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77 lines
2.3 KiB
Markdown
77 lines
2.3 KiB
Markdown
---
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title: "Basic MQTT Example"
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description: ""
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ha_category: Custom Python Component Examples
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---
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<div class='note'>
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This example requires you to have the [MQTT integration](/integrations/mqtt/) up and running.
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</div>
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This is a simple hello world example to show the basics of using MQTT in a custom integration. To use this example, create the file `<config dir>/custom_components/hello_mqtt.py` and copy the below example code.
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This example follows a topic on MQTT and updates the state of an entity to the last message received on that topic. It will also register a service 'set_state' that will publish a message to the MQTT topic that we're listening to.
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```python
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import homeassistant.loader as loader
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# The domain of your component. Should be equal to the name of your component.
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DOMAIN = "hello_mqtt"
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# List of integration names (string) your integration depends upon.
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DEPENDENCIES = ["mqtt"]
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CONF_TOPIC = "topic"
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DEFAULT_TOPIC = "home-assistant/hello_mqtt"
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def setup(hass, config):
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"""Set up the Hello MQTT component."""
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mqtt = hass.components.mqtt
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topic = config[DOMAIN].get(CONF_TOPIC, DEFAULT_TOPIC)
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entity_id = "hello_mqtt.last_message"
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# Listener to be called when we receive a message.
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# The msg parameter is a Message object with the following members:
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# - topic, payload, qos, retain
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def message_received(msg):
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"""Handle new MQTT messages."""
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hass.states.set(entity_id, msg.payload)
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# Subscribe our listener to a topic.
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mqtt.subscribe(topic, message_received)
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# Set the initial state.
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hass.states.set(entity_id, "No messages")
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# Service to publish a message on MQTT.
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def set_state_service(call):
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"""Service to send a message."""
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mqtt.publish(topic, call.data.get("new_state"))
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# Register our service with Home Assistant.
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hass.services.register(DOMAIN, "set_state", set_state_service)
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# Return boolean to indicate that initialization was successfully.
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return True
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```
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Load the integration by adding the following to your `configuration.yaml`. When your integration is loaded, a new entity should popup and there should be a new service available to call.
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```yaml
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# configuration.yaml entry
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hello_mqtt:
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topic: some_mqtt/topic/here
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```
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You can call the service with example payload:
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```json
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{
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"new_state": "some new state"
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}
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```
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