Node red set msg topic. payload : number 1006 Would be nice if anyone could point me in the right direction! A place to share nodes and flows, and discuss Node-RED, a low-code tool for event-driven applications. Then set it to send the msg after 2 parts are received, so it waits for both the "time" and "channel" topic msgs to arrive before it "continues" the flow Apr 21, 2025 · Thanks @omrid - just linking to it so that it's easier for future navigation: ‘widget-action’ messages set msg. An easier way for doing this is by using Subflow properties. url to make query with http. Note : constructing a new message object will lose any message properties of the received message. Any ideas??? May 24, 2024 · While the function correctly sends on/off based on input. or is there a better way to do this. The payload comes from the incoming message. Discussion The MQTT Input node must be hardcoded with the topic filter to use - it cannot be changed dynamically. url and msg. Jun 6, 2019 · I am using the excellent node by @gab. Per topic gate The per topic gate is a single switch that can block or pass messages according to their topic Dec 2, 2020 · As you can see above, I have retrieved the set temperature of the climate control and I have subtracted 2 degrees C from this value and placed it into the msg. The node supports setting various JavaScript types as well as some Node-RED specific types. payload =="on") { msg… Feb 23, 2025 · Third party integrationsNode-RED node-red Caesar_Naykid (Caesar) February 23, 2025, 4:25pm 1 Hello, @Biscuit I was wondering if you might help me. retain respectively. This happens also in the generic ui-template node. The split node is one of the core nodes in Node-RED, thus installed by default. Nov 14, 2018 · The function node (and all nodes) only works on one message at once, it holds no "state" about the previous message. Jan 20, 2025 · In the example flow we use two inject nodes to inject a message on two different topics to a function node with two outputs. payload to change its contents to trigger a call service node. channel before the message enters the template node. done() to tell the runtime that the function node is finished and return it without sending a further message. The fix for the function node is: msg. The door and window values are generated by an mqtt in node room/+/therm/set connected to this function parsename = msg. Nov 21, 2024 · The dashboard switch configuration is shown below: The on and off payload are set in the switch and the topic field is used to pass in the switch name to the publish function. As msg. topic or set it to display the 'complete msg object'. Features subscribe dynamically to topics unsubscribe automatically after first msg received unsubscribe dynamically specific node/nodes from topic pass messages through node when msg. This functionality is valuable for automating tasks and efficiently managing communication flow within Node-RED flows. topic. Discussion Ensure the Topic field in the MQTT Output configuration dialog is left blank to use the topic message property. topic = "INSERT INTO ambiente VALUES (null, " + msg. topic is required. Aug 27, 2025 · Version 2. topic value so they can be identified later in the flow. speed, payload. Likewise the QoS and retain values can be configured in the node or, if left blank, set by msg. Nod-RED 提供訊息的變數格式 Node-RED 刪除一個訊息的方式 Node-RED 移動一個訊息的方式 Node-RED 數值相加或等比換算方式 1. mrdvt92 30 April 2021 02:10 3 May 1, 2021 · Here is a function you can use inline (in series) It adds msg. By discarding the original message, a user of your node would have to resort to storing the msg (or it's properties that are important and necessary for downstream nodes) before passing the message through your node, then picking them up again afterwards. "RFX/" & topic The second change pushes the msg down onto the msg. My goal is, to read a flow variable that belongs to the respective sensor. topic="WHATEVER YOU WANT"; pass the message to a matt-out node and it should do what you want May 26, 2021 · Hi, I want to change a msg. request. payload to msg. You can do this is numerous different ways In a function node: msg. What should I write on the function node to pass a message directly to the mqtt out using msg. payload is an array. test: $} But this doesn't work 🙄 I tried a lot of Set Current Target Temperature A simple flow to add the preamble to a Set Current Target Temperature command. It is important to understand The msg object if you want to work with node-red. A Send Raw Bytes node sets the module address and command. How do I properly ID each input within the function? E. This will insert the entity id that triggered the event-state node into msg. topic property. Tips Restart node-red after inserting dongle to ensure it is detected Known Issues Apr 24, 2021 · Hi everyone, it is the first time I am