Push - Let Home Assistant Control Visuals

In this scenario, Home Assistant centrally updates all Visuals in any of your devices whenever the state of an Effector changes.

Overview

These are the tasks the central automation script must perform:

1. Device State Updates:
   When the state of a device (the Effector) changes, all Visuals representing that device must update accordingly.

   Example: when a plug is turned off, then all Visuals representing this plug in any of your devices should change from green to red.

2. State Initialization:
   When a device with a relevant Visual becomes available, it must be initialized so that its Visuals show the correct state.

   Else, the device could show a random state until the next time the state changes.

Managing Automations

Home Assistant maintains a central automation script in /config/automations.yaml.

This file is not directly accessible through the Home Assistant UI unless you install separate add-ons like File Editor or Studio Code Server, but this is not necessary as there are better and safer ways to edit it.

What Are Automations Anyway?

Automations leverage the true power in Home Assistant as they allow you to teach Home Assistant what it should do automatically when certain things occur.

This allows you to compose automations that involve multiple devices:

• If sensor A detects a temperature above B, turn on device C, i.e. a fan or air conditioning system.
• If a button is pressed on device X, toggle plug Y, effectively making the button a remote control that is paired to the plug.

Accessing Automations

To view all automations:

1. Navigate to Settings → Automations & Scenes.
2. Click Create Automation to add a new automation.

Initially, this list is empty, but you can add any number of automation tasks.

How Automations Work

Home Assistant stores all automations in a hidden file: /config/automations.yaml. This file is automatically managed and updated when you create or modify automations via the UI.

Here is how it works:

1. Code in automations.yaml:
   Home Assistant reads automations.yaml at startup and reloads it when changes are made.
2. Adding New Automation:
   Creating a new automation via the UI adds the corresponding code to automations.yaml. This ensures consistency while preventing errors.
3. Wizard for Simplicity:
   The Create Automation wizard guides you through setting to compose automations via dropdown menus and simple prompts.
4. Viewing & Editing Automations:
   • Automations can be found under Settings → Automations & Scenes.
   • Clicking an automation lets you edit it via the wizard and its simple controls.
   • Advanced users can access the three-dot menu in the top-right corner to disable, delete, or Edit in YAML.

Working With The Real Code

The built-in wizard is great for simple automation tasks, but you’ll soon hit its limitations, and also the wizard controls can sometimes be more confusing than helpful.

Accessing Source Code

When you click Edit in Yaml, you get to see the raw content of automations.yaml after all. You now can view the source code that the wizard has created for you, and even edit and change it.

You are, however, only working with the portion of automations.yaml that belong to your automation, and the UI shields you from other code. This is much clearer and protects you from accidentally damaging other automations.

Understanding Automations

Before you can fully leverage the power of Home Assistant automations, you need a basic understanding of how the code in automations really work.

Using the simple wizard is not enough and too limited for most tasks.

Sample Automation

Create a simple automation using the wizard. Then click Edit in YAML and look at the raw YAML code.

For example, I created an automation that toggles a plug when a button is pressed. Here is the raw YAML code:

alias: Toggle Plug T34-19
description: When push button is pressed, toggle state of plug
mode: single
triggers:
  - type: turned_on
    device_id: d93e239b5f04ccdd3b671c70303a45ab
    entity_id: 9490a273345f25f05d90e72c42bb2f20
    domain: binary_sensor
conditions: []
actions:
  - type: toggle
    device_id: 05a1d541fac7c7fc3d6127e1af0b0116
    entity_id: 8db7a92b4ce6e0168ccb4b3e7f9908ea
    domain: switch

Understanding Code

Now try and make sense of the code.

Here are two hints that help you simplify the wizard-generated code significantly:

• YAML:
  Automations use the same simple YAML language that you already know from ESPHome. The same rules apply:
  • tree structure, correct indenting is crucial.
  • key-value pairs, key ends with :
• Entity ID:
  To reference particular devices, you use the unique device IDs.
  • GUIDs the wizard uses cryptic GUID numbers
  • Entity ID: instead, use Entity IDs that you use everywhere else in the Home Assistant UI anyway.

Here is a much more readable version for the same automation:

alias: Control Fan
description: Toggle the fan when the push button is pressed
triggers:
  - entity_id: binary_sensor.push_button_pushbutton1
    to: "on"
    trigger: state
actions:
  - target:
      entity_id: switch.plug_t34_38_switch_1
    action: switch.toggle
    data: {}
mode: single

Testing Code

Copy the original wizard-generated code to an editor for backup, then replace the code with your simplified version. Save it, and test whether Home Assistant still correctly executes the automation.

This may be a mixed experience of trial and error, but eventually you get the idea, and it becomes evident how simple automation scripts often are:

• When? trigger: defines when an automation should execute
• What? action: defines the changes this automation should invoke

Automation Code Explained

By applying this know-how to the sample automation, you can now easily “decipher” it:

• Documentation:
  alias: and description: are just comments that help you better understand what the code does when you revisit it in a few weeks.
• When?
  triggers: defines when this automation should execute: it executes when the state of device with Entity ID binary_sensor.push_button_pushbutton1 changes to on (when the push button is pressed).
• What?
  actions: defines what Home Assistant should do when the trigger condition is met: the device with the Entity ID switch.plug_t34_38_switch_1 (a plug) is instructed to perform the action switch.toggle: when the plug was on, it is now off, and vice versa.

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