do you mean you have nextjs frontend on vercel and express on a separate server?

No

I do nextapp.prepare() then attach that to express on / using server.use

Maybe this is what i need

not 100% sure, not something i've done before

usually servers use APIs to chat to eachother

yes it does

so I can?

testing with this code:

nextjs should not have to set that variable

🤔 maybe if i use global?

have you called dotenv/config on the server

I'm not talking about environment variables

though

I'm talking about runtime variables

oh mybad, i thought you were talking about env

i wasn't aware variables can be passed between applications like that

is it even possible?

that's what i'm trying to figure out

so it looks like next and node have different global contexts entirely even if next is started from within express

if in doubt

ask chatgpt

its usually not too bad at giving somewhat reliable advice.

worst case scenario, I can just fetch from getServerSideProps

the api fetching to and from is the same process, same PID

a bit inefficient

or ditch ssr

OK i know what to do lmao

downgrading to next 13.2.4 just fixed a very weird af bug

I was setting res.locals in express before passing to the nextApp handler, but ctx.res.locals showed up as undefined in getServerSide props. Downgrading fixed it.

success!

put everything you want to maintain reference wise between nextjs and express in res.locals, and call it in next using ctx.res.locals[variable]

nice

so yeah you just passing it in the req/res right?

Yes

Hey @Ring-necked Duck , I hope you don't mind me asking this here. Almost the same problem, but I am instead struggling with env variables
How can I use custom express js in next.js(as you did, with next.prepare() ) and succeed in reading environment variables from the same place? I came across the .env.local thingy, it miserably fails.

I think the solution achieved was to pass values using request body

You can’t share variables in that sense between express js and nextjs. They are different applications with separate contexts.

The documents tend to claim a different thing. Check out the environment variables - section in their documentation (Next.js 's)

However I am not able to achieve the desired outcome

Yes but wasn't it a different subject? The OP wanted to achