From 2f101d0b201e215014a034d53cfd61a085c53d10 Mon Sep 17 00:00:00 2001
From: Valeri Karpov <val@karpov.io>
Date: Mon, 21 Aug 2023 09:58:59 -0400
Subject: [PATCH] fix(query+populate): add `refPath` to projection by default,
 unless explicitly excluded

Fix mongodb-js/mongoose-autopopulate#96
---
 lib/helpers/query/selectPopulatedFields.js    | 13 +++++++
 .../query.selectPopulatedFields.test.js       | 36 +++++++++++++++++++
 2 files changed, 49 insertions(+)
 create mode 100644 test/helpers/query.selectPopulatedFields.test.js

diff --git a/lib/helpers/query/selectPopulatedFields.js b/lib/helpers/query/selectPopulatedFields.js
index 92f1d87e04b..dc96caf6fa4 100644
--- a/lib/helpers/query/selectPopulatedFields.js
+++ b/lib/helpers/query/selectPopulatedFields.js
@@ -21,12 +21,25 @@ module.exports = function selectPopulatedFields(fields, userProvidedFields, popu
       } else if (userProvidedFields[path] === 0) {
         delete fields[path];
       }
+
+      const refPath = populateOptions[path]?.refPath;
+      if (typeof refPath === 'string') {
+        if (!isPathInFields(userProvidedFields, refPath)) {
+          fields[refPath] = 1;
+        } else if (userProvidedFields[refPath] === 0) {
+          delete fields[refPath];
+        }
+      }
     }
   } else if (isExclusive(fields)) {
     for (const path of paths) {
       if (userProvidedFields[path] == null) {
         delete fields[path];
       }
+      const refPath = populateOptions[path]?.refPath;
+      if (typeof refPath === 'string' && userProvidedFields[refPath] == null) {
+        delete fields[refPath];
+      }
     }
   }
 };
diff --git a/test/helpers/query.selectPopulatedFields.test.js b/test/helpers/query.selectPopulatedFields.test.js
new file mode 100644
index 00000000000..4a5924b8c64
--- /dev/null
+++ b/test/helpers/query.selectPopulatedFields.test.js
@@ -0,0 +1,36 @@
+'use strict';
+
+const assert = require('assert');
+const selectPopulatedFields = require('../../lib/helpers/query/selectPopulatedFields');
+
+describe('selectPopulatedFields', function() {
+  it('selects refPath', function() {
+    const fields = { name: 1 };
+    const userProvidedFields = { name: 1 };
+    const populateOptions = {
+      parent: {
+        refPath: 'parentModel'
+      }
+    };
+    selectPopulatedFields(fields, userProvidedFields, populateOptions);
+    assert.deepStrictEqual(fields, {
+      name: 1,
+      parent: 1,
+      parentModel: 1
+    });
+  });
+
+  it('adds refPath to projection if not deselected by user in exclusive projection', function() {
+    const fields = { name: 0, parentModel: 0 };
+    const userProvidedFields = { name: 0 };
+    const populateOptions = {
+      parent: {
+        refPath: 'parentModel'
+      }
+    };
+    selectPopulatedFields(fields, userProvidedFields, populateOptions);
+    assert.deepStrictEqual(fields, {
+      name: 0
+    });
+  });
+});