Merge pull request Automattic#14749 from 0x0a0d/improve_fix_cast_empty_query

Improve fix cast empty query

Author: vkarpov15

lib/cast.js

@@ -69,7 +69,17 @@ module.exports = function cast(schema, obj, options, context) {
         if (val[k] == null || typeof val[k] !== 'object') {
           throw new CastError('Object', val[k], path + '.' + k);
         }
+
+        const beforeCastKeysLength = Object.keys(val[k]).length;
         val[k] = cast(schema, val[k], options, context);
+        if (Object.keys(val[k]).length === 0 && beforeCastKeysLength !== 0) {
+          val.splice(k, 1);
+        }
+      }
+
+      // delete empty: {$or: []} -> {}
+      if (val.length === 0) {
+        delete obj[path];
       }
     } else if (path === '$where') {
       type = typeof val;

test/docs/cast.test.js

@@ -136,6 +136,26 @@ describe('Cast Tutorial', function() {
       'strictQuery is \'throw\'.');
     // acquit:ignore:end
   });
+  
+  it('strictQuery removes casted empty objects', async function() {
+    mongoose.deleteModel('Character');
+    const schema = new mongoose.Schema({ name: String, age: Number }, {
+      strictQuery: true
+    });
+    Character = mongoose.model('Character', schema);
+
+    const query = Character.findOne({
+      $or: [{ notInSchema: { $lt: 'not a number' } }],
+      $and: [{ name: 'abc' }, { age: { $gt: 18 } }, { notInSchema: { $lt: 'not a number' } }],
+      $nor: [{}] // should be kept
+    });
+
+    await query.exec();
+    query.getFilter(); // Empty object `{}`, Mongoose removes `notInSchema`
+    // acquit:ignore:start
+    assert.deepEqual(query.getFilter(), { $and: [{ name: 'abc' }, { age: { $gt: 18 } }], $nor: [{}] });
+    // acquit:ignore:end
+  });
 
   it('implicit in', async function() {
     // Normally wouldn't find anything because `name` is a string, but