utils: persist empty paths as the req location itself

Fixes express-validator#598

utils/persist-values.js

@@ -5,6 +5,8 @@ module.exports = (req, fieldInstances) => {
     const initialValue = _.get(req[instance.location], instance.path);
     return initialValue !== instance.value;
   }).forEach(instance => {
-    _.set(req[instance.location], instance.path, instance.value);
+    instance.path === ''
+      ? _.set(req, instance.location, instance.value)
+      : _.set(req[instance.location], instance.path, instance.value);
   });
 };

utils/persist-values.spec.js

@@ -17,6 +17,13 @@ describe('utils: persistValues', () => {
     expect(req.body.bar.baz).to.equal('qux');
   });
 
+  it('persists empty paths as the req location itself', () => {
+    const req = {};
+    persistValues(req, [{ location: 'body', path: '', value: 'noice' }]);
+
+    expect(req.body).to.equal('noice');
+  });
+
   it('does not persist undefined values into req when the key does not exist', () => {
     const req = {
       query: {}