refactor: Update field_type in HandleInput to use SerializableFieldTypes enum

src/backend/base/langflow/inputs/input_mixin.py

@@ -26,7 +26,7 @@ SerializableFieldTypes = Annotated[FieldTypes, PlainSerializer(lambda v: v.value
 class BaseInputMixin(BaseModel, validate_assignment=True):
     model_config = ConfigDict(arbitrary_types_allowed=True)
 
-    field_type: Optional[SerializableFieldTypes | str] = Field(default=FieldTypes.TEXT)
+    field_type: Optional[SerializableFieldTypes] = Field(default=FieldTypes.TEXT)
 
     required: bool = False
     """Specifies if the field is required. Defaults to False."""

src/backend/base/langflow/inputs/inputs.py

@@ -1,6 +1,6 @@
 from typing import Any, Callable, Optional, Union
 
-from pydantic import Field, field_validator, model_validator
+from pydantic import Field, field_validator
 
 from langflow.inputs.validators import StrictBoolean
 from langflow.schema.data import Data
@@ -22,12 +22,6 @@ class HandleInput(BaseInputMixin, ListableInputMixin):
     input_types: list[str] = Field(default_factory=list)
     field_type: Optional[SerializableFieldTypes] = FieldTypes.OTHER
 
-    @model_validator(mode="after")
-    def validate_model_type(self):
-        # FieldType should be a string
-        self.field_type = " | ".join(self.input_types)
-        return self
-
 
 class PromptInput(BaseInputMixin, ListableInputMixin):
     field_type: Optional[SerializableFieldTypes] = FieldTypes.PROMPT