2014-12-04 62 views
1

我想定义一个http.Client,它自动将表单值附加到所有GET/POST请求。将表格值附加到GET/POST请求中去

我天真地尝试实施http.RoundTripper从另一个库复制/粘贴使用此技术来修改每个请求的标头。

type Transport struct { 
    // Transport is the HTTP transport to use when making requests. 
    // It will default to http.DefaultTransport if nil. 
    // (It should never be an oauth.Transport.) 
    Transport http.RoundTripper 
} 

// Client returns an *http.Client that makes OAuth-authenticated requests. 
func (t *Transport) Client() *http.Client { 
    return &http.Client{Transport: t} 
} 

func (t *Transport) transport() http.RoundTripper { 
    if t.Transport != nil { 
     return t.Transport 
    } 
    return http.DefaultTransport 
} 

func (t *Transport) RoundTrip(req *http.Request) (*http.Response, error) { 
    // To set the Authorization header, we must make a copy of the Request 
    // so that we don't modify the Request we were given. 
    // This is required by the specification of http.RoundTripper. 
    req = cloneRequest(req) 
>> req.Form.Set("foo", bar) 

    // Make the HTTP request. 
    return t.transport().RoundTrip(req) 
} 

// cloneRequest returns a clone of the provided *http.Request. 
// The clone is a shallow copy of the struct and its Header map. 
func cloneRequest(r *http.Request) *http.Request { 
    // shallow copy of the struct 
    r2 := new(http.Request) 
    *r2 = *r 
    // deep copy of the Header 
    r2.Header = make(http.Header) 
    for k, s := range r.Header { 
     r2.Header[k] = s 
    } 
    return r2 
} 

但是这不起作用。该req.Form值映射似乎并不在此阶段存在,所以我得到了恐慌: panic: runtime error: assignment to entry in nil map

我尝试添加该到(t *Transport) RoundTrip,但没有运气:

err := req.ParseForm() 
misc.PanicIf(err) 

我不知道我在做什么,有什么提示?

编辑:有是在试图cloneRequest方法复制req.Form值是没有意义的,因为r.Form是空的地图呢。

+0

是否要添加请求参数或修改表单主体? – JimB 2014-12-04 19:07:47

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@JimB我想将请求参数添加到每个请求。 – 2014-12-04 19:14:51

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但是当有'multipart/form-data'或'application/x-www-form-urlencoded'时你打算做什么?你还想要为url添加一个参数吗? – JimB 2014-12-04 19:24:14

回答

2

Form,PostFormParseForm()仅在接收请求时使用。在发送请求时,Transport希望数据被正确编码。

你有正确的想法,通过包装RoundTrip,但你必须自己处理编码的数据。

if req.URL.RawQuery == "" { 
    req.URL.RawQuery = "foo=bar" 
} else { 
    req.URL.RawQuery = req.URL.RawQuery + "&" + "foo=bar" 
} 

或者:

form, _ = url.ParseQuery(req.URL.RawQuery) 
form.Add("boo", "far") 
req.URL.RawQuery = form.Encode() 

您也可以选择检查url.Values提前,如果你想避免重复键。检查Content-Type标头为multipart/form-dataapplication/x-www-form-urlencoded以避免与其他类型的查询交互可能是一个好主意。

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工程就像一个魅力。我也处理了'content-type'。 – 2014-12-04 22:12:19