some progress

node_modules/mongoose/lib/helpers/projection/isInclusive.js

@@ -0,0 +1,38 @@
+'use strict';
+
+const isDefiningProjection = require('./isDefiningProjection');
+
+/*!
+ * ignore
+ */
+
+module.exports = function isInclusive(projection) {
+  if (projection == null) {
+    return false;
+  }
+
+  const props = Object.keys(projection);
+  const numProps = props.length;
+  if (numProps === 0) {
+    return false;
+  }
+
+  for (let i = 0; i < numProps; ++i) {
+    const prop = props[i];
+    // Plus paths can't define the projection (see gh-7050)
+    if (prop.startsWith('+')) {
+      continue;
+    }
+    // If field is truthy (1, true, etc.) and not an object, then this
+    // projection must be inclusive. If object, assume its $meta, $slice, etc.
+    if (isDefiningProjection(projection[prop]) && !!projection[prop]) {
+      if (projection[prop] != null && typeof projection[prop] === 'object') {
+        return isInclusive(projection[prop]);
+      } else {
+        return !!projection[prop];
+      }
+    }
+  }
+
+  return false;
+};