Fixed $elemMatch operator handling

Author: oskardudycz

src/packages/pongo/src/e2e/compatibilityTest.e2e.spec.ts

@@ -464,7 +464,7 @@ void describe('MongoDB Compatibility Tests', () => {
       );
     });
 
-    void it.skip('should find documents with a nested array element match filter in both PostgreSQL and MongoDB', async () => {
+    void it('should find documents with a nested array element match filter in both PostgreSQL and MongoDB', async () => {
       const pongoCollection = pongoDb.collection<User>('testCollection');
       const mongoCollection = mongoDb.collection<User>('testCollection');
 

src/packages/pongo/src/postgres/filter/index.ts

@@ -22,7 +22,7 @@ const constructComplexFilterQuery = (
     .map(
       ([nestedKey, val]) =>
         isEquality
-          ? handleOperator(`${key}.${nestedKey}`, '$eq', val) //regular value
+          ? handleOperator(`${key}.${nestedKey}`, '$eq', val) // regular value
           : handleOperator(key, nestedKey, val), // operator
     )
     .join(` ${AND} `);

src/packages/pongo/src/postgres/filter/queryOperators.ts

@@ -48,11 +48,18 @@ export const handleOperator = (
         `{${path.split('.').join(',')}}`,
         (value as unknown[]).map((v) => format('%L', v)).join(', '),
       );
-    case '$elemMatch':
+    case '$elemMatch': {
+      const subQuery = Object.entries(value as Record<string, unknown>)
+        .map(([subKey, subValue]) =>
+          format(`@."%s" == %s`, subKey, JSON.stringify(subValue)),
+        )
+        .join(' && ');
       return format(
-        'data @> %L::jsonb',
-        JSON.stringify(buildNestedObject(path, { $elemMatch: value })),
+        `jsonb_path_exists(data, '$.%s[*] ? (%s)')`,
+        path,
+        subQuery,
       );
+    }
     case '$all':
       return format(
         'data @> %L::jsonb',