refactoring copy controller middlewares

app/controllers/copy_controller.js

@@ -34,8 +34,8 @@ CopyController.prototype.route = function (app) {
             authorizationMiddleware(this.metadataBackend),
             connectionParamsMiddleware(this.userDatabaseService),
             timeoutLimitsMiddleware(this.metadataBackend),
-            this.handleCopyFrom.bind(this),
-            this.responseCopyFrom.bind(this),
+            handleCopyFrom(),
+            responseCopyFrom(),
             errorMiddleware()
         ];
     };
@@ -106,7 +106,8 @@ function handleCopyTo (statsClient) {
     };
 }
 
-CopyController.prototype.handleCopyFrom = function (req, res, next) {
+function handleCopyFrom () {
+    return function handleCopyFromMiddleware (req, res, next) {
         const { sql } = req.query;
 
         if (!sql) {
@@ -158,10 +159,11 @@ CopyController.prototype.handleCopyFrom = function (req, res, next) {
         } catch (err) {
             next(err);
         }
+    };
+}
 
-};
-
-CopyController.prototype.responseCopyFrom = function (req, res, next) {
+function responseCopyFrom () {
+    return function responseCopyFromMiddleware (req, res, next) {
         if (!res.body || !res.body.total_rows) {
             return next(new Error("No rows copied"));
         }
@@ -180,6 +182,7 @@ CopyController.prototype.responseCopyFrom = function (req, res, next) {
         }
 
         res.send(res.body);
-};
+    };
+}
 
 module.exports = CopyController;