using Node Red and I have a question to you. The function sends the message to the output based on the topic name. , with persistent values after reboot. direction, etc. lastFY. When that change comes in i want to use the msg. dates to the msg object (doesn't alter or change other msg properties like payload) You can access things like msg. topic, the topic set before, is still present. Each message carries data that nodes modify, process, or analyze, so understanding how these messages are structured and handled is crucial. It can also be used to automatically trigger flows at regular intervals. A set of Node-RED enhanced boolean logic and utility nodes, flow interruption, blinker, invert, filter, toggle etc. Message design The messages that pass through a flow are plain JavaScript objects that can have properties set on them. I would like to execute everything in one change node Jun 7, 2022 · Ok then use the payload of the button only as a trigger and then use a change node which constructs the msg object completely new. Aug 26, 2025 · Node red works by passing messages between nodes. 0. 1 Node-red node for limiting message rate per topic npm install node-red-contrib-message-rate-topic node-red-contrib-limit-message-rate-topic Limit the rate of msg with a specific topic to the set period. The Join node has been configured in manual mode to create a key/value object using msg. You will have to use the context to store state between them. When received msg with same topic, timer is reset and previous message is discarded (delivered is last message in topic within timer only). This will break some flows, for example the HTTP In/Response flow requires the msg. Unfortunately, that's not my problem. It also flows to a Change node, with the following configuration: Then, to the switch node: And finally Mar 13, 2019 · Hello ! ! ! I will read the Tobic of an Message. They each set a unique msg. Mar 29, 2020 · Hi, I am reasonable new to node-red. topic as variable name. The bottom flow provides a set of Inject nodes to change the current value of the flow. They usually have a payload property - this is the default property that most nodes will work with. a: ${msg. I have a change node in which I process and set various data from the input. This can be used as a simple gate like function - based on the value of some other input, that you store into the flow. Now configure it to set the property msg. You might have to alter { {payload}} to { {channel}} and put the channel number in msg. For example, you have an MQTT node subscribed to multiple sensors and you want to pass the messages to different Dashboard ui_gauge nodes. May 30, 2024 · So, adding this msg. temperature Aug 26, 2025 · Node red works by passing messages between nodes. The message to send defaults to the timestamp as payload and an empty topic. In the case you have posted a screen shot ofit This Node-RED module provides nodes for setting and getting context variables within your Node-RED flows using msg. This part works fine Then, I know how to use a ‘Call Service’ node to set the temperature with data like {“temperature”:22}; However, I do not know how to insert the msg. Nov 8, 2021 · The msg. So you want to add msg. Compatible also with Homeassistant values. set("{{msg. time is sent to the “change property” node (set to Off label), the colour of the button gets changed to I have a function node that has a few outputs, what is the correct way of setting a different topic for a particular output? ie: return [ {payload:0}, {payload:1} ]; Sets the payloads … Aug 3, 2023 · Can you show us an example message that you are sending to MQTT please. res properties to be preserved end-to-end. If a message with a specific topic is received, it is sent out immediately. Aug 5, 2024 · In the example below, the Join node utilizes manual mode to merge three payload properties into one based on the value of the msg. You can now connect,disconnect,subscribe and unsubscribe dynamically. Simple gate and per topic gate using the switch node This flow demonstrates how to use a switch to create a gate to block or let messages pass. url property. For example, changing what MQTT topic it publishes to. In the default node set, the only node provided is the sentiment node, which can be used to try and determine the sentiment of an incoming message based on the words used in the message, for example, an email or tweet. ? By example. topic object. Which would also be nice, to set Pth = 0, if the compressor is a 0Hz: this could be quite a complicated function Nov 18, 2021 · Hello, I am receiving an array of 16, with values. The switch then checks if flow. topic to the message object. mode [msg. EDIT: If you are using the topic then { { topic }} will give you . I wanted to replace 0 ,1 with some topic name with values received and return in the same array