Request

from pymediate import Request

class Request[ResponseT]: ...

Base class for all requests, carrying the expected response type as its type parameter. Inheriting from Request[ResponseType] is what enables response-type inference at every mediator.send() call site and PyMediate's runtime validation of handlers.

The response type is extracted and registered automatically when the subclass is defined (via __init_subclass__) — at import time, with no per-request overhead.

Type parameters

Usage

With dataclasses (recommended):

from dataclasses import dataclass
from pymediate import Request

@dataclass
class UserCreatedResponse:
    user_id: int
    username: str

@dataclass
class CreateUserRequest(Request[UserCreatedResponse]):
    username: str
    email: str

With regular classes:

class CreateUserRequest(Request[UserCreatedResponse]):
    def __init__(self, name: str, email: str):
        self.name = name
        self.email = email

See also

• Handler — the class that processes requests
• Requests and responses guide — message design patterns
• Dataclasses with PyMediate — dataclass-specific patterns