fix(document): avoid treating nested projection as inclusive when applying defaults

Fix #14115

Author: vkarpov15

lib/helpers/document/applyDefaults.js

@@ -1,5 +1,7 @@
 'use strict';
 
+const isNestedProjection = require('../projection/isNestedProjection');
+
 module.exports = function applyDefaults(doc, fields, exclude, hasIncludedChildren, isBeforeSetters, pathsToSkip) {
   const paths = Object.keys(doc.$__schema.paths);
   const plen = paths.length;
@@ -32,7 +34,7 @@ module.exports = function applyDefaults(doc, fields, exclude, hasIncludedChildre
         }
       } else if (exclude === false && fields && !included) {
         const hasSubpaths = type.$isSingleNested || type.$isMongooseDocumentArray;
-        if (curPath in fields || (j === len - 1 && hasSubpaths && hasIncludedChildren != null && hasIncludedChildren[curPath])) {
+        if ((curPath in fields && !isNestedProjection(fields[curPath])) || (j === len - 1 && hasSubpaths && hasIncludedChildren != null && hasIncludedChildren[curPath])) {
           included = true;
         } else if (hasIncludedChildren != null && !hasIncludedChildren[curPath]) {
           break;

lib/helpers/projection/hasIncludedChildren.js

@@ -21,6 +21,7 @@ module.exports = function hasIncludedChildren(fields) {
   const keys = Object.keys(fields);
 
   for (const key of keys) {
+
     if (key.indexOf('.') === -1) {
       hasIncludedChildren[key] = 1;
       continue;

lib/helpers/projection/isNestedProjection.js

@@ -0,0 +1,8 @@
+'use strict';
+
+module.exports = function isNestedProjection(val) {
+  if (val == null || typeof val !== 'object') {
+    return false;
+  }
+  return val.$slice == null && val.$elemMatch == null && val.$meta == null && val.$ == null;
+};