0.4.4 - Bug fix and add retry (#21)

* Fix bugs

* Add retry mechanism

---------

Co-authored-by: Peng Ren

Author: passren

README.md

@@ -49,6 +49,9 @@ PyMongoSQL implements the DB API 2.0 interfaces to provide SQL-like access to Mo
 - **JMESPath** (JSON/Dict Path Query)
   - jmespath >= 1.0.0
 
+- **Tenacity** (Transient Failure Retry)
+    - tenacity >= 9.0.0
+
 ### Optional Dependencies
 
 - **SQLAlchemy** (for ORM/Core support)
@@ -206,6 +209,22 @@ cursor.execute(
 
 Parameters are substituted into the MongoDB filter during execution, providing protection against injection attacks.
 
+### Retry on Transient System Errors
+
+PyMongoSQL supports retrying transient, system-level MongoDB failures (for example connection timeout and reconnect errors) using Tenacity.
+
+```python
+connection = connect(
+    host="mongodb://localhost:27017/database",
+    retry_enabled=True,     # default: True
+    retry_attempts=3,       # default: 3
+    retry_wait_min=0.1,     # default: 0.1 seconds
+    retry_wait_max=1.0,     # default: 1.0 seconds
+)
+```
+
+These options apply to connection ping checks, query/DML command execution, and paginated `getMore` fetches.
+
 ## Supported SQL Features
 
 ### SELECT Statements

pymongosql/__init__.py

@@ -6,7 +6,7 @@
 if TYPE_CHECKING:
     from .connection import Connection
 
-__version__: str = "0.4.3"
+__version__: str = "0.4.4"
 
 # Globals https://www.python.org/dev/peps/pep-0249/#globals
 apilevel: str = "2.0"
@@ -36,6 +36,115 @@ def __hash__(self):
         return frozenset.__hash__(self)
 
 
+# DB API 2.0 Type Objects for MongoDB Data Types
+# https://www.python.org/dev/peps/pep-0249/#type-objects-and-constructors
+# Mapping of MongoDB BSON types to DB API 2.0 type objects
+
+# Null/None type
+NULL = DBAPITypeObject(("null", "Null", "NULL"))
+
+# String types
+STRING = DBAPITypeObject(("string", "str", "String", "VARCHAR", "CHAR", "TEXT"))
+
+# Numeric types - Integer
+BINARY = DBAPITypeObject(("binary", "Binary", "BINARY", "VARBINARY", "BLOB", "ObjectId"))
+
+# Numeric types - Integer
+NUMBER = DBAPITypeObject(("int", "integer", "long", "int32", "int64", "Integer", "BIGINT", "INT"))
+
+# Numeric types - Decimal/Float
+FLOAT = DBAPITypeObject(("double", "decimal", "float", "Double", "DECIMAL", "FLOAT", "NUMERIC"))
+
+# Boolean type
+BOOLEAN = DBAPITypeObject(("bool", "boolean", "Bool", "BOOLEAN"))
+
+# Date/Time types
+DATE = DBAPITypeObject(("date", "Date", "DATE"))
+TIME = DBAPITypeObject(("time", "Time", "TIME"))
+DATETIME = DBAPITypeObject(("datetime", "timestamp", "Timestamp", "DATETIME", "TIMESTAMP"))
+
+# Aggregate types
+ARRAY = DBAPITypeObject(("array", "Array", "ARRAY", "list"))
+OBJECT = DBAPITypeObject(("object", "Object", "OBJECT", "struct", "dict", "document"))
+
+# Special MongoDB types
+OBJECTID = DBAPITypeObject(("objectid", "ObjectId", "OBJECTID", "oid"))
+REGEX = DBAPITypeObject(("regex", "Regex", "REGEX", "regexp"))
+
+# Map MongoDB BSON type codes to DB API type objects
+# This mapping helps cursor.description identify the correct type for each column
+_MONGODB_TYPE_MAP = {
+    "null": NULL,
+    "string": STRING,
+    "int": NUMBER,
+    "integer": NUMBER,
+    "long": NUMBER,
+    "int32": NUMBER,
+    "int64": NUMBER,
+    "double": FLOAT,
+    "decimal": FLOAT,
+    "float": FLOAT,
+    "bool": BOOLEAN,
+    "boolean": BOOLEAN,
+    "date": DATE,
+    "datetime": DATETIME,
+    "timestamp": DATETIME,
+    "array": ARRAY,
+    "object": OBJECT,
+    "document": OBJECT,
+    "bson.objectid": OBJECTID,
+    "objectid": OBJECTID,
+    "regex": REGEX,
+    "binary": BINARY,
+}
+
+
+def get_type_code(value: object) -> str:
+    """Get the type code for a MongoDB value.
+
+    Maps a MongoDB/Python value to its corresponding DB API type code string.
+
+    Args:
+        value: The value to determine the type for
+
+    Returns:
+        A string representing the DB API type code
+    """
+    if value is None:
+        return "null"
+    elif isinstance(value, bool):
+        return "bool"
+    elif isinstance(value, int):
+        return "int"
+    elif isinstance(value, float):
+        return "double"
+    elif isinstance(value, str):
+        return "string"
+    elif isinstance(value, bytes):
+        return "binary"
+    elif isinstance(value, dict):
+        return "object"
+    elif isinstance(value, list):
+        return "array"
+    elif hasattr(value, "__class__") and value.__class__.__name__ == "ObjectId":
+        return "objectid"
+    else:
+        return "object"
+
+
+def get_type_object(value: object) -> DBAPITypeObject:
+    """Get the DB API type object for a MongoDB value.
+
+    Args:
+        value: The value to get type information for
+
+    Returns:
+        A DBAPITypeObject representing the value's type
+    """
+    type_code = get_type_code(value)
+    return _MONGODB_TYPE_MAP.get(type_code, OBJECT)
+
+
 def connect(*args, **kwargs) -> "Connection":
     from .connection import Connection
 

