# Trigger & block in subflow

**URL:** <https://discourse.nodered.org/t/trigger-block-in-subflow/60735>\
**Category:** General\
**Tags:** home-assistant\
**Created:** [3 April 2022 18:01 UTC](https://discourse.nodered.org/t/trigger-block-in-subflow/60735 "2022-04-03T18:01:43Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![zimcube](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/zimcube/32/59511_2.png) [@zimcube](https://discourse.nodered.org/u/zimcube)\
**Post date:** [3 April 2022 18:01 UTC](https://discourse.nodered.org/t/trigger-block-in-subflow/60735/1 "2022-04-03T18:01:44Z")

</div>

Can I put a `trigger & block` node inside a subflow? My guess is each time a new message comes in, a new instance of the subflow will be created.

- What mental model should I have of a "node". Is it analogous to an instance of a class or more analogous to a singleton?
- Can I solve this inside a subflow by having a global `lock` on the specific door (entity\_id)?
  - does this exist already as a contrib?

## Context

I am running Home Assistant and have multiple (2) garage doors. When the door starts closing it emits a `closing` state event. The `Close Door with retries` subflow will retry closing the door 3 times and then give up and send me a notification to my phone.

Inside the `Close Door with retries` subflow, after it detects the closing has failed (door state is `open`) the subflow will tell Home Assistant to close the door, which then triggers the `state_changed` node again. That's why I have the trigger & block node before the subflow.

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/a/5/a5ad3588631faa73e75ef5f58bfaaf610bc5c5e9.png)

I am new to Node-RED and Javascript.

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<div class="post-metadata">

**Author:** ![zimcube](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/zimcube/32/59511_2.png) [@zimcube](https://discourse.nodered.org/u/zimcube)\
**Post date:** [3 April 2022 18:15 UTC](https://discourse.nodered.org/t/trigger-block-in-subflow/60735/2 "2022-04-03T18:15:33Z")

</div>

Okay, my guess was wrong on this. I built  
 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/e/a/eaa27c415e2008e52ecd146dc076e2c370d2de7c.png)

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/f/a/fa65d1339152e207db39f16147b2bbc001bdc068.png)

```auto
[{"id":"1c84d314d704e11d","type":"subflow","name":"Subflow 1","info":"","in":[{"x":180,"y":180,"wires":[{"id":"8efde020a7b4e6d5"}]}],"out":[]},{"id":"4b1dc2cbb648a042","type":"delay","z":"1c84d314d704e11d","name":"","pauseType":"delay","timeout":"1","timeoutUnits":"seconds","rate":"1","nbRateUnits":"1","rateUnits":"second","randomFirst":"1","randomLast":"5","randomUnits":"seconds","drop":false,"allowrate":false,"outputs":1,"x":600,"y":180,"wires":[["26aeeaa0eef3f90e"]]},{"id":"e9ba2383658a2116","type":"debug","z":"1c84d314d704e11d","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","statusVal":"","statusType":"auto","x":610,"y":120,"wires":[]},{"id":"26aeeaa0eef3f90e","type":"change","z":"1c84d314d704e11d","name":"","rules":[{"t":"set","p":"reset","pt":"msg","to":"true","tot":"bool"}],"action":"","property":"","from":"","to":"","reg":false,"x":820,"y":180,"wires":[["8efde020a7b4e6d5"]]},{"id":"8efde020a7b4e6d5","type":"trigger","z":"1c84d314d704e11d","name":"","op1":"","op2":"0","op1type":"pay","op2type":"str","duration":"0","extend":false,"overrideDelay":false,"units":"ms","reset":"","bytopic":"topic","topic":"payload","outputs":1,"x":380,"y":180,"wires":[["4b1dc2cbb648a042","e9ba2383658a2116"]]}]

```

The `trigger & block` node handles each `msg.payload` and performs the way I want. This means that each node you drop is a singleton object. In hind sight this makes sense: in order for trigger & block to work it must be long lived, which means the subflow is also long lived.

---

<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [17 April 2022 18:16 UTC](https://discourse.nodered.org/t/trigger-block-in-subflow/60735/3 "2022-04-17T18:16:02Z")

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