feat: Add support for partialFilterExpression in MongoDB storage adapter

spec/MongoStorageAdapter.spec.js

@@ -502,6 +502,30 @@ describe_only_db('mongo')('MongoStorageAdapter', () => {
     expect(schemaAfterDeletion.fields.test).toBeUndefined();
   });
 
+  it('should create index with partialFilterExpression', async () => {
+    const database = Config.get(Parse.applicationId).database;
+    const adapter = database.adapter;
+
+    const user = new Parse.User();
+    user.set('username', 'testuser');
+    user.set('password', 'testpass');
+    await user.signUp();
+
+    const schema = await new Parse.Schema('_User').get();
+    const partialFilterExpression = { _email_verify_token: { $exists: true } };
+
+    await adapter.ensureIndex('_User', schema, ['username'], 'partial_username_index', false, {
+      partialFilterExpression,
+      sparse: false,
+    });
+
+    const indexes = await adapter.getIndexes('_User');
+    const createdIndex = indexes.find(idx => idx.name === 'partial_username_index');
+    expect(createdIndex).toBeDefined();
+    expect(createdIndex.partialFilterExpression).toEqual({ _email_verify_token: { $exists: true } });
+    expect(createdIndex.sparse).toBeFalsy();
+  });
+
   if (process.env.MONGODB_TOPOLOGY === 'replicaset') {
     describe('transactions', () => {
       const headers = {

src/Adapters/Storage/Mongo/MongoStorageAdapter.js

@@ -800,12 +800,17 @@ export class MongoStorageAdapter implements StorageAdapter {
     const caseInsensitiveOptions: Object = caseInsensitive
       ? { collation: MongoCollection.caseInsensitiveCollation() }
       : {};
+    const partialFilterOptions: Object =
+      options.partialFilterExpression !== undefined
+        ? { partialFilterExpression: options.partialFilterExpression }
+        : {};
     const indexOptions: Object = {
       ...defaultOptions,
       ...caseInsensitiveOptions,
       ...indexNameOptions,
       ...ttlOptions,
       ...sparseOptions,
+      ...partialFilterOptions,
     };
 
     return this._adaptiveCollection(className)