Persistent states - node red?

Third party integrations Node-RED
1

Can anyone advise me how to store persistent states via node red? Should I be using a database or is there an easier way?

Thank you

2

no database needed. Node-red can store flow and global variables on some folder (in json format – but not meant for you to use the file directly). You can then use nodes and/or function nodes to access them.

Edit /config/node-red/settings.js and add the following:

contextStorage: {
	store: { module: "localfilesystem"},
    default: { module: "memory" }
},

Restart node-red.

Now if you want to store a variable to file using the change node, change context variable to either flow or global and you’ll see the two types of contextStorage you have defined as dropdown options:

6458f681da95858a5b6c060292f706c05f7ba6f1

Hope this helps.

4 Likes
3

That’s is perfect - thank you

4

Do you know if it is possible to store a variable from within the function node and if so could you explain how please?

Thank you again for you help.

5

Yes. Something like:

	flow.set("status", "on");              // the value is stored in memory
	flow.set("status", "on", "default");   // the value is also stored in memory -- same as above
	flow.set("status", "on", "store");     // the value is stored in a file

You can return the variable from the file in a function using this:

    return flow.get("status","store") || "undefined";

Btw, there is a new “Context Data” viewer that shows all the values of all your variables (in memory and file). Not sure which version it came out:

2018-11-01_09-44-13

Hope this helps.

2 Likes
6

Sorry I forgot to say thank you. This worked perfectly. Thank you.

7

You’re welcome.

8

Hi @rsuplido, apologies for resurrecting such an old thread, but, could you post a bit about where in the settings.js file your insert should go? I stuck it in at the bottom, which produced an error that caused node-red to be unable to start at all until I removed it.

Accepting that I am not a clever person at all, should adding this to the bottom have worked, or should it be inserted in a particular section of the settings file?

Pity my simplicity. Thank you.

9

the node-red settings file needs to be valid JSON.

copy/paste your config file here: https://jslint.com/ and see if it throws any errors

10

Check the Version of Node-red - i believe persistent context only come out in 19.1 and above

This is what the END of my settings file looks like

contextStorage: {
default: {
module: “localfilesystem”
},
memoryOnly: {
module: “memory”
}
}

1 Like
11

Don’t add it at the end of the file. Try adding it maybe before this line:

logging: {

1 Like
12

Mine is definitely at the end of the file on my 3 NR instances and after the logging section - no issues

Craig

13

I put mine as well at the end of the file but did online json-syntax check before saving.

All fine

1 Like
14

Spinning up an older thread again since I have the same question but not able to find an answer.

I have the node-red addon in hass, where can I enable context ? How do I access the nod red settings file?

Edit: found it. it is very simple… in the config folder :slight_smile:

1 Like
15

I know this is an old thread, but maybe this will help some other newbies like me. Some things have changed!

The contextStorage: block quoted earlier in this thread does not work, and no data is saved. The current Node-Red context docs have

contextStorage: {
   default: {
       module: "localfilesystem"
   }
}

Which works. The block needs to be inside the outer “{}” and separated from other blocks by a comma. For me the data is stored in files under /root/addon_configs/a0d7b954_nodered/context, but your path will probably differ.

After restarting with the changed settings.js variables can be set with a Change node as mentioned above or in a function node with code like:

global.set('jsr_global_test', 12.345);
global.set('jsr_global_test_store', 12.345, "store");
flow.set('jsr_flow_test', 12.345);
flow.set('jsr_flow_test_store', 12.345, "store");

And probably in other ways. I don’t see any difference using the optional “store” argument.

After restarting Node-Red a refresh of the Context Data sections shows both the global and flow variables if you are in the same flow that set them. In other flows you will see just the globals, as expected.