# Write a custom component for Home Assistant > This is a dummy component which integrates with binary sensor, lock, sensor and switch platforms for demonstrating the development of custom components used in Home Assistant. ## Development 1. Setup development environment as described in the following URL: `https://developers.home-assistant.io/docs/development_environment/` 2. Generate the skeleton codes for integration by executing the following command: `python3 -m script.scaffold integration` An interative Q&A session then starts. When it finishes, it will generate the skeleton codes. ```shell What is the domain? > dummy_garage What is the name of your integration? > Dummy Garage What is your GitHub handle? > @adafycheng What PyPI package and version do you depend on? Leave blank for none. > How will your integration gather data? Valid values are assumed_state, calculated, cloud_polling, cloud_push, local_polling, local_push More info @ https://developers.home-assistant.io/docs/creating_integration_manifest#iot-class > local_polling Does Home Assistant need the user to authenticate to control the device/service? (yes/no) [yes] > no Is the device/service discoverable on the local network? (yes/no) [no] > no Is this a helper integration? (yes/no) [no] > yes Can the user authenticate the device using OAuth2? (yes/no) [no] > no Scaffolding integration for the dummy_garage integration... Writing tests/components/dummy_garage/__init__.py Writing homeassistant/components/dummy_garage/const.py Writing homeassistant/components/dummy_garage/manifest.json Writing homeassistant/components/dummy_garage/__init__.py Updating dummy_garage manifest: {'codeowners': ['@adafycheng'], 'iot_class': 'local_polling'} Scaffolding config_flow_helper for the dummy_garage integration... Writing homeassistant/components/dummy_garage/const.py Writing homeassistant/components/dummy_garage/__init__.py Writing homeassistant/components/dummy_garage/sensor.py Writing homeassistant/components/dummy_garage/config_flow.py Writing tests/components/dummy_garage/test_config_flow.py Writing tests/components/dummy_garage/test_init.py Updating dummy_garage manifest: {'config_flow': True} Updating dummy_garage strings: ['config', 'options'] Running hassfest to pick up new information. Running gen_requirements_all to pick up new information. Running script/translations_develop to pick up new translation strings. ************************** Integration code has been generated Added the following files: - homeassistant/components/dummy_garage/config_flow.py - homeassistant/components/dummy_garage/manifest.json - homeassistant/components/dummy_garage/const.py - homeassistant/components/dummy_garage/sensor.py - homeassistant/components/dummy_garage/__init__.py Added the following tests: - tests/components/dummy_garage/test_init.py - tests/components/dummy_garage/test_config_flow.py The next step is to look at the files and deal with all areas marked as TODO. ``` 3. In this integration, since we create the entities by configuration, therefore we clear most of the codes `in __init__.py`. 4. For each of the platforms, i. Define the **PLATFORM_SCHEMA** (mandatoriness and data type) for getting the inputs from configuration.yaml. ```python import voluptuous as vol from homeassistant.components.sensor import ( PLATFORM_SCHEMA, SensorDeviceClass, SensorEntity, SensorStateClass, ) DEFAULT_NAME = "Dummy Garage - Sensor" PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend( { vol.Required(CONF_MAC): cv.string, vol.Optional(CONF_NAME, default=DEFAULT_NAME): cv.string, } ) ``` ii. Add a `async_setup_platform` function to be called when the platform is being setup. In this function, the entity will be created and added to Home Assistant. ```python async def async_setup_platform( hass: HomeAssistant, config: ConfigType, add_entities: AddEntitiesCallback, discovery_info: DiscoveryInfoType | None = None, ) -> None: """Set up the sensor platform.""" name = config[CONF_NAME] mac_addr = config[CONF_MAC] add_entities([DummyGarageSensor(mac_addr, name)], True) ``` iii. Create a class with the Entity class corresponding to the platform as the input parameter. - The `__init__` function is the constructor of the class. - The `name` function returns as the Name of the entity shown in the Home Assistant Web Application. - The `unique_id` function returns as the unique ID of the entity. I transform the input MAC address to a unique ID. ```python class DummyGarageSensor(SensorEntity): """Representation of a Sensor.""" def __init__(self, mac, name) -> None: super().