Refactor code and fix custom_fields bug

src/backend/langflow/api/v1/validate.py

@@ -1,15 +1,10 @@
 from fastapi import APIRouter, HTTPException
-
-from langflow.api.v1.base import (
-    Code,
-    CodeValidationResponse,
-    ValidatePromptRequest,
-    PromptValidationResponse,
-    validate_prompt,
-)
+from langflow.api.v1.base import (Code, CodeValidationResponse,
+                                  PromptValidationResponse,
+                                  ValidatePromptRequest, validate_prompt)
 from langflow.template.field.base import TemplateField
-from loguru import logger
 from langflow.utils.validate import validate_code
+from loguru import logger
 
 # build router
 router = APIRouter(prefix="/validate", tags=["Validate"])
@@ -61,7 +56,11 @@ def get_old_custom_fields(prompt_request):
             # then we are dealing with the first prompt request after the node was created
             prompt_request.name = list(prompt_request.frontend_node.custom_fields.keys())[0]
 
-        old_custom_fields = prompt_request.frontend_node.custom_fields[prompt_request.name].copy()
+        old_custom_fields = prompt_request.frontend_node.custom_fields[prompt_request.name]
+        if old_custom_fields is None:
+            old_custom_fields = []
+
+        old_custom_fields = old_custom_fields.copy()
     except KeyError:
         old_custom_fields = []
     prompt_request.frontend_node.custom_fields[prompt_request.name] = []

src/backend/langflow/template/frontend_node/base.py

@@ -1,9 +1,10 @@
 import re
 from collections import defaultdict
-from typing import ClassVar, DefaultDict, Dict, List, Optional
+from typing import ClassVar, Dict, List, Optional
 
 from langflow.template.field.base import TemplateField
-from langflow.template.frontend_node.constants import CLASSES_TO_REMOVE, FORCE_SHOW_FIELDS
+from langflow.template.frontend_node.constants import (CLASSES_TO_REMOVE,
+                                                       FORCE_SHOW_FIELDS)
 from langflow.template.frontend_node.formatter import field_formatters
 from langflow.template.template.base import Template
 from langflow.utils import constants
@@ -45,7 +46,7 @@ class FrontendNode(BaseModel):
     name: str = ""
     display_name: str = ""
     documentation: str = ""
-    custom_fields: Optional[DefaultDict[str, List[str]]] = defaultdict(list)
+    custom_fields: Optional[Dict] = defaultdict(list)
     output_types: List[str] = []
     full_path: Optional[str] = None
     field_formatters: FieldFormatters = Field(default_factory=FieldFormatters)