Unable to send JSON as body for HTTP POST request in GO

Question

When i make the POST request using the below GO Function. I get a invalid json on the server side.

If i send static json for example

var jsonprep = []byte(`{"username":"[email protected]","password":"xyz123"}`)

it does work instead of

var jsonprep string = "`{username:"+username+",password:"+password+"}`"

.

func makeHttpPostReq(url string, username string, password string){ client := http.Client{} var jsonprep string = "`{username:"+username+",password:"+password+"}`" var jsonStr = []byte(jsonprep) req, err := http.NewRequest("POST", url, bytes.NewBuffer(jsonStr)) req.Header.Set("Content-Type", "application/json") resp, err := client.Do(req) if err != nil { fmt.Println("Unable to reach the server.") } else { body, _ := ioutil.ReadAll(resp.Body) fmt.Println("body=", string(body)) } }

In addition to the answers, you can avoid all of the "fragility" around quoting if you marshal your data into JSON from a struct. See here for a minimal example: play.golang.org/p/8lGwkQPYxb - you can modify your makeHttpPostReq function to accept a User instead of two strings. — elithrar
– elithrar, Commented Jun 15, 2015 at 3:31

Rob Napier · Accepted Answer · 2015-06-15 02:54:17Z

You've got your quoting wrong:

http://play.golang.org/p/PueWyQ1atq

var jsonprep string = "`{username:"+username+",password:"+password+"}`" ===> `{username:Bob,password:pass}`

You meant:

http://play.golang.org/p/LMuwxArf8G

var jsonprep string = `{"username":"`+username+`","password":"`+password+`"}` ===> {"username":"Bob","password":"pass"}

jfly · Accepted Answer · 2015-06-15 03:24:45Z

If you use

var jsonprep string = "`{username:"+username+",password:"+password+"}`"

the server will get the data like this:

`{username:your_username,password:yourpassword}`

because the string in back quotes `` which is in the double quotes is not raw string literals, of course it's invalid json. you can compose the json string manually:

var jsonprep string = "{\"username\":\"" + username + "\",\"password\":\"" + password + "\"}"

In Go you can avoid all the confusing backslash quoting (\") by using ` (backtick) instead of " (double-quote) for the string.

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