refactor: Update field input classes for different data types

This commit adds field input classes for different data types in the `inputs.py` file. The purpose of this change is to improve the organization and separation of concerns in the codebase. Each input class specifies the field type and provides default values or options where applicable. This update enhances the maintainability and extensibility of the codebase.

src/backend/base/langflow/template/field/input_mixin.py

@@ -1,7 +1,7 @@
 from enum import Enum
-from typing import Any, Optional
+from typing import Annotated, Any, Optional
 
-from pydantic import BaseModel, ConfigDict, Field, field_validator
+from pydantic import BaseModel, ConfigDict, Field, PlainSerializer, field_validator
 
 from langflow.field_typing.range_spec import RangeSpec
 
@@ -18,11 +18,14 @@ class FieldTypes(str, Enum):
     PROMPT = "Prompt"
 
 
+SerializableFieldTypes = Annotated[FieldTypes, PlainSerializer(lambda v: v.value, return_type=str)]
+
+
 # Base mixin for common input field attributes and methods
 class BaseInputMixin(BaseModel):
     model_config = ConfigDict(arbitrary_types_allowed=True)
 
-    field_type: Optional[FieldTypes] = 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/template/field/inputs.py

@@ -1,46 +1,59 @@
-from pydantic import SecretStr
+from typing import Callable, Optional, Union
 
-from langflow.field_typing.constants import NestedDict
-from langflow.template.field.base import Input
+from pydantic import Field
+
+from langflow.template.field.input_mixin import (
+    BaseInputMixin,
+    DatabaseLoadMixin,
+    DropDownMixin,
+    FieldTypes,
+    FileMixin,
+    ListableInputMixin,
+    RangeMixin,
+)
 
 
-class StrInput(Input):
-    field_type: str | type | None = str
+class PromptInput(BaseInputMixin, ListableInputMixin):
+    field_type = FieldTypes.PROMPT
 
 
-class SecretStrInput(Input):
-    field_type: str | type | None = SecretStr
-    password = True
+# Applying mixins to a specific input type
+class StrInput(BaseInputMixin, ListableInputMixin):  # noqa: F821
+    field_type = FieldTypes.TEXT
+    multiline: bool = Field(default=False)
+    """Defines if the field will allow the user to open a text editor. Default is False."""
 
 
-class IntInput(Input):
-    field_type: str | type | None = int
+class SecretStrInput(BaseInputMixin, DatabaseLoadMixin):
+    field_type = FieldTypes.PASSWORD
+    password: bool = Field(default=True)
 
 
-class FloatInput(Input):
-    field_type: str | type | None = float
+class IntInput(BaseInputMixin, ListableInputMixin, RangeMixin):
+    field_type = FieldTypes.INTEGER
 
 
-class BoolInput(Input):
-    field_type: str | type | None = bool
+class FloatInput(BaseInputMixin, ListableInputMixin, RangeMixin):
+    field_type = FieldTypes.FLOAT
 
 
-class NestedDictInput(Input):
-    field_type: str | type | None = NestedDict
+class BoolInput(BaseInputMixin, ListableInputMixin):
+    field_type = FieldTypes.BOOLEAN
 
 
-class DictInput(Input):
-    field_type: str | type | None = dict
+class NestedDictInput(BaseInputMixin, ListableInputMixin):
+    field_type = FieldTypes.NESTED_DICT
 
 
-class ListInput(Input):
-    is_list = True
+class DictInput(BaseInputMixin, ListableInputMixin):
+    field_type = FieldTypes.DICT
 
 
-class DropdownInput(Input):
-    field_type: str | type | None = str
-    options = []
+class DropdownInput(BaseInputMixin, DropDownMixin):
+    field_type = FieldTypes.TEXT
+    options: Optional[Union[list[str], Callable]] = None
+    """List of options for the field. Only used when is_list=True. Default is an empty list."""
 
 
-class FileInput(Input):
-    field_type: str | type | None = str
+class FileInput(BaseInputMixin, ListableInputMixin, FileMixin):
+    field_type = FieldTypes.FILE