some progress

node_modules/mongoose/lib/plugins/validateBeforeSave.js

@@ -0,0 +1,51 @@
+'use strict';
+
+/*!
+ * ignore
+ */
+
+module.exports = function validateBeforeSave(schema) {
+  const unshift = true;
+  schema.pre('save', false, function validateBeforeSave(next, options) {
+    const _this = this;
+    // Nested docs have their own presave
+    if (this.$isSubdocument) {
+      return next();
+    }
+
+    const hasValidateBeforeSaveOption = options &&
+        (typeof options === 'object') &&
+        ('validateBeforeSave' in options);
+
+    let shouldValidate;
+    if (hasValidateBeforeSaveOption) {
+      shouldValidate = !!options.validateBeforeSave;
+    } else {
+      shouldValidate = this.$__schema.options.validateBeforeSave;
+    }
+
+    // Validate
+    if (shouldValidate) {
+      const hasValidateModifiedOnlyOption = options &&
+          (typeof options === 'object') &&
+          ('validateModifiedOnly' in options);
+      const validateOptions = hasValidateModifiedOnlyOption ?
+        { validateModifiedOnly: options.validateModifiedOnly } :
+        null;
+      this.$validate(validateOptions).then(
+        () => {
+          this.$op = 'save';
+          next();
+        },
+        error => {
+          _this.$__schema.s.hooks.execPost('save:error', _this, [_this], { error: error }, function(error) {
+            _this.$op = 'save';
+            next(error);
+          });
+        }
+      );
+    } else {
+      next();
+    }
+  }, null, unshift);
+};