format. For getting values of already set variable, only msg. payload to = 0 if off I get these values: I´ve made a "flow. test message contains a string value: 'product'. Each recipe addresses a specific problem and shows by example how it can be solved using the capabilities of the platform. You should also read the documentation page on context. For more information about messages in Node-RED you should read the Working with messages section of the user guide. payload contains the ping value sadly this doesn't work. topic would be "HA/Presence_response/test". It doesn’t matter what you save it as, as long as you remember to use it in the final stage. end}} here is a demo Sep 7, 2018 · To set other properties, you'll need to add a Change node after the ui_template node. MQTT input node Based on core Node-RED "mqtt in" which uses "mqtt-broker" config node. If you want to transform a message based on a previous message you need to learn to use the context objects to store information. topic and then you reference topic using mustache templates in the call-service node. sorry I'm a beginner Node-red node for delaying message for topic npm install node-red-contrib-delay-topic-message Node-red node delay-topic-message Basic usage Delay message by set seconds. payload from flow variable (you created before) and send the message into the http request node. Usage Set msg. Apr 2, 2020 · node. The topic used can be configured in the node or, if left blank, can be set by msg. I have several sensors in use that provide me with counter data. time_left_home_$ {id},” or maybe some assignment thereof. set msg. send({payload:msg. It is widely used for home automation by many non-professional programmers and runs well on Pi's. Set the debug node to Output Complete Message. send(msg) works OK, but using emit to 'widget-action' overwrites the topic property. Unfortunately, although you can grab the whole msg object using "$" in JSONata, Node-RED will not let you put the msg object into the payload directly as it thinks you are creating a circular object definition. Set msg. payload}; I tried with double and single quotes, $ sign, but could not get it to work Aug 5, 2024 · Change What's the Change node in Node-RED used for? The Change node in Node-RED is used for modifying the content of messages within a flow. state Jan 20, 2025 · In the example flow we use two inject nodes to inject a message on two different topics to a function node with two outputs. enabled to msg. gate that is set using a change node. Flows can also be triggered once right after Node-RED starts the flows or with a delay. topic here. The difference with the MQTT node is that this dynamic node supports topics/channels passed through msg. I have used a call service node with this json: { "data Alternatively, make the payload an object, and inject payload. These message are contained in the message object. Publish messages to a topic Problem You want to publish a message to an MQTT topic on a broker. start}} to {{dates. Using MQTT with Node-RED Node-RED is a free cross-platform programming tool for wiring together hardware, APIs, and online services developed originally by IBM for IOT. analyze is set to false. Sep 20, 2024 · Understanding Node-RED Messages Node-RED relies on passing messages between nodes to build dynamic IoT, automation, and data-processing workflows. The next msg with the same topic will be sent only after the configured Apr 5, 2023 · Analysis nodes Analysis nodes perform standard analyses on incoming messages. topic Two timestamp inject nodes into a function node that acts upon each message/topic uniquely. topic to what ever you want You can configure the debug node to "output" "complete message object" which will display the whole message object to check it has done what you want In this example, the Inject node sets the msg. topic as the key. payload value containing the execution command. gate is true. Feb 21, 2023 · @jw_te_r The gauge node will accept a string as long as it parses to a number You can set the gauge value format field to {{msg. toggle in addition to the msg. payload to the value (0-255). emit('widget-action', this. timestamp #1 topic = 1 timestamp #2 topic=2 Within function: Aug 20, 2025 · Learn how to store data in node-red context,flow and global variables. I want to have the iOS notification setup so I get the video stream from the camera that triggers in the notification. If started with the switch, no topic should be mentionned. topic, but you don’t always need to use an inject node to do this. payload having key Humidity or having key Temperature. In this flow the URL is set to: The message item can be empty too. May 31, 2017 · Put a change node or a another function node between DB2 and the process function node to add/change the topic on the msg. How can you set msg. topic}}", msg. So please