# Problem passing topic.trigger to JOIN node

**URL:** <https://discourse.nodered.org/t/problem-passing-topic-trigger-to-join-node/34745>\
**Category:** General\
**Created:** [24 October 2020 13:00 UTC](https://discourse.nodered.org/t/problem-passing-topic-trigger-to-join-node/34745 "2020-10-24T13:00:03Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![woiptcs](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/woiptcs/32/30650_2.png) [@woiptcs](https://discourse.nodered.org/u/woiptcs)\
**Post date:** [24 October 2020 13:00 UTC](https://discourse.nodered.org/t/problem-passing-topic-trigger-to-join-node/34745/1 "2020-10-24T13:00:04Z")

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Hello ,

I'm using JOIN node to join multiple JSON Objects in to a merged object. This works properly.  
But I need to use and external trigger every "5 minutes" to generate the output of the "join" node.  
I'm using a simple scheduled "inject" as trigger.

From node-red-contrib-join documentation I can trigger the join fuction passing a msg with topic "trigger" but it allways get a error from the join-node output...

Anyone can help to know how to do this ?

Thank you in advance !

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**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [24 October 2020 13:48 UTC](https://discourse.nodered.org/t/problem-passing-topic-trigger-to-join-node/34745/2 "2020-10-24T13:48:33Z")

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Don't use node-red-contrib-join, it has not been updated for four years and probably therefore will have problems. Can't you use the node-red core Join node? It should do what you want.

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**Author:** ![woiptcs](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/woiptcs/32/30650_2.png) [@woiptcs](https://discourse.nodered.org/u/woiptcs)\
**Post date:** [24 October 2020 14:05 UTC](https://discourse.nodered.org/t/problem-passing-topic-trigger-to-join-node/34745/3 "2020-10-24T14:05:59Z")

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Hello ,  
I've been able to do it , but the problem is at starttime, i need to initialise all inputs of JOIN node rather UI or other sources to get a complete joined merged Object.  
Is any posibility to keep/save values between reboots, or flow restarts?  
May I use set-state get-state nodes ?

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**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [24 October 2020 14:20 UTC](https://discourse.nodered.org/t/problem-passing-topic-trigger-to-join-node/34745/4 "2020-10-24T14:20:24Z")

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Is this the same question as on the [other thread](https://discourse.nodered.org/t/refresh-ui-avoiding-msg-loops/34550)? If so then please close one of them and keep the conversation to one thread. I have already suggested using retained topics in the other thread.

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**Author:** ![woiptcs](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/woiptcs/32/30650_2.png) [@woiptcs](https://discourse.nodered.org/u/woiptcs)\
**Post date:** [24 October 2020 14:23 UTC](https://discourse.nodered.org/t/problem-passing-topic-trigger-to-join-node/34745/5 "2020-10-24T14:23:09Z")

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ok , Colin sorry about that.  
With retained topic you mean configure MQTT OUT node with Retain set to TRUE ?

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<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [24 October 2020 14:46 UTC](https://discourse.nodered.org/t/problem-passing-topic-trigger-to-join-node/34745/6 "2020-10-24T14:46:04Z")

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Yes, or pass it in the message as described in the node help. But first if you don't know what retained topics are then look at this [guide to mqtt.](https://www.hivemq.com/mqtt-essentials/)

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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:** [23 December 2020 14:46 UTC](https://discourse.nodered.org/t/problem-passing-topic-trigger-to-join-node/34745/7 "2020-12-23T14:46:12Z")

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