# General

**URL:** https://discourse.nodered.org/c/general/7.md?page=807

[Latest](https://discourse.nodered.org/latest.md) · [Categories](https://discourse.nodered.org/categories.md) · [Tags](https://discourse.nodered.org/tags.md)

**Page:** 808

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## [Help with function node](https://discourse.nodered.org/t/help-with-function-node/20333)

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**Author:** [@niclas.w82](https://discourse.nodered.org/u/niclas.w82)\
**Replies:** 2\
**Last updated:** [14 January 2020 20:35 UTC](https://discourse.nodered.org/t/help-with-function-node/20333 "2020-01-14T20:35:48Z")

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HI. Have tried to get this work for a while now. Have read the documentation on the function node but I don't get how to solve this. I want multiple expressions I one node with an output for each expression.

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## [Api for subflows](https://discourse.nodered.org/t/api-for-subflows/20325)

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**Author:** [@jacyuan](https://discourse.nodered.org/u/jacyuan)\
**Replies:** 4\
**Last updated:** [14 January 2020 20:13 UTC](https://discourse.nodered.org/t/api-for-subflows/20325 "2020-01-14T20:13:22Z")

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Hi, I'm trying to manage nodered with admin api endpoints. If I want to import an existing flow (not all flows but only some selected ones) from another nodered instance : I do a http get from the source nodered serv…

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## [Help with function - yes an another noob -](https://discourse.nodered.org/t/help-with-function-yes-an-another-noob/20320)

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**Author:** [@Panos](https://discourse.nodered.org/u/Panos)\
**Replies:** 3\
**Last updated:** [14 January 2020 18:16 UTC](https://discourse.nodered.org/t/help-with-function-yes-an-another-noob/20320 "2020-01-14T18:16:36Z")

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I am trying to set a function to compare the value of a DHT11 sensor (temperature) with a set point and if the ui-switch is off do nothing. If the temperature is bellow the setpoint and the ui switch is on then send msg …

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## [Configurations lost while creating a dynamic node and flow](https://discourse.nodered.org/t/configurations-lost-while-creating-a-dynamic-node-and-flow/20155)

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**Author:** [@sriramachandramanjun](https://discourse.nodered.org/u/sriramachandramanjun)\
**Replies:** 6\
**Last updated:** [14 January 2020 14:31 UTC](https://discourse.nodered.org/t/configurations-lost-while-creating-a-dynamic-node-and-flow/20155 "2020-01-14T14:31:51Z")

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I have started exploring, how to create a dynamic nodes in NodeRED and I found it was not possible, instead I can create a new flow dynamically with the nodeids mentioned below as suggested by the documentationo. I teste…

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## [Sending HTTP POST Requests](https://discourse.nodered.org/t/sending-http-post-requests/20279)

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**Author:** [@DGRAY325](https://discourse.nodered.org/u/DGRAY325)\
**Replies:** 3\
**Last updated:** [14 January 2020 12:43 UTC](https://discourse.nodered.org/t/sending-http-post-requests/20279 "2020-01-14T12:43:18Z")

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I have a software that offers a REST API with a ton of tools to test and implement custom integrations. I'm new to all this and hoping someone could guide me in the right direction. I setup a basic flow using an inject, …

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## [Help to build a JSON packet](https://discourse.nodered.org/t/help-to-build-a-json-packet/20288)

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**Author:** [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)\
**Replies:** 4\
**Last updated:** [14 January 2020 04:51 UTC](https://discourse.nodered.org/t/help-to-build-a-json-packet/20288 "2020-01-14T04:51:10Z")

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(Yes, I'm probably a gluten for punishment.) I'm messing around with sending a message over MQTT and need extra things in the message. The basic system works, but when I try to add extra stuff on the message, it all fa…

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## [Node-red-contrib-fs not finding /dev/ttyUSB0](https://discourse.nodered.org/t/node-red-contrib-fs-not-finding-dev-ttyusb0/20262)

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**Author:** [@Colin](https://discourse.nodered.org/u/Colin)\
**Replies:** 10\
**Last updated:** [13 January 2020 21:27 UTC](https://discourse.nodered.org/t/node-red-contrib-fs-not-finding-dev-ttyusb0/20262 "2020-01-13T21:27:01Z")

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On a Pi (Zero) running Raspbian Buster when I do ls /dev/tty\* I see lots of entries, including ttyUSB0, provided something appropriate is plugged in. However, when I try to find that with node-red-contrib-fs it does n…

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## [Msg topic explanation](https://discourse.nodered.org/t/msg-topic-explanation/20280)

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**Author:** [@scottriggle](https://discourse.nodered.org/u/scottriggle)\
**Replies:** 2\
**Last updated:** [13 January 2020 20:41 UTC](https://discourse.nodered.org/t/msg-topic-explanation/20280 "2020-01-13T20:41:29Z")

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I've just started Node-Red and I've been taking lots of tutorials and they all mention msg.topic but never explain what it is used for.

