# Flow to trigger when a boolean changes state in Home Assistant

**URL:** <https://discourse.nodered.org/t/flow-to-trigger-when-a-boolean-changes-state-in-home-assistant/55248>\
**Category:** General\
**Created:** [15 December 2021 21:07 UTC](https://discourse.nodered.org/t/flow-to-trigger-when-a-boolean-changes-state-in-home-assistant/55248 "2021-12-15T21:07:05Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![neilsonwheels](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/neilsonwheels/32/52311_2.png) [@neilsonwheels](https://discourse.nodered.org/u/neilsonwheels)\
**Post date:** [15 December 2021 21:07 UTC](https://discourse.nodered.org/t/flow-to-trigger-when-a-boolean-changes-state-in-home-assistant/55248/1 "2021-12-15T21:07:05Z")

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I'm looking for a flow in my Home Assistant system that will trigger a Google TTS node when a boolean switches state from ON-OFF or OFF-ON. I want this to be a one time occurence at the point when the state changes. I hope that makes sense.

I'm just not sure which node would achieve this.

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**Author:** ![E1cid](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/e1cid/32/77971_2.png) [@E1cid](https://discourse.nodered.org/u/E1cid)\
**Post date:** [15 December 2021 21:24 UTC](https://discourse.nodered.org/t/flow-to-trigger-when-a-boolean-changes-state-in-home-assistant/55248/2 "2021-12-15T21:24:52Z")

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Most here do not use HA, so you may find a better answer on the HA forum, they have a node-red section.

To give you some sort of direction. You would use a state change node(educated guess), then a rbe/filter node(this will allow only messages on a change of property), followed by a fuction node or change node or a template node to create your tts message object, and finally your tts node.

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**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [13 February 2022 21:25 UTC](https://discourse.nodered.org/t/flow-to-trigger-when-a-boolean-changes-state-in-home-assistant/55248/3 "2022-02-13T21:25:34Z")

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