diff --git a/lightrag/kg/mongo_impl.py b/lightrag/kg/mongo_impl.py
index a6a33084..339693ee 100644
--- a/lightrag/kg/mongo_impl.py
+++ b/lightrag/kg/mongo_impl.py
@@ -83,8 +83,8 @@ class ClientManager:
 @final
 @dataclass
 class MongoKVStorage(BaseKVStorage):
-    db: AsyncIOMotorDatabase = field(init=False)
-    _data: AsyncIOMotorCollection = field(init=False)
+    db: AsyncIOMotorDatabase = field(default=None)
+    _data: AsyncIOMotorCollection = field(default=None)
 
     def __post_init__(self):
         self._collection_name = self.namespace
@@ -156,8 +156,8 @@ class MongoKVStorage(BaseKVStorage):
 @final
 @dataclass
 class MongoDocStatusStorage(DocStatusStorage):
-    db: AsyncIOMotorDatabase = field(init=False)
-    _data: AsyncIOMotorCollection = field(init=False)
+    db: AsyncIOMotorDatabase = field(default=None)
+    _data: AsyncIOMotorCollection = field(default=None)
 
     def __post_init__(self):
         self._collection_name = self.namespace
@@ -236,8 +236,8 @@ class MongoGraphStorage(BaseGraphStorage):
     A concrete implementation using MongoDB's $graphLookup to demonstrate multi-hop queries.
     """
 
-    db: AsyncIOMotorDatabase = field(init=False)
-    collection: AsyncIOMotorCollection = field(init=False)
+    db: AsyncIOMotorDatabase = field(default=None)
+    collection: AsyncIOMotorCollection = field(default=None)
 
     def __init__(self, namespace, global_config, embedding_func):
         super().__init__(
@@ -798,8 +798,8 @@ class MongoGraphStorage(BaseGraphStorage):
 @final
 @dataclass
 class MongoVectorDBStorage(BaseVectorStorage):
-    db: AsyncIOMotorDatabase = field(init=False)
-    _data: AsyncIOMotorCollection = field(init=False)
+    db: AsyncIOMotorDatabase = field(default=None)
+    _data: AsyncIOMotorCollection = field(default=None)
 
     def __post_init__(self):
         kwargs = self.global_config.get("vector_db_storage_cls_kwargs", {})
diff --git a/lightrag/kg/oracle_impl.py b/lightrag/kg/oracle_impl.py
index 70c5258c..e19d5125 100644
--- a/lightrag/kg/oracle_impl.py
+++ b/lightrag/kg/oracle_impl.py
@@ -242,7 +242,7 @@ class ClientManager:
 @final
 @dataclass
 class OracleKVStorage(BaseKVStorage):
-    db: OracleDB = field(init=False)
+    db: OracleDB = field(default=None)
     meta_fields = None
 
     def __post_init__(self):
@@ -394,7 +394,7 @@ class OracleKVStorage(BaseKVStorage):
 @final
 @dataclass
 class OracleVectorDBStorage(BaseVectorStorage):
-    db: OracleDB = field(init=False)
+    db: OracleDB = field(default=None)
 
     def __post_init__(self):
         config = self.global_config.get("vector_db_storage_cls_kwargs", {})
@@ -450,7 +450,7 @@ class OracleVectorDBStorage(BaseVectorStorage):
 @final
 @dataclass
 class OracleGraphStorage(BaseGraphStorage):
-    db: OracleDB = field(init=False)
+    db: OracleDB = field(default=None)
 
     def __post_init__(self):
         self._max_batch_size = self.global_config.get("embedding_batch_num", 10)
diff --git a/lightrag/kg/postgres_impl.py b/lightrag/kg/postgres_impl.py
index 654dc6dd..6977e0a6 100644
--- a/lightrag/kg/postgres_impl.py
+++ b/lightrag/kg/postgres_impl.py
@@ -246,7 +246,7 @@ class ClientManager:
 @final
 @dataclass
 class PGKVStorage(BaseKVStorage):
-    db: PostgreSQLDB = field(init=False)
+    db: PostgreSQLDB = field(default=None)
 
     def __post_init__(self):
         self._max_batch_size = self.global_config["embedding_batch_num"]
@@ -378,7 +378,7 @@ class PGKVStorage(BaseKVStorage):
 @final
 @dataclass
 class PGVectorStorage(BaseVectorStorage):
-    db: PostgreSQLDB = field(init=False)
+    db: PostgreSQLDB = field(default=None)
 
     def __post_init__(self):
         self._max_batch_size = self.global_config["embedding_batch_num"]
@@ -515,7 +515,7 @@ class PGVectorStorage(BaseVectorStorage):
 @final
 @dataclass
 class PGDocStatusStorage(DocStatusStorage):
-    db: PostgreSQLDB = field(init=False)
+    db: PostgreSQLDB = field(default=None)
 
     async def initialize(self):
         if self.db is None:
@@ -665,7 +665,7 @@ class PGGraphQueryException(Exception):
 @final
 @dataclass
 class PGGraphStorage(BaseGraphStorage):
-    db: PostgreSQLDB = field(init=False)
+    db: PostgreSQLDB = field(default=None)
 
     @staticmethod
     def load_nx_graph(file_name):
diff --git a/lightrag/kg/tidb_impl.py b/lightrag/kg/tidb_impl.py
index e5c6995e..2545d580 100644
--- a/lightrag/kg/tidb_impl.py
+++ b/lightrag/kg/tidb_impl.py
@@ -166,7 +166,7 @@ class ClientManager:
 @final
 @dataclass
 class TiDBKVStorage(BaseKVStorage):
-    db: TiDB = field(init=False)
+    db: TiDB = field(default=None)
 
     def __post_init__(self):
         self._data = {}
@@ -279,7 +279,7 @@ class TiDBKVStorage(BaseKVStorage):
 @final
 @dataclass
 class TiDBVectorDBStorage(BaseVectorStorage):
-    db: TiDB = field(init=False)
+    db: TiDB = field(default=None)
 
     def __post_init__(self):
         self._client_file_name = os.path.join(
@@ -422,7 +422,7 @@ class TiDBVectorDBStorage(BaseVectorStorage):
 @final
 @dataclass
 class TiDBGraphStorage(BaseGraphStorage):
-    db: TiDB = field(init=False)
+    db: TiDB = field(default=None)
 
     def __post_init__(self):
         self._max_batch_size = self.global_config["embedding_batch_num"]