add server to monorepo.

packages/server/src/models/DateSession.ts

@@ -0,0 +1,34 @@
+import moment from 'moment';
+
+export default (Model) => {
+  return class DateSession extends Model {
+
+    get timestamps() {
+      return ['createdAt', 'updatedAt'];
+    }
+
+    $beforeUpdate(opt, context) {
+      const maybePromise = super.$beforeUpdate(opt, context);
+
+      return Promise.resolve(maybePromise).then(() => {
+        const key = this.timestamps[1];
+
+        if (key && !this[key]) {
+          this[key] = moment().format('YYYY/MM/DD HH:mm:ss');
+        }
+      });
+    }
+
+    $beforeInsert(context) {
+      const maybePromise = super.$beforeInsert(context);
+
+      return Promise.resolve(maybePromise).then(() => {
+        const key = this.timestamps[0];
+
+        if (key && !this[key]) {
+          this[key] = moment().format('YYYY/MM/DD HH:mm:ss');
+        }
+      });
+    }
+  }
+}