Setting config node attribs from flow?

[Torsten Schmale]

Hi,

I am looking for a way to overwrite config node attribs from within a flow.

Why?

Because I have the mongodb parameters in the settings.js and I now need to set/overwrite the mongodb config attribs on NR startup

thanks in advance

Torsten

[Julian Knight]

If you only need something at startup, then setting in settings.js is best. Either as an environment variable or a global depending on need. Many (all?) nodes can consume an environment variable in a setting by using "{env-var-name}".

[Dave C-J]

To use an environment variable in a node's config you need $(env-var-name) syntax.

[Zenofmud]

For environment variables, here is a writeup I did a couple months ago: https://flows.nodered.org/flow/8a13d11dfe80e279df83341e3e17bcc1

On Feb 26, 2018, at 5:50 PM, Dave C-J <dce...@gmail.com> wrote:

To use an environment variable in a node's config you need $(env-var-name) syntax.

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[Torsten Schmale]

yes, using setting.js is good and the docs tell me how to read these values in a function node.

but the docs don't tell anything about how one can set/overwrite the attributes of a config node.

in other words:

some nodes like mongodb or mqtt do work with central config nodes for host, port, user etc. 

its easy to set them via node-red admin UI but I want to set/overwrite them either on node-red startup or at runtime from within a flow (with my ones I have added to settings.js in the functionGlobalContext

I am wondering that this is not a well known pattern in node-red. Separation of productive credentials from code (or here flows) is always a good idea and necessary if you develop in one environment and then deploy it to a productive environement.

[Torsten Schmale]

Thanks Paul. I have tried that but it does not work (or I understand your writeup wrong):

I have added your statement but on node-start it says: Error: Cannot find module 'env'

I have also tried without and used $(harry) for the database name in the mongodb config node

there it says - "MongoError: database names cannot contain the character '$'"

[Zenofmud]

I’ll review it tomorrow morning (east coast USA)

Sent from my iPad

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[Zenofmud]

Blast, I forgot to correct that (sigh) instead of 

env:require(‘env’)

it should be:

       env: process(‘env’)

and make sure the single quotes are the tick marks not the fancy single quotes.

(off to fix the git)

Paul

[Zenofmud]

(turns out I had fixed it in GitHub gist, but I had made it a secret gist (oops). It should flow over to the node red flows soon but you can go to the GitHub link to see the change.

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[Torsten Schmale]

Thanks Paul, Dave and Julian. I finally got what I want - its working now.

The only remaining restriction is, that the $(env-var-name) does read from env only, i.e. there is no fallback || ... in setting.js possible 

as it is works from within a function node e.g. msg.payload.dbname = global.get('DBNAME');

Finally, my relevant settings.js part and how it looks then in a mongodb config node: