fix: add default value for data_sources in KnowledgeBase pydantic model (#686)

Author: Mini256

backend/app/models/knowledge_base.py

@@ -118,6 +118,8 @@ class AdvancedChunkingConfig(BaseChunkingConfig):
 
 
 class KnowledgeBase(SQLModel, table=True):
+    __tablename__ = "knowledge_bases"
+
     id: Optional[int] = Field(default=None, primary_key=True)
     name: str = Field(max_length=255, nullable=False)
     description: Optional[str] = Field(sa_column=Column(MEDIUMTEXT), default=None)
@@ -173,7 +175,9 @@ class KnowledgeBase(SQLModel, table=True):
     deleted_by: UUID = Field(foreign_key="users.id", nullable=True)
     deleted_at: Optional[datetime] = Field(default=None, sa_column=Column(DateTime()))
 
-    __tablename__ = "knowledge_bases"
+    def __init__(self, **kwargs):
+        kwargs.setdefault("data_sources", [])
+        super().__init__(**kwargs)
 
     def __hash__(self):
         return hash(self.id)