Hello everyone! I'm a newbee at Node-Red and I'd like to collect information from my MQTT and push it to my database. Initially I subscribe for a branch of topics (Devices/+) and receive around 50 MQTT messages. Now I'd like to combine them into one single object and store it into database at once…

And fianlly it looks like this: [image] With code similar to this: switch (msg.topic){ case 'Dacha/pressure': lLocation="Dacha"; lArea="Pantry"; lMeasurement="Pressure" msg.valid=true; break; case 'Dacha/temp': lLocation="Dacha"; lA…

Another way (instead of the join) is to write a function that stores into one object (with the topic as the key) then store the object in flow. That way it's much easier to inspect in context browser side bar.

[image] Steve-Mcl: Another way (instead of the join) is to write a function that stores into one object (with the topic as the key) then store the object in flow. Do you mean store into an array at Flow level variable? [image] Steve-Mcl: See this article in the cookbook for an example o…

for storing it in one object, i do this... MQTT (topic/subtopic/#) --> function node var val = msg.payload; // get the value var key = msg.topic; //get the topic var mqttData= flow.get("mqttData") || {}; //get the store object mqttData[key] = val; …

[image] SuperBoss9: Looking to this option but can't understand it completely. It seems that I have to add a function that will modify MQTT msg into a way it can be received by Join. The join is really simple. Give it a go.

If you're doing it in a function node - just use local context - no need to expose it to the flow.

[image] dceejay: If you're doing it in a function node - just use local context The assumption is he needs to retrieve it elsewhere for sending to database (although he could make the function multi purpose - i.e. return the store object mqttData out after each update)

The assumption I used was ... [image] SuperBoss9: Is there a handsome way (without Flow variables) to do so?

Absolutely but sometimes its the right thing to do :slight_smile: however (another assumption) i suspect the OP thought he'd have to do 50 change nodes (hence wanting to avoid context) Far too many assumptions

The ideal situation is to subscribe to all topics and push all of them into one query. Now I have something like this that processes each topic separately and put it into DB one by one: [1] And if I subscribe all the topics then I receive them also as separate objects: [2] I saw also an examp…

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Combine several messages from MQTT into one request to DataBase

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Steve-Mcl 6 June 2020 20:26 2

Indeed

See this article in the cookbook for an example of how to join messages into one object.

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Combine several messages from MQTT into one request to DataBase

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