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## [Flows stopped due to... ui\_base](https://discourse.nodered.org/t/flows-stopped-due-to-ui-base/20265)

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**Author:** [@Andres](https://discourse.nodered.org/u/Andres)\
**Replies:** 6\
**Last updated:** [13 January 2020 20:00 UTC](https://discourse.nodered.org/t/flows-stopped-due-to-ui-base/20265 "2020-01-13T20:00:08Z")

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Hello everyone, i have this error from nr and i can't get it to work, what does it means and how can i solve it? Flows stopped due to missing node types. ui\_base i've tryed this but when i reintall nr it keeps showin…

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## [Setup SSL within Postgresql-variable configuration node doubt](https://discourse.nodered.org/t/setup-ssl-within-postgresql-variable-configuration-node-doubt/20267)

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**Author:** [@lenny1972](https://discourse.nodered.org/u/lenny1972)\
**Replies:** 0\
**Last updated:** [13 January 2020 16:28 UTC](https://discourse.nodered.org/t/setup-ssl-within-postgresql-variable-configuration-node-doubt/20267 "2020-01-13T16:28:12Z")

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Having to secure the Node-Red / PostgreSQL DB connection from sniffing I'm wondering if it will be sufficient - after configuring in the Postgres configuration file "SSL" option to "ON" and specifying the correct path (a…

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## [Before re-deploy i want to clear global variable](https://discourse.nodered.org/t/before-re-deploy-i-want-to-clear-global-variable/20247)

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**Author:** [@kiran](https://discourse.nodered.org/u/kiran)\
**Replies:** 3\
**Last updated:** [13 January 2020 15:49 UTC](https://discourse.nodered.org/t/before-re-deploy-i-want-to-clear-global-variable/20247 "2020-01-13T15:49:16Z")

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Before re-deploy i want to clear global variable content how to do that ?

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## [Docker: Listen on port 80](https://discourse.nodered.org/t/docker-listen-on-port-80/17940)

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**Author:** [@techtimo](https://discourse.nodered.org/u/techtimo)\
**Replies:** 1\
**Last updated:** [13 January 2020 15:36 UTC](https://discourse.nodered.org/t/docker-listen-on-port-80/17940 "2020-01-13T15:36:39Z")

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Hi there, I'm using the stock NodeRed docker image and I need it to listen to port 80. The container is running on Azure container instance. On my localhost I could simply run docker run -d -p 80:8080 nodered to map t…

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## [Update 'project' from a flow](https://discourse.nodered.org/t/update-project-from-a-flow/19908)

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**Author:** [@pax](https://discourse.nodered.org/u/pax)\
**Replies:** 2\
**Last updated:** [13 January 2020 11:42 UTC](https://discourse.nodered.org/t/update-project-from-a-flow/19908 "2020-01-13T11:42:57Z")

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Is there to have a flow initiate a git pull and thus update itself?

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## [Node red error wont load](https://discourse.nodered.org/t/node-red-error-wont-load/20253)

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**Author:** [@mjdula](https://discourse.nodered.org/u/mjdula)\
**Replies:** 2\
**Last updated:** [13 January 2020 10:43 UTC](https://discourse.nodered.org/t/node-red-error-wont-load/20253 "2020-01-13T10:43:27Z")

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I attempted to connect to my pi to do an update. I can VNC connect to the pi but when I attempt to run node red I receive this: internal/modules/cjs/loader.js:638 throw err; ^ Error: Cannot find module '/home/pi/red' …

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## [How to access global variable in HTML file of custom node](https://discourse.nodered.org/t/how-to-access-global-variable-in-html-file-of-custom-node/20248)

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**Author:** [@kiran](https://discourse.nodered.org/u/kiran)\
**Replies:** 1\
**Last updated:** [13 January 2020 10:14 UTC](https://discourse.nodered.org/t/how-to-access-global-variable-in-html-file-of-custom-node/20248 "2020-01-13T10:14:40Z")

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first node (name connection)- \>\> in connection node - i accept device info like ip address and all details about device. second node -( name request) -\>\> In request node i want to create drop down list of ip address whi…

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## [Postgres Node causing issues](https://discourse.nodered.org/t/postgres-node-causing-issues/20196)

