refactor: add model validator to FlowHeader model and fix response handling (#5355)

* refactor: streamline imports and enhance flow header response handling in flows.py

- Consolidated import statements for better readability.
- Updated the response structure in the  function to utilize  for improved data validation and consistency.

* refactor: enhance FlowHeader model with detailed field descriptions and validation

- Updated FlowHeader model to include field descriptions for better clarity and documentation.
- Introduced a model validator to ensure data integrity before processing.
- Streamlined import statements for improved readability.

---------

Co-authored-by: Lucas Oliveira <62335616+lucaseduoli@users.noreply.github.com>

src/backend/base/langflow/api/v1/flows.py

@@ -17,13 +17,7 @@ from fastapi_pagination.ext.sqlalchemy import paginate
 from sqlmodel import and_, col, select
 from sqlmodel.ext.asyncio.session import AsyncSession
 
-from langflow.api.utils import (
-    CurrentActiveUser,
-    DbSession,
-    cascade_delete_flow,
-    remove_api_keys,
-    validate_is_component,
-)
+from langflow.api.utils import CurrentActiveUser, DbSession, cascade_delete_flow, remove_api_keys, validate_is_component
 from langflow.api.v1.schemas import FlowListCreate
 from langflow.initial_setup.constants import STARTER_FOLDER_NAME
 from langflow.services.database.models.flow import Flow, FlowCreate, FlowRead, FlowUpdate
@@ -221,17 +215,7 @@ async def read_flows(
             if remove_example_flows and starter_folder_id:
                 flows = [flow for flow in flows if flow.folder_id != starter_folder_id]
             if header_flows:
-                return [
-                    {
-                        "id": flow.id,
-                        "name": flow.name,
-                        "folder_id": flow.folder_id,
-                        "is_component": flow.is_component,
-                        "description": flow.description,
-                        "endpoint_name": flow.endpoint_name,
-                    }
-                    for flow in flows
-                ]
+                return [FlowHeader.model_validate(flow, from_attributes=True) for flow in flows]
             return flows
 
         stmt = stmt.where(Flow.folder_id == folder_id)

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

@@ -9,7 +9,7 @@ import emoji
 from emoji import purely_emoji
 from fastapi import HTTPException, status
 from loguru import logger
-from pydantic import BaseModel, field_serializer, field_validator
+from pydantic import BaseModel, field_serializer, field_validator, model_validator
 from sqlalchemy import Text, UniqueConstraint
 from sqlmodel import JSON, Column, Field, Relationship, SQLModel
 
@@ -198,30 +198,21 @@ class FlowRead(FlowBase):
 
 
 class FlowHeader(BaseModel):
-    """Model representing a header for a flow - Without the data.
+    """Model representing a header for a flow - Without the data."""
 
-    Attributes:
-    -----------
-    id : UUID
-        Unique identifier for the flow.
-    name : str
-        The name of the flow.
-    folder_id : UUID | None, optional
-        The ID of the folder containing the flow. None if not associated with a folder.
-    is_component : bool | None, optional
-        Flag indicating whether the flow is a component.
-    endpoint_name : str | None, optional
-        The name of the endpoint associated with this flow.
-    description : str | None, optional
-        A description of the flow.
-    """
+    id: UUID = Field(description="Unique identifier for the flow")
+    name: str = Field(description="The name of the flow")
+    folder_id: UUID | None = Field(
+        None, description="The ID of the folder containing the flow. None if not associated with a folder"
+    )
+    is_component: bool | None = Field(None, description="Flag indicating whether the flow is a component")
+    endpoint_name: str | None = Field(None, description="The name of the endpoint associated with this flow")
+    description: str | None = Field(None, description="A description of the flow")
 
-    id: UUID
-    name: str
-    folder_id: UUID | None = None
-    is_component: bool | None = None
-    endpoint_name: str | None = None
-    description: str | None = None
+    @model_validator(mode="before")
+    @classmethod
+    def validate_flow_header(cls, data: dict):
+        return data
 
 
 class FlowUpdate(SQLModel):