Fix nullable attribute for created_at and updated_at fields in Variable model (#1669)

* Fix nullable attribute for created_at field in variable table

* Update package versions in pyproject.toml and poetry.lock files

* Fix nullable attribute for created_at and updated_at fields in Variable model

* Refactor VariableService class to use VariableCreate model for creating variables

src/backend/base/langflow/alembic/versions/e3bc869fa272_fix_nullable.py

@@ -0,0 +1,60 @@
+"""Fix nullable
+
+Revision ID: e3bc869fa272
+Revises: 1a110b568907
+Create Date: 2024-04-10 19:17:22.820455
+
+"""
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+from sqlalchemy.dialects import postgresql
+from sqlalchemy.engine.reflection import Inspector
+
+# revision identifiers, used by Alembic.
+revision: str = "e3bc869fa272"
+down_revision: Union[str, None] = "1a110b568907"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    conn = op.get_bind()
+    inspector = Inspector.from_engine(conn)  # type: ignore
+    table_names = inspector.get_table_names()
+    # ### commands auto generated by Alembic - please adjust! ###
+    if "variable" not in table_names:
+        return
+
+    column_names = [column["name"] for column in inspector.get_columns("variable")]
+
+    with op.batch_alter_table("variable", schema=None) as batch_op:
+        if "created_at" in column_names:
+            batch_op.alter_column(
+                "created_at",
+                existing_type=sa.TIMESTAMP(timezone=True),
+                nullable=True,
+                existing_server_default=sa.text("now()"),
+            )
+
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    conn = op.get_bind()
+    inspector = Inspector.from_engine(conn)  # type: ignore
+    table_names = inspector.get_table_names()
+    # ### commands auto generated by Alembic - please adjust! ###
+    if "variable" not in table_names:
+        return
+    with op.batch_alter_table("variable", schema=None) as batch_op:
+        if "created_at" in inspector.get_columns("variable"):
+            batch_op.alter_column(
+                "created_at",
+                existing_type=sa.TIMESTAMP(timezone=True),
+                nullable=False,
+                existing_server_default=sa.text("now()"),
+            )
+
+    # ### end Alembic commands ###

src/backend/base/langflow/services/database/models/variable/model.py

@@ -26,11 +26,11 @@ class Variable(VariableBase, table=True):
     )
     # name is unique per user
     created_at: datetime = Field(
-        sa_column=Column(DateTime(timezone=True), server_default=func.now(), nullable=False),
+        sa_column=Column(DateTime(timezone=True), server_default=func.now(), nullable=True),
         description="Creation time of the variable",
     )
     updated_at: Optional[datetime] = Field(
-        sa_column=Column(DateTime(timezone=True)),
+        sa_column=Column(DateTime(timezone=True), nullable=True),
         description="Last update time of the variable",
     )
     # foreign key to user table
@@ -39,7 +39,9 @@ class Variable(VariableBase, table=True):
 
 
 class VariableCreate(VariableBase):
-    type: Optional[str] = Field(None, description="Type of the variable")
+    created_at: Optional[datetime] = Field(default_factory=utc_now, description="Creation time of the variable")
+
+    updated_at: Optional[datetime] = Field(default_factory=utc_now, description="Creation time of the variable")
 
 
 class VariableRead(SQLModel):

src/backend/base/langflow/services/variable/service.py

@@ -3,13 +3,14 @@ from typing import TYPE_CHECKING, Optional, Union
 from uuid import UUID
 
 from fastapi import Depends
-from langflow.services.auth import utils as auth_utils
-from langflow.services.base import Service
-from langflow.services.database.models.variable.model import Variable
-from langflow.services.deps import get_session
 from loguru import logger
 from sqlmodel import Session, select
 
+from langflow.services.auth import utils as auth_utils
+from langflow.services.base import Service
+from langflow.services.database.models.variable.model import Variable, VariableCreate
+from langflow.services.deps import get_session
+
 if TYPE_CHECKING:
     from langflow.services.settings.service import SettingsService
 
@@ -93,14 +94,13 @@ class VariableService(Service):
         _type: str = "Generic",
         session: Session = Depends(get_session),
     ):
-        variable = Variable(
-            user_id=user_id,
+        variable_base = VariableCreate(
             name=name,
             type=_type,
             value=auth_utils.encrypt_api_key(value, settings_service=self.settings_service),
         )
+        variable = Variable.model_validate(variable_base, from_attributes=True, update={"user_id": user_id})
         session.add(variable)
         session.commit()
         session.refresh(variable)
         return variable
-        return variable