no advanced answer please 🙂 Mar 30, 2019 · I need to. How could I, please help. If it contains a binary Buffer the message will be published as-is. . When the Node-RED runtime starts it will substitute the environment variable value into that property of the node. in my project i have a number of settings that are changeable on a dashboard. : msg. payload1 - 20 of 20 1 Dec 5, 2024 · Workaround was to insert a stupid change node in between without obviously changing at all in the message: "set msg. If you look at the writeLogMessage instance, that is in the second exported flow of my first message, I'm trying to inject the value of msg. The message sent by the Inject node can have its payload and topic properties set. qos and msg. Figure 3. This does allow the topic to be changed, although doing so does require a Inject The Inject node can be used to manual trigger a flow by clicking the node’s button within the editor. payload, msg. The Change node can be used to set properties of a message. payload. I am absolutly new in this. Here’s my flow: The alexa-home node flow to switch node works perfectly. The new target temperature is injected with a payload. If you set the topic attributes to a value, the input msg needs to contain the same topic name to execute On/Off resp. as I came across a thread (original post) and saw you seemed to understand well working with payloads from a current state node in This Node-RED module provides nodes for setting and getting context variables within your Node-RED flows using msg. I'm trying to achieve this by using the function node. Node-red-context-monitor: A node to monitor a Node-RED context Steve-Mcl 24 October 2023 15:11 2 This is a node module for node-red that is identical to the default MQTT node. I have tried the change node without luck. Jun 11, 2020 · Embarrassing enough I have no idea how to change a topic on a message. I also recommend that you have a look at the official Node-RED documentation, where messages and variables are covered in detail. I've spent 9 hours Googling and playing with function and change nodes but I can't get it to work as required. My attempts always end with the error message that the function tries to send a message of type string. Node-RED has many plug-in modules written by the community. topic if (msg. payload); return msg; This will create a global variable named room-set with the value received via mqtt. id, msg)), their topic property is getting overrun and becomes undefined. Solution Use the Switch node to check the value of the property against different values corresponding to Sounds like you want a join node (in "manual" mode), set to create a "key/value object" using the msg. However, I am concerned about the performance impact if continuous polling is required. thisMonth. Both service nodes receive input, which causes them to trigger together. $socket. Aug 12, 2020 · node-red-node-sqlite using msg. Feb 13, 2023 · How to set a specific topic to the output of a function node General Flixm 13 February 2023 20:10 1 Sep 5, 2018 · The join node is the correct way to combine the 2 incoming messages. complete or not. topic? Route a message based on one of its properties Problem You want to route a message to different flows according to the value of the msg. split("/")[2] globalname = parsename+"-soll" global. Discussion In the example flow, each Inject node represents a different source of messages. payload so, in this case, the outgoing msg. topic reports "Error: SQLITE_RANGE: column index out of range" when msg. 8. It does not make sense to define a static payload in the MQTT-out node. In general, function nodes should return the message object they were passed having made any changes to its properties. topic so msg. The entry in the node-settings is just a mouse over label for the input, since nodes can only have 1 input it's not that useful, it's more for when nodes have multiple outputs to make it easier to identify which output is which. a} But this is what gets logged: this is a test. Been working for weeks scouring online docs/threads to move from total beginner to maybe intermediate in Node-red. capacityP | number : 2}} which will round the values to 2 decimal places also. topic as the key name. Nod-RED 提供訊息的變數格式 補充說明：Payload 這一個英文專有名詞個人的解釋及說明，在這個環境下，Payload 表示擷取的資訊內容物。 