Params

Params is a plain Python class — no magic, no metaclass, no Pydantic. Just a base class that tells FuncToWeb to expand its fields into the form automatically.

Basic Usage

from typing import Annotated
from pydantic import Field
from func_to_web import run, Params
from func_to_web.types import Email

class UserData(Params):
    name:  Annotated[str, Field(min_length=2, max_length=50)]
    email: Email
    age:   int = 18

def basic(data: UserData):
    return f"Created: {data.name}, {data.email}, {data.age}"

run(basic)

FuncToWeb expands UserData into three individual form fields — name, email, and age — exactly as if you had declared them directly on the function.

Basic Usage

Reusing Across Functions

The main use case for Params is sharing the same fields across multiple functions without repeating yourself:

from typing import Annotated
from pydantic import Field
from func_to_web import run, Params
from func_to_web.types import Email

class UserData(Params):
    name:  Annotated[str, Field(min_length=2, max_length=50)]
    email: Email

def create_user(data: UserData):
    return f"Created: {data.name}"

def edit_user(id: int, data: UserData):
    return f"Edited user {id}: {data.name}"

run([create_user, edit_user])

Change UserData once and it updates every function that uses it.

Creating Users Editing Users

It's Just a Class

Params subclasses are plain Python classes. You can add methods, properties, class variables, or any logic you want:

from func_to_web import run, Params
from func_to_web.types import Email

class UserData(Params):
    name:  str
    email: Email

    @property
    def display(self):
        return f"{self.name} <{self.email}>"

def just_a_class(data: UserData):
    return f"Created: {data.display}"

run(just_a_class)

FuncToWeb only reads the type-annotated fields — everything else is ignored by the form renderer.

It's Just a Class

Mixing Params with Other Parameters

from typing import Annotated
from pydantic import Field
from func_to_web import run, Params

class Address(Params):
    street: str
    city:   str
    zip:    Annotated[str, Field(pattern=r'^\d{5}$')]

def mixing(user_id: int, address: Address, notify: bool = True):
    return f"User {user_id} registered at {address.city}"

run(mixing)

Default Values

Default values work exactly as in any Python class:

from func_to_web import run, Params

class Settings(Params):
    theme:    str = "dark"
    language: str = "en"
    retries:  int = 3

def defaults(settings: Settings):
    return f"Theme: {settings.theme}, Lang: {settings.language}"

run(defaults)