add happ base service

lib/app/services.js

@@ -0,0 +1,52 @@
+/**
+ * BaseModelService
+ *
+ * @by Vunb
+ * @date 09/12/2016
+ *
+ */
+class BaseModelService {
+    constructor(model) {
+        // init default model
+        this.model = model;
+    }
+
+    /**
+     * get model
+     */
+    getModel() {
+        return this.model;
+    }
+
+    /**
+     * Allow search and pagination
+     */
+    bySearch(criterias, pageSize, pageIndex) {
+
+        let limit = (pageSize || 0) * 1;
+        let skip = (pageIndex || 0) * limit;
+        return this.model.find(criterias)
+            .skip(skip)
+            .limit(limit)
+            .then((results) => {
+                let count = this.model.count(criterias)
+                    .then(result => {
+                        return result;
+                    });
+                // return an Array promises
+                return [results, count];
+            })
+            .spread((results, count) => {
+                // return an object
+                return {
+                    total: count,
+                    List: results
+                };
+            });
+    }
+}
+
+// Export module
+module.exports = new BaseModelService();
+// Backwards-compat with node 0.10.x
+exports.BaseModelService = BaseModelService;