Jul 26, 2022 · Change the debug node and set it to eithor display msg. Is it possible to use this message as the "name:value" pair? I thought the JSONata must be like: payload. G. a into the message parameter: this is a test. As we know there are three separate streams of messages to join, the node has been to configure to send on a Discussion Once you have sent a retained message to a topic, all subscribers will receive that message when they subscribe. The trigger for my flow is eztimer as follows: It then flows to a HueMagic node, which requires a boolean input. … Aug 25, 2020 · I'm pinging a series of devices with the ping node I want to create a message object that contains device:ping_value All the info is in there as msg. Using this. topic dynamically in my flow "Pth": to a) Pth_H b) Pth_WW c) Pth_PC (Heating, Hotwater, passive Cooling) and the msg. Also note that the indicator is set to display the state of the input. Mar 11, 2016 · In which case the mqtt topic can be set by using msg. topic to the DMX channel (1-512) and msg. The variable is set in a function block before the Aug 5, 2024 · Trigger What is the Trigger Node in Node-RED? The Trigger node in Node-RED facilitates the initiation and repetition of messages at customizable intervals, offering precise control over when messages are sent, their recurrence frequency, and optional delays. a:. Im using node-red with Home assistant, and I'm trying to get notifications when my CCTV gets triggered. payload in place of the number (in this case 22) If I add a new "call service" node for a light and connect it to the "function node" it will set a flow variable without having to edit the function every time. payload" However, something unknown changed nevertheless and the uiTable now accepts the messages passed through the change node in the intended way and updates automatically. So, I get the following message, and want to change the topic to "value". 1 of node red now allows some MQTT settings to be set dynamically. variableValue". 7 Adding in a change node to set a new message property. Here's an 'INSERT' example from one of my flows. topic to ‘undefined’ · Issue #1683 · FlowFuse/node-red-dashboard · GitHub node-red-contrib-message-rate-topic 1. start in a function or you can access values in a template like this FY from {{dates. To give the opc-ua server node a value i need to send my value from the MQTT input as "msg. Oct 24, 2023 · The same result can be better achieved by setting up an event listener that monitors changes to the value of a global variable written in the custom function node. like counter(msg. req and msg. {msg. If not found, you can install manually: In your . targetMode]. Nov 30, 2021 · Changing font color by value of msg. Also how to store this data on disk so as to be available on reboot. May 10, 2021 · In this picture I use the word 'product' in the name:value pairs of payload. Solution Use the MQTT Output node to publish messages to a topic. A Node-RED flow works by passing messages between nodes. topic = "what ever you want" return msg; IN a change node: Set msg. payload objects, which all have unique id's Aug 5, 2024 · In Node-RED, flows are message based, but a message can be split in multiple messages if needed using the Split node. modus" but I don´t know how to link the topic of Pth with the topic of "M". You should use the manual mode and configure it to create a key value object something like this. This is in my Function Node var topic = msg. To clear a previously retained topic from the broker, send a blank message to that topic with the retain flag set. Message properties can be set to flow, or global variable values, and many other types, including JSONata expressions. topic seems to be stored in the node but what of you don't want this? But only pushing the topic received by a earlier node in the flow? When using for example a switch with topic = msg. topic for the acknowledgement MQTT node of "HA/Presence_response" plus the incoming msg. data to save to msg. payload,topic:newtopic}); after the loop we use the node. dates. payload to no value/content so there is no output, so it wont trigger both service node. Inject Node Vs Nov 7, 2022 · Hey, i'm building a connection between an MQTT Input and an OPC-UA Server (node-red-contrib-opcua). One pattern for doing that is by setting msg. topic; return topic; Alway comes in Debug Node Function tried to send a message of type string Where ist the Problem ? Greets Malcom Nov 2, 2018 · So if i would make a function node, where I set url + id to msq. The msg. Situation: I receive data from a sensor (counter and topic are relevant for me). topic as the name for the flow variable. But that requires adding a Change node in front of every subflow instance in order to set the desired value. It allows you to add, remove, modify, or set message properties and payload values, making it a fundamental node for data transformation and manipulation. Nov 10, 2024 · But how can I extract the payload value from a specific message (having a specific topic) to use as text for a chart node, which has more than one wire / more than one messages as input? Sep 27, 2019 · Have you thought of using a template node and putting the MySQL query in there? Just remember to set the property to 'msg. node-red folder run: npm i node-red-contrib-udmx then restart the node-red service. My OPC-UA Server