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**Author:** [@lesterkelly](https://discourse.nodered.org/u/lesterkelly)\
**Replies:** 4\
**Last updated:** [13 January 2020 08:59 UTC](https://discourse.nodered.org/t/postgres-node-causing-issues/20196 "2020-01-13T08:59:27Z")

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Hi, I'm seeing a very strange issue while using "node-red-contrib-postgres-variable". For some reason when I use this node I can't set a flow constant in one branch and get the flow constant in a different branch. I c…

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## [Temperature Control MAX31865, Arduino, Rpi](https://discourse.nodered.org/t/temperature-control-max31865-arduino-rpi/20241)

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**Author:** [@Alden](https://discourse.nodered.org/u/Alden)\
**Replies:** 0\
**Last updated:** [13 January 2020 04:23 UTC](https://discourse.nodered.org/t/temperature-control-max31865-arduino-rpi/20241 "2020-01-13T04:23:55Z")

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I have a two functions that successfully read the temperature from a MAX31865 serial connection via Arduino and sends out a 0 or 1 if it is above or below the max temp I set within the function. I will use this message …

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## [Something has really messed up on one of my machines](https://discourse.nodered.org/t/something-has-really-messed-up-on-one-of-my-machines/20178)

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**Author:** [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)\
**Replies:** 4\
**Last updated:** [12 January 2020 11:51 UTC](https://discourse.nodered.org/t/something-has-really-messed-up-on-one-of-my-machines/20178 "2020-01-12T11:51:31Z")

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Ok, I have made mistakes, but to the best of my knowledge, all those stupid ones have been put to rest and things are good. I have as a main machine a NUC and I test flows on it and when they work I export the flows to …

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## [How to copy my Flows - From Pi to win10?](https://discourse.nodered.org/t/how-to-copy-my-flows-from-pi-to-win10/20195)

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**Author:** [@lost66](https://discourse.nodered.org/u/lost66)\
**Replies:** 6\
**Last updated:** [12 January 2020 09:27 UTC](https://discourse.nodered.org/t/how-to-copy-my-flows-from-pi-to-win10/20195 "2020-01-12T09:27:51Z")

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hi guys, so i made quite an complex flow on my pi some time ago, but since then something went wrong with the pi / usb stick. i want to continue with the flow so i decided to install nr on my laptop, i also managed t…

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## [Raspberry Pi GPIO - email](https://discourse.nodered.org/t/raspberry-pi-gpio-email/20207)

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**Author:** [@Guynouk](https://discourse.nodered.org/u/Guynouk)\
**Replies:** 3\
**Last updated:** [12 January 2020 08:40 UTC](https://discourse.nodered.org/t/raspberry-pi-gpio-email/20207 "2020-01-12T08:40:41Z")

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Just got my Raspberry Pi set up. Now trying to create my first flow. Have managed to successfully generate/send emails when an input pin (GPIO3) changes state but I've got a couple of problems I'm struggling to resolve. …

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## [How to install and use "node-red-contrib-mcp23017"](https://discourse.nodered.org/t/how-to-install-and-use-node-red-contrib-mcp23017/5930)

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**Author:** [@Andre](https://discourse.nodered.org/u/Andre)\
**Replies:** 13\
**Last updated:** [12 January 2020 05:19 UTC](https://discourse.nodered.org/t/how-to-install-and-use-node-red-contrib-mcp23017/5930 "2020-01-12T05:19:00Z")

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Hello everyone, I would like to know how to install the node-red-contrib-mcp23017 node node-red-contrib-mcp23017 (node) - Node-RED but I only get error messages when I try to install it. I don't understand how to i…

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## [Mustache notation not working in Call Service Node](https://discourse.nodered.org/t/mustache-notation-not-working-in-call-service-node/20206)

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**Author:** [@nineclicks](https://discourse.nodered.org/u/nineclicks)\
**Replies:** 2\
**Last updated:** [12 January 2020 01:10 UTC](https://discourse.nodered.org/t/mustache-notation-not-working-in-call-service-node/20206 "2020-01-12T01:10:43Z")

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I have a function feeding in to a Call Service Node. This is the function code: let state = context.get("door\_state"); if (state === undefined) { state = 0; } state ^= 1; context.set("door\_state", state); msg.servic…

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## [Setting up Webhook connection between 2 servers](https://discourse.nodered.org/t/setting-up-webhook-connection-between-2-servers/20192)

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**Author:** [@Paul-Reed](https://discourse.nodered.org/u/Paul-Reed)\
**Replies:** 10\
**Last updated:** [11 January 2020 22:34 UTC](https://discourse.nodered.org/t/setting-up-webhook-connection-between-2-servers/20192 "2020-01-11T22:34:40Z")

