It may be unrelated, but Windows installed some updates and rebooted my PC last night. When I logged in this morning Node-RED would not start. I keep getting the following error: [image] I have deleted the file in question and installed node-red again, but I keep getting the same error message. …

Can you show us the code you are using to write to the context? Is it possible you are not doing flow.set()?

OMG, I am as thick as two bricks. :flushed: @UnborN pointed that out to me a while back and I confidently said, but it works... I read a variable in. I then update it, and it shows as being updated in the sidebar, but I did not use the flow.set command and I guess that's the problem.... doh!!!! L…

I remember why I did what I did... I couldn't find out how to update just a single property of a variable (using flow.set) without overwriting the whole variable with just one value.... and it updated just fine when I update the variable directly (but obviously that was not the case).... I'll dig ar…

Because the thing you are saving in context is an object, when you do flow.get it gives you a reference (or pointer) to the cache of the object from the file in memory. When you change a property of that object it changes the version in memory so appears to work fine. It is, however, the flow.set(…

@Colin Yeah, I kinda figured that out (the writing to memory vs to disc) when you asked the question about did you use "flow.set". So I am fiddling around again and maybe you know the answer... how would I flow.set my HW_Values flow variable? [{"id":"d2657346.fe2d5","type":"function","z":"f5fbd2b…

Don't overwrite the reference that you get from flow.get() (ie HW_Values), that is not a good idea anyway, it means your code is rather confusing. Use a new variable name on the second line. Then at the end flow.set("hw_values", HW_Values)

I've timed out on this one, have to start preparing for dinner. I can only see complicated ways of reading and updating a variable to presumably then allow me to flow.set the whole variable .... too many lines of code and too much testing, and the big AND, I am updating variables all over the shop…

[image] alex88: I can only see complicated ways of reading and updating a variable to presumably then allow me to flow.set the whole variable What's complicate about const HW_Values = flow.get("hw_values"); const HW_Val = HW_Values.find(HW_Value => HW_Value.de…

But you don't have to get/set the whole of an object when using Node-RED's variables. Here is a quick example: var env = { "args":"--userDir,./data", "automation":"true", "autorestart":"true", "windir":"C:\\WINDOWS", "windowsHide":"true", "_prog":"node" } context.set('env'…

[image] TotallyInformation: But if you want a bit more efficiency, this is the way to go. Are you sure it is more efficient? Does context.set do a clone or just set a reference?

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TotallyInformation 22 November 2020 18:09 61

For variables in memory perhaps but I don't think that is true of file system variables is it?

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Node-red won't start

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