I'm quite new to Node Red but know enough Javascript to be dangerous! I'm primarily an Assembler mainframe guy so this is quite different for me. I'm writing a fairly simple app that requires some initial defaults to be established then allow the user to override those defaults. I want to save th…

Thanks for the advice. Much appreciated. I am going to be using MQTT in my app but I have ruled it out for actually saving data as in my use case above. Having used MQ Series back in the day, I would not want to retain data within it. I have this notion that data belongs in a file! I think that …

Hi @davej , welcome to the forum. Context is a core component of the Node-RED runtime. It is entirely suited for storing values/state that you want saved across restarts. Yes there are alternative approaches possible, (MQTT, databases etc), and some will suggest you go down that route. But there's n…

[image] davej: If you minimize or don't use it - how do you pass data between unwired nodes? You don't. You wire them up, commonly using the Join node where you need to merge data from multiple sources. The persistent context (over restart) question is different, however, as you need someho…

An example of changing the file store flush period to every 5 minutes, if it helps... contextStorage: { default: { module: "localfilesystem", config: { flushInterval: 300 } }, memoryOnly: { module: "memory" } },

Yes thanks. I have that! As I couldn't find it in the doc, I was mainly concerned that it was flushing regardless of the data having changed but that has been confirmed to not be the case.

Here is something I wrote back in 2018 which you might find useful [image] A guide to understanding 'Persistent Context' General This is something I wrote up after playing with the context options. I've filed a PR with some of this added to the Node-RED documentation but t…

Thanks for the link. I had actually come across that whilst searching on the feature a day or two back! Nice write-up!

if no-one minds I'd like to mark Paul's answer as the solution and move this into the FAQ category. OK ?

I have made changes to use Context and found that if I use flow.set("keyx","abc","storeInFile") that I have to then use flow.get("keyx","storeInFile") to get it back. Otherwise if I simply use flow.get("keyx") I get undefined. I would have assumed the variable was already in memory and not have t…

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Saving context - advice requested!

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zenofmud 4 July 2020 09:55 7

Here is something I wrote back in 2018 which you might find useful

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Custom Node: reoccurring processing, context storage, Developing Nodes	9	989	3 January 2021
How do I set flow variables to preserve their value over a restart? General	7	740	9 December 2022
Best method or implementation for storage context between stop and start of node red? General	7	538	16 September 2020
contextStorage questions General	11	2306	12 August 2019
A guide to understanding 'Persistent Context' General	90	45673	31 August 2022

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Saving context - advice requested!

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