flow like the river

BACK_BACK/node_modules/mongoose/lib/helpers/populate/validateRef.js

@@ -0,0 +1,19 @@
+'use strict';
+
+const MongooseError = require('../../error/mongooseError');
+const util = require('util');
+
+module.exports = validateRef;
+
+function validateRef(ref, path) {
+  if (typeof ref === 'string') {
+    return;
+  }
+
+  if (typeof ref === 'function') {
+    return;
+  }
+
+  throw new MongooseError('Invalid ref at path "' + path + '". Got ' +
+    util.inspect(ref, { depth: 0 }));
+}