__init__() self._mac = mac self._name = name self._attr_name = name self._attr_native_unit_of_measurement = TEMP_CELSIUS self._attr_device_class = SensorDeviceClass.TEMPERATURE self._attr_state_class = SensorStateClass.MEASUREMENT @property def name(self) -> str: """Return the name of the switch.""" return self._name @property def unique_id(self) -> str: """Return a unique, Home Assistant friendly identifier for this entity.""" return self._mac.replace(":", "") def update(self) -> None: """Fetch new state data for the sensor. This is the only method that should fetch new data for Home Assistant. """ self._attr_native_value = 23 ``` ## Deployment 1. Copy the directory homeassistant/components/dummy_garage/ to the Home Assistant Core /homeassistant/components/. 2. Add configuration for the desired entities in the `config/configuration.yaml` file. ```yaml binary_sensor: - platform: dummy_garage name: "Dummy Car Presence" mac: "12:34:12:34:12:34" device_class: "presence" lock: - platform: dummy_garage name: "Dummy Garage Lock" mac: "EF:EF:EF:EF:EF:EF" switch: - platform: dummy_garage name: "Dummy Garage Switch" mac: "AB:AB:AB:CD:CD:CD" sensor: - platform: dummy_garage name: "Dummy Temperature" mac: "56:34:12:90:78:56" ``` 3. For testing purpose, add automations for opening and closing the garage door in the `config/automations.yaml` file. Remember to change the values of `entity_id` if they are different from this example. ```yaml - id: open_garage alias: "Open Garage Door" trigger: - platform: time_pattern minutes: 5 - platform: time_pattern minutes: 15 - platform: time_pattern minutes: 25 - platform: time_pattern minutes: 35 - platform: time_pattern minutes: 45 - platform: time_pattern minutes: 55 action: - service: lock.unlock target: entity_id: lock.dummy_garage_lock - delay: 00:00:10 - service: switch.turn_on target: entity_id: switch.dummy_garage_switch - id: close_garage alias: "Close Garage Door" trigger: - platform: time_pattern minutes: 10 - platform: time_pattern minutes: 20 - platform: time_pattern minutes: 30 - platform: time_pattern minutes: 40 - platform: time_pattern minutes: 50 - platform: time_pattern minutes: 0 action: - service: switch.turn_off target: entity_id: switch.dummy_garage_switch - delay: 00:00:10 - service: lock.lock target: entity_id: lock.dummy_garage_lock ``` 4. Start Home Assistant Core: `hass -c config` ## Verification 1. Login Home Assistant Web Application. ![HA Web Application](https://cdn.hashnode.com/res/hashnode/image/upload/v1650529492394/DtRMY5qJO.png) 2. Check that the entities are created. ![Dummy Garage entities](https://cdn.hashnode.com/res/hashnode/image/upload/v1650529505791/y7OL18YEn.png) 3. Add the entities at the **Overview** tab. 4. Trigger the ***Open Garage Door*** action and observe the door lock and switch status. ![Dummy garage door open](https://cdn.hashnode.com/res/hashnode/image/upload/v1650529519663/pj9s0AKp0.png) 5. Trigger the ***Close Garage Door*** action and observe the door lock and switch status. ![Dummy garage door close](https://cdn.hashnode.com/res/hashnode/image/upload/v1650529540860/pONloCzbU.png) ## Acknowledgements 1. [Set up Development Environment for Home Assistant](https://developers.home-assistant.io/docs/development_environment/). 2. [Home Assistant Entities](https://developers.home-assistant.io/docs/core/entity). 3. [GitHub Source Code](https://github.com/adafycheng/home-assistant-components/tree/main/dummy-garage).