ha-entity-platforms

Home Assistant Entity Platforms

Platform Setup Pattern

Every platform implements async_setup_entry:

"""Sensor platform for {Name}."""
from __future__ import annotations

from homeassistant.core import HomeAssistant
from homeassistant.helpers.entity_platform import AddEntitiesCallback

# {Name}ConfigEntry is the `type {Name}ConfigEntry = ConfigEntry[{Name}Coordinator]` alias defined in __init__.py (see ha-integration-scaffold).
from . import {Name}ConfigEntry
from .coordinator import {Name}Coordinator


async def async_setup_entry(
    hass: HomeAssistant,
    entry: {Name}ConfigEntry,
    async_add_entities: AddEntitiesCallback,
) -> None:
    """Set up sensors from a config entry."""
    coordinator = entry.runtime_data

    entities = []
    for device_id in coordinator.get_device_ids():
        for description in SENSOR_DESCRIPTIONS:
            entities.append({Name}Sensor(coordinator, description, device_id))

    async_add_entities(entities)

Entity Description Pattern

Use EntityDescription dataclasses for declarative definitions:

from dataclasses import dataclass
from collections.abc import Callable
from typing import Any

from homeassistant.components.sensor import (
    SensorDeviceClass,
    SensorEntity,
    SensorEntityDescription,
    SensorStateClass,
)
from homeassistant.const import PERCENTAGE, UnitOfTemperature


@dataclass(frozen=True, kw_only=True)
class {Name}SensorDescription(SensorEntityDescription):
    """Describe a {Name} sensor."""
    value_fn: Callable[[dict[str, Any]], Any]


SENSOR_DESCRIPTIONS: tuple[{Name}SensorDescription, ...] = (
    {Name}SensorDescription(
        key="temperature",
        translation_key="temperature",
        device_class=SensorDeviceClass.TEMPERATURE,
        state_class=SensorStateClass.MEASUREMENT,
        native_unit_of_measurement=UnitOfTemperature.CELSIUS,
        value_fn=lambda data: data.get("temperature"),
    ),
    {Name}SensorDescription(
        key="humidity",
        translation_key="humidity",
        device_class=SensorDeviceClass.HUMIDITY,
        state_class=SensorStateClass.MEASUREMENT,
        native_unit_of_measurement=PERCENTAGE,
        value_fn=lambda data: data.get("humidity"),
    ),
)