respond: Added basic HTTP response writing utils.

internal/respond/error.go

@@ -0,0 +1,18 @@
+package respond
+
+import "net/http"
+
+// Error responds with a standardized error object.
+func Error(w http.ResponseWriter, code int, kind string, message string) {
+	type errorContent struct {
+		Code    int    `json:"code"`
+		Kind    string `json:"kind"`
+		Message string `json:"message"`
+	}
+
+	JSON(w, code, &errorContent{
+		Code:    code,
+		Kind:    kind,
+		Message: message,
+	})
+}

internal/respond/json.go

@@ -0,0 +1,14 @@
+package respond
+
+import (
+	"encoding/json"
+	"net/http"
+)
+
+// JSON gets the json value.
+func JSON(w http.ResponseWriter, code int, data interface{}) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(code)
+
+	json.NewEncoder(w).Encode(data)
+}