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I have previously used node-red-contrib-webhookrelay which is really easy to set up and use, although it is a 'paid for' service if you make more than 150 webhook calls per month. Another forum post inspired me to try a…

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## [Sporadic measeruments to timeseries db in a regular interval](https://discourse.nodered.org/t/sporadic-measeruments-to-timeseries-db-in-a-regular-interval/20075)

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**Author:** [@ssahlender](https://discourse.nodered.org/u/ssahlender)\
**Replies:** 18\
**Last updated:** [11 January 2020 21:21 UTC](https://discourse.nodered.org/t/sporadic-measeruments-to-timeseries-db-in-a-regular-interval/20075 "2020-01-11T21:21:41Z")

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Hi together, I have some idea to save sporadic measurements in a regular interval to a time series database but I'm not sure if that's the right approach or if there are better ones. Some info: I'm using node-red-cont…

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## [Node-red-node-mysql 0.0.19 "ER\_HANDSHAKE\_ERROR: Bad handshake"](https://discourse.nodered.org/t/node-red-node-mysql-0-0-19-er-handshake-error-bad-handshake/20098)

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**Author:** [@digidax](https://discourse.nodered.org/u/digidax)\
**Replies:** 21\
**Last updated:** [11 January 2020 15:29 UTC](https://discourse.nodered.org/t/node-red-node-mysql-0-0-19-er-handshake-error-bad-handshake/20098 "2020-01-11T15:29:01Z")

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Hi, the endpoint for connecting mysql (v5.x) produces this error: "Error: ER\_HANDSHAKE\_ERROR: Bad handshake". Login from the cli of this CentOS 7 Linux machine to the mysql server is working. What can I do please? Nod…

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## [PID Mixing Valve Temperature control](https://discourse.nodered.org/t/pid-mixing-valve-temperature-control/18316)

<div class="topic-metadata">

**Author:** [@sokomm](https://discourse.nodered.org/u/sokomm)\
**Replies:** 28\
**Last updated:** [11 January 2020 13:20 UTC](https://discourse.nodered.org/t/pid-mixing-valve-temperature-control/18316 "2020-01-11T13:20:06Z")

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Hello I need help controling a mixsing valve so that the output temperature is around 60 C

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## [Calculate a checksum](https://discourse.nodered.org/t/calculate-a-checksum/20142)

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**Author:** [@zamzon](https://discourse.nodered.org/u/zamzon)\
**Replies:** 10\
**Last updated:** [11 January 2020 09:51 UTC](https://discourse.nodered.org/t/calculate-a-checksum/20142 "2020-01-11T09:51:13Z")

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Hi I need to calculate a checksum i a buffer payload the way to calculate the checksum is as follow In Windows, Start / Programs / Accessories / Calculator In Calculator, under View, Select Scientific In Calcu…

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## [Homekit users - which nodes have you installed?](https://discourse.nodered.org/t/homekit-users-which-nodes-have-you-installed/11044)

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**Author:** [@877](https://discourse.nodered.org/u/877)\
**Replies:** 29\
**Last updated:** [11 January 2020 05:43 UTC](https://discourse.nodered.org/t/homekit-users-which-nodes-have-you-installed/11044 "2020-01-11T05:43:42Z")

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I'm using the Homekit bridged node , however there is a known bug which means that node red needs restarting after every deploy (otherwise the Homekit nodes do not work). The developer is working on a fix, which I am gr…

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## [Searching for a node injector with an input](https://discourse.nodered.org/t/searching-for-a-node-injector-with-an-input/20168)

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**Author:** [@pvanklink](https://discourse.nodered.org/u/pvanklink)\
**Replies:** 10\
**Last updated:** [10 January 2020 22:03 UTC](https://discourse.nodered.org/t/searching-for-a-node-injector-with-an-input/20168 "2020-01-10T22:03:24Z")

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I used a injector-node in the passed with an INPUT functionality. I need this to reset my dashboarditems. Is is this node gone or am i looking wrong? Another question is that i use an dashboard list node. i fill this…

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## [MQTT triggering notifications on deploy](https://discourse.nodered.org/t/mqtt-triggering-notifications-on-deploy/20163)

<div class="topic-metadata">

**Author:** [@Mobile\_NR\_Env](https://discourse.nodered.org/u/Mobile_NR_Env)\
**Replies:** 5\
**Last updated:** [10 January 2020 21:32 UTC](https://discourse.nodered.org/t/mqtt-triggering-notifications-on-deploy/20163 "2020-01-10T21:32:42Z")

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I'm sure this must be a simple fix. HA trigger node automatically disconnect then reconnect on deploy of changes in Node Red. Now I've switched to MQTT states for triggers. When I deploy changes on any flow, I'm gettin…

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