fix(vector-stores): improve milvus wildcard search (#6187)

mem0/vector_stores/milvus.py

@@ -159,7 +159,10 @@ class MilvusDB(VectorStoreBase):
         for key, value in filters.items():
             if not self._SAFE_FILTER_KEY.match(key):
                 raise ValueError(f"Invalid filter key: {key!r}")
-            if isinstance(value, str):
+            if value == "*":
+                # Wildcard - match any value (MilvusDB doesn't have direct wildcard, so we skip this filter)
+                continue
+            elif isinstance(value, str):
                 escaped = value.replace("\\", "\\\\").replace('"', '\\"')
                 operands.append(f'(metadata["{key}"] == "{escaped}")')
             elif isinstance(value, (int, float, bool)):

tests/vector_stores/test_milvus.py

@@ -107,6 +107,14 @@ class TestMilvusDB:
         assert 'metadata["category"] == "work"' in filter_str
         assert ' and ' in filter_str
 
+    def test_create_filter_wildcard_conditions(self, milvus_db):
+        """Test filter creation with wildcard conditions."""
+        filters = {"user_id": "alice", "run_id": "*"}
+        filter_str = milvus_db._create_filter(filters)
+
+        assert 'metadata["user_id"] == "alice"' in filter_str
+        assert 'metadata["run_id"] == "*"' not in filter_str
+
     def test_search_with_filters(self, milvus_db, mock_milvus_client):
         """Test search with metadata filters (reproduces user's bug scenario)."""
         # Setup mock return value