Add csv renderer

csv.go

@@ -0,0 +1,57 @@
+package middlewares
+
+import (
+	"bytes"
+	"encoding/json"
+	"sort"
+	"strconv"
+	"strings"
+)
+
+func csvFromJSON(b []byte) (result []byte, err error) {
+	var data []map[string]interface{}
+	err = json.Unmarshal(b, &data)
+	if err != nil {
+		return
+	}
+	if len(data) == 0 {
+		return
+	}
+	keys := make([]string, 0, len(data[0]))
+	for k := range data[0] {
+		keys = append(keys, k)
+	}
+	sort.Strings(keys)
+	var strOut bytes.Buffer
+	line := strings.Join(keys, ";") + "\n"
+	strOut.WriteString(line)
+	for _, v := range data {
+		values := decodeLine(keys, v)
+		line := strings.Join(values, ";") + "\n"
+		strOut.WriteString(line)
+	}
+	return strOut.Bytes(), nil
+}
+
+func decodeLine(keys []string, data map[string]interface{}) []string {
+	values := make([]string, 0, len(data))
+	for _, k := range keys {
+		v := data[k]
+		switch vv := v.(type) {
+		case map[string]interface{}:
+			values = append(values, "nil")
+		case string:
+			vv = `"` + strings.ReplaceAll(vv, `"`, " ") + `"`
+			values = append(values, vv)
+		case float64:
+			values = append(values, strconv.FormatFloat(vv, 'f', -1, 64))
+		case []interface{}:
+			values = append(values, "nil")
+		case bool:
+			values = append(values, strconv.FormatBool(vv))
+		default:
+			values = append(values, "nil")
+		}
+	}
+	return values
+}

utils.go

@@ -52,6 +52,9 @@ func renderFormat(w http.ResponseWriter, recorder *httptest.ResponseRecorder, fo
 		m := make(map[string]string)
 		m["error"] = strings.TrimSpace(string(byt))
 		byt, _ = json.MarshalIndent(m, "", "\t")
+		if format == "csv" {
+			format = "json"
+		}
 	}
 	switch format {
 	case "xml":
@@ -64,6 +67,15 @@ func renderFormat(w http.ResponseWriter, recorder *httptest.ResponseRecorder, fo
 		w.Header().Set("Content-Type", "application/xml")
 		w.WriteHeader(recorder.Code)
 		w.Write([]byte(xmlStr))
+	case "csv":
+		result, err := csvFromJSON(byt)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusBadRequest)
+			return
+		}
+		w.Header().Set("Content-Type", "text/plain")
+		w.WriteHeader(recorder.Code)
+		w.Write(result)
 	default:
 		w.Header().Set("Content-Type", "application/json")
 		w.WriteHeader(recorder.Code)