/值是否为错误？可以通过配置解决问题吗？