Merge pull request #12797 from lpizzinidev/gh-12794

fix(query): update queries removes fields set to `undefined`
Automattic · Dec 16, 2022 · ff67167 · ff67167
2 parents 0ed6e71 + 99b6cca
commit ff67167
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diff --git a/lib/helpers/query/castUpdate.js b/lib/helpers/query/castUpdate.js
@@ -84,6 +84,12 @@ module.exports = function castUpdate(schema, obj, options, context, filter) {
     const op = ops[i];
     val = ret[op];
     hasDollarKey = hasDollarKey || op.startsWith('$');
+    const toUnset = {};
+    for (const key of Object.keys(val)) {
+      if (val[key] === undefined) {
+        toUnset[key] = 1;
+      }
+    }
 
     if (val &&
         typeof val === 'object' &&
@@ -100,6 +106,10 @@ module.exports = function castUpdate(schema, obj, options, context, filter) {
 
     if (op.startsWith('$') && utils.isEmptyObject(val)) {
       delete ret[op];
+      if (op === '$set' && !utils.isEmptyObject(toUnset)) {
+        // Unset all undefined values
+        ret['$unset'] = toUnset;
+      }
     }
   }
 

diff --git a/test/query.test.js b/test/query.test.js
@@ -4313,4 +4313,30 @@ describe('Query', function() {
     assert.strictEqual(found.length, 1);
     assert.strictEqual(found[0].title, 'burrito bowl');
   });
+
+  it('update operation should remove fields set to undefined (gh-12794)', async() => {
+    const m = new mongoose.Mongoose();
+
+    await m.connect(start.uri);
+
+    const schema = new mongoose.Schema({ title: String });
+
+    const Test = m.model('test', schema);
+
+    const doc = await Test.create({
+      title: 'test'
+    });
+
+    assert.strictEqual(doc.title, 'test');
+
+    const updatedDoc = await Test.findOneAndUpdate(
+      {
+        _id: doc._id
+      },
+      { title: undefined },
+      { returnOriginal: false }
+    ).lean();
+
+    assert.ok('title' in updatedDoc === false);
+  });
 });