fix: Make Go SDK set correct content-type header (#1283)

This change makes Go SDK set Content-Type header according to the body's type. Either text/plain if it is a string, or application/json if it is JSON formatted string. The oauth2 transport automatically sets a url encoded content type header for login call. This change will fix requests 500'ing on % being in the json formatted body.

Fixes issue #1075

Author: jeremytchang

go/rtl/auth.go

@@ -91,14 +91,46 @@ func (s *AuthSession) Do(result interface{}, method, ver, path string, reqPars m
 	// prepare URL
 	u := fmt.Sprintf("%s/api%s%s", s.Config.BaseUrl, ver, path)
 
-	bodyString := serializeBody(body)
+	bodyString := ""
+	contentTypeHeader := ""
+
+	// serialize body to string and determine request's Content-Type header
+	if body != nil {
+		// get the `body`'s type
+		kind := reflect.TypeOf(body).Kind()
+		value := reflect.ValueOf(body)
+
+		// check if it is pointer
+		if kind == reflect.Ptr {
+			// if so find the type it points to
+			kind = reflect.ValueOf(body).Elem().Kind()
+			value = reflect.ValueOf(body).Elem()
+		}
+
+		if kind == reflect.String {
+			contentTypeHeader = "text/plain"
+			bodyString = fmt.Sprintf("%v", value)
+		} else {
+			contentTypeHeader = "application/json"
+			serializedBody, err := json.Marshal(body)
+
+			if err != nil {
+				_, _ = fmt.Fprintf(os.Stderr, "error serializing body: %v", err)
+			}
+
+			bodyString = string(serializedBody)
+		}
+	}
 
 	// create new request
 	req, err := http.NewRequest(method, u, bytes.NewBufferString(bodyString))
 	if err != nil {
 		return err
 	}
 
+	// set content-type header
+	req.Header.Add("Content-Type", contentTypeHeader)
+
 	// set query params
 	setQuery(req.URL, reqPars)
 
@@ -138,38 +170,6 @@ func (s *AuthSession) Do(result interface{}, method, ver, path string, reqPars m
 	return nil
 }
 
-// serializeBody serializes body to a json, if the body is already string, it will just return it unchanged
-func serializeBody(body interface{}) string {
-	ret := ""
-	if body == nil {
-		return ret
-	}
-
-	// get the `body` type
-	kind := reflect.TypeOf(body).Kind()
-	value := reflect.ValueOf(body)
-
-	// check if it is pointer
-	if kind == reflect.Ptr {
-		// if so, use the value kind
-		kind = reflect.ValueOf(body).Elem().Kind()
-		value = reflect.ValueOf(body).Elem()
-	}
-
-	// it is string, return it as it is
-	if kind == reflect.String {
-		return fmt.Sprintf("%v", value)
-	}
-
-	bb, err := json.Marshal(body)
-	if err != nil {
-		_, _ = fmt.Fprintf(os.Stderr, "error serializing body: %v", err)
-	}
-
-	return string(bb)
-
-}
-
 func isStringType(v interface{}) bool {
 	return reflect.ValueOf(v).Kind() == reflect.String
 }

go/rtl/auth_test.go

@@ -388,6 +388,71 @@ func TestAuthSession_Do_Parse(t *testing.T) {
 	})
 }
 
+func TestAuthSession_Do_Content_Type(t *testing.T) {
+	const path = "/someMethod"
+	const apiVersion = "/4.0"
+
+	t.Run("Do() sets Content-Type header to 'application/json' if body is json", func(t *testing.T) {
+		mux := http.NewServeMux()
+		setupApi40Login(mux, foreverValidTestToken, http.StatusOK)
+		server := httptest.NewServer(mux)
+		defer server.Close()
+
+		mux.HandleFunc("/api"+apiVersion+path, func(w http.ResponseWriter, r *http.Request) {
+			contentTypeHeader := r.Header.Get("Content-Type")
+			expectedHeader := "application/json"
+			if contentTypeHeader != expectedHeader {
+				t.Errorf("Content-Type header not correct. got=%v want=%v", contentTypeHeader, expectedHeader)
+			}
+		})
+
+		s := NewAuthSession(ApiSettings{
+			BaseUrl:    server.URL,
+			ApiVersion: apiVersion,
+		})
+
+		var r string
+		body := struct {
+			key    string
+		}{
+			key:    "value",
+		}
+
+		err := s.Do(&r, "GET", apiVersion, path, nil, body, nil)
+
+		if err != nil {
+			t.Errorf("Do() call failed: %v", err)
+		}
+	})
+
+	t.Run("Do() sets Content-Type header to 'text/plain' if body is a string", func(t *testing.T) {
+		mux := http.NewServeMux()
+		setupApi40Login(mux, foreverValidTestToken, http.StatusOK)
+		server := httptest.NewServer(mux)
+		defer server.Close()
+
+		mux.HandleFunc("/api"+apiVersion+path, func(w http.ResponseWriter, r *http.Request) {
+			contentTypeHeader := r.Header.Get("Content-Type")
+			expectedHeader := "text/plain"
+			if contentTypeHeader != expectedHeader {
+				t.Errorf("Content-Type header not correct. got=%v want=%v", contentTypeHeader, expectedHeader)
+			}
+		})
+
+		s := NewAuthSession(ApiSettings{
+			BaseUrl:    server.URL,
+			ApiVersion: apiVersion,
+		})
+
+		var r string
+		err := s.Do(&r, "GET", apiVersion, path, nil, "body", nil)
+
+		if err != nil {
+			t.Errorf("Do() call failed: %v", err)
+		}
+	})
+}
+
 func TestSetQuery(t *testing.T) {
 	somestring := "somestring"
 	testcases := []struct {