I have a reverse-proxy that returns body responses from a 3rd party API. This 3rd party API uses pagination, so my reverse-proxy path requires parameters for page number.
I'm having trouble using fmt.Sprint
to pass the parameter from the reverse-proxy URL to 3rd Party API request.
func (s *Server) getReverseProxy(w http.ResponseWriter, r *http.Request) {
keys, ok := r.URL.Query()["page"]
if !ok || len(keys[0]) < 1 {
log.Println("Url Param 'page' is missing")
return
}
// Query()["key"] will return an array of items,
// we only want the single item.
key := keys[0]
log.Println("Url Param 'page' is: " string(key))
// create http client to make GET request to reverse-proxy
client := &http.Client{}
// create 3rd party request
// creating this request is causing me the issue due to the page parameter
req, err := http.NewRequest("GET", fmt.Sprint("https://url.com/path?&page[size]=100&page[number]=%s\n", key), nil)
// more stuff down here but omitted for brevity.
}
Looking at the http.NewRequest
3rd party api request, the %s\n
part would be where they key
is passed for the page parameter
.
How can I correctly pass this variable to the url? In python what I'm looking to use is an f-string. Not sure im doing that correctly for Go.
EDIT: New implementation using url.Vaues()
func (s *Server) getReverseProxy(w http.ResponseWriter, r *http.Request) {
keys, ok := r.URL.Query()["page"]
if !ok || len(keys[0]) < 1 {
log.Println("Url Param 'page' is missing")
return
}
// Query()["key"] will return an array of items,
// we only want the single item.
key := keys[0]
log.Println("Url Param 'page' is: " string(key))
params := url.Values{
"page[size]": []string{"100"},
"page[" key "]": []string{"1"},
}
u := &url.URL{
Scheme: "https",
Host: "url.com",
Path: "/path",
RawQuery: params.Encode(),
}
// create http client to make GET request
client := &http.Client{}
// create a variable for the JSON model expected from Terraform Cloud API
var data models.TerraformResponse
req, err := http.NewRequest("GET", u.String(), nil)
}
CodePudding user response:
You should probably be constructing the URL and query using the net/url
package. This has the advantage that it is much safer.
params := url.Values{
"page[size]": []string{"100"},
"page[" key "]": []string{"1"},
}
u := &url.URL{
Scheme: "https",
Host: "url.com",
Path: "/path",
RawQuery: params.Encode(),
}
req, err := http.NewRequest("GET", u.String(), nil)
Trying to use fmt.Sprintf()
to construct URLs is a bit more likely to backfire.
If you want to construct a URL with fmt.Sprintf
, you’ll need to escape all the %
in the format string, and escape special characters in the arguments.
fmt.Sprint("https://url.com/path?&page%[size%]=100&page%[%s%]=1",
url.QueryEscape(key))
The url.QueryEscape()
function escapes the characters in a string so it can be safely placed in a URL query. It’s not necessary if you construct the URL with url.Values
and url.URL
.