pymongosql/connection.py

@@ -13,6 +13,7 @@
 from .cursor import Cursor
 from .error import DatabaseError, OperationalError
 from .helper import ConnectionHelper
+from .retry import RetryConfig, execute_with_retry
 
 _logger = logging.getLogger(__name__)
 
@@ -55,6 +56,10 @@ def __init__(
         if not self._mode and mode:
             self._mode = mode
 
+        # Retry behavior for transient system-level PyMongo failures.
+        # These kwargs are consumed by PyMongoSQL and are not passed to MongoClient.
+        self._retry_config = RetryConfig.from_kwargs(kwargs)
+
         # Extract commonly used parameters for backward compatibility
         self._host = host or "localhost"
         self._port = port or 27017
@@ -109,7 +114,11 @@ def _connect(self) -> None:
             self._client = MongoClient(**self._pymongo_params)
 
             # Test connection
-            self._client.admin.command("ping")
+            execute_with_retry(
+                lambda: self._client.admin.command("ping"),
+                self._retry_config,
+                "initial MongoDB ping",
+            )
 
             # Initialize the database according to explicit parameter or client's default
             # This may raise OperationalError if no database could be determined; allow it to bubble up
@@ -179,6 +188,11 @@ def mode(self) -> str:
         """Get the specified mode"""
         return self._mode
 
+    @property
+    def retry_config(self) -> RetryConfig:
+        """Get retry configuration used for transient system-level errors."""
+        return self._retry_config
+
     def use_database(self, database_name: str) -> None:
         """Switch to a different database"""
         if self._client is None:
@@ -332,15 +346,23 @@ def _start_session(self, **kwargs) -> ClientSession:
         if self._client is None:
             raise OperationalError("No active connection")
 
-        session = self._client.start_session(**kwargs)
+        session = execute_with_retry(
+            lambda: self._client.start_session(**kwargs),
+            self._retry_config,
+            "start MongoDB session",
+        )
         self._session = session
         _logger.info("Started new MongoDB session")
         return session
 
     def _end_session(self) -> None:
         """End the current session (internal method)"""
         if self._session is not None:
-            self._session.end_session()
+            execute_with_retry(
+                lambda: self._session.end_session(),
+                self._retry_config,
+                "end MongoDB session",
+            )
             self._session = None
             _logger.info("Ended MongoDB session")
 
@@ -357,7 +379,11 @@ def _start_transaction(self, **kwargs) -> None:
         if self._session is None:
             raise OperationalError("No active session")
 
-        self._session.start_transaction(**kwargs)
+        execute_with_retry(
+            lambda: self._session.start_transaction(**kwargs),
+            self._retry_config,
+            "start MongoDB transaction",
+        )
         self._in_transaction = True
         self._autocommit = False
         _logger.info("Started MongoDB transaction")
@@ -370,7 +396,11 @@ def _commit_transaction(self) -> None:
         if not self._session.in_transaction:
             raise OperationalError("No active transaction to commit")
 
-        self._session.commit_transaction()
+        execute_with_retry(
+            lambda: self._session.commit_transaction(),
+            self._retry_config,
+            "commit MongoDB transaction",
+        )
         self._in_transaction = False
         self._autocommit = True
         _logger.info("Committed MongoDB transaction")
@@ -383,7 +413,11 @@ def _abort_transaction(self) -> None:
         if not self._session.in_transaction:
             raise OperationalError("No active transaction to abort")
 
-        self._session.abort_transaction()
+        execute_with_retry(
+            lambda: self._session.abort_transaction(),
+            self._retry_config,
+            "abort MongoDB transaction",
+        )
         self._in_transaction = False
         self._autocommit = True
         _logger.info("Aborted MongoDB transaction")
@@ -460,7 +494,11 @@ def test_connection(self) -> bool:
         """Test if the connection is alive"""
         try:
             if self._client:
-                self._client.admin.command("ping")
+                execute_with_retry(
+                    lambda: self._client.admin.command("ping"),
+                    self._retry_config,
+                    "connection health check ping",
+                )
                 return True
             return False
         except Exception as e:

pymongosql/cursor.py

@@ -110,6 +110,7 @@ def execute(self: _T, operation: str, parameters: Optional[Any] = None) -> _T:
                     command_result=result,
                     execution_plan=execution_plan_for_rs,
                     database=self.connection.database,
+                    retry_config=self.connection.retry_config,
                     **self._kwargs,
                 )
             else:
@@ -125,6 +126,7 @@ def execute(self: _T, operation: str, parameters: Optional[Any] = None) -> _T:
                     },
                     execution_plan=stub_plan,
                     database=self.connection.database,
+                    retry_config=self.connection.retry_config,
                     **self._kwargs,
                 )
                 # Store the actual insert result for reference