debugger tells me the variableValue is missing and it seems i can't figure out how to give this value to the Using msg. so it works, but logically without msg. Message options In this article I will expand on messages and introduce Node-RED variables. test. state context property. The Inject node generates a string URL, and the Change node sets the msg. Example Show flow Nov 21, 2022 · As you will remember, this is the output that fires when msg. payload always has a value. Aug 1, 2021 · How can I name a flow var. topic) Or similar to this example. topic etc in notify-node json. payload as variable value and msg. The following flow works, but when the payload. lau with my node red/Blynk projects. One possible workaround is to set the topic to an environment variable such as $(MY_TOPIC). set(globalname, msg. Hi, I need help: I want to make a conditional that if the first msg is 0 the payload will go out through a specific exit, if it is 1 through another and so on, but I can't do the code. Then direct the 2 outputs of the switch to 2 change nodes that set the topic to what you want. If you’re interested in contributing to the cookbook you are more than welcome. complete set, then you'll need to add a flag in the msg. #670 Apr 29, 2021 · As the topic is the same for both you can simply subscribe to that topic & use a switch to test msg. I have several of Pete Scargills BigTimers running, and thought it would be useful to have the styled buttons display the remaining time, rather than just “Off”. The function node creates the MQTT topic that is used May 21, 2019 · Hello, Is there a way to dynamically set a property in a change node? Something like: set flow. How it works The switch sends the device name using the topic into the publish function node. Simple gate The simple gate uses a flow variable, flow. The messages are simple JavaScript objects that can have any set of properties. topic'. mstate and that way you know it will still be available after the next step which is the outdoor alerts check. 8 Using a change node to add a new message property Node-RED Cookbook This is a collection of recipes for how to use Node-RED to solve many common programming tasks. { } Is it possible to set the name 'product' with the string value of a msg. A function node adds the preamble to the payload. I've already set the broker adress on the mqtt out node. The payload can be set to a variety of different types: a flow or global context property value a String, number, boolean, Buffer Jul 14, 2021 · Hi how do I add the msg. I'm trying to send my data to a broker via mqtt and I want to specify the message in the "function" block. strings: "hello world" numbers: 42 boolean: true / false timestamp: the current time, in milliseconds, since epoch (January 1st, 1970) JSON: a JSON string that will be parsed to its Object Jul 21, 2021 · I hope someone can help me with my problem. topic on every message passed to the subflow. If you want only certain messages from the ui_template node to have msg. node, will it run with every object automatically and I don't have to worry about using for cycles? at the moment my last node, which is sort, outputs 30 msg. topic not set Description Subscribe to topics specyfing msg. create a msg. The problem is that your function node is ignoring the incoming data and creating a new message with just a topic set. Discussion In the example flow, the top flow represents the stream of messages that can be stopped or routed to one of the three outputs by the Switch node. payload sent by the ui_template node which can checked for using a Function node to see if it should set msg. Jun 2, 2021 · I’m having an issue with getting a msg. So instead, we build the payload manually: { "topic": topic, May 29, 2023 · Hello @E1cid, Thanks for the fast response. That way you will see everything in the msg. Any ideas? What did I miss? Best In my custom UI node, when I send messages as 'widget-action' (this. payload I know I can do it in javascript, but it would be better with a change node. Jan 16, 2022 · The change node takes something that already exists and sets it as a new part of the msg object. topic to the payload is failing, and I’m sure it’s because my syntax is bad in “input_datetime. note to “this is not being analyzed” as shown in Fig 3. This sounds like a good application of a Change node, although the new Inject nodes in the more recent versions allow you to inject unlimited and arbitrary msg object elements (this is not the version that ships with the Raspbian OS, so requires an update). Also be aware that the process function node will always receive 2 independent messages, 1 from Q1 and one from DB2. topic contains the device name And msg. i tried many syntaxes and thought to have it working but then not really: flow. 1ck0a usi9shd hg ag le8o7g js66o3 mjtzj qll2z3 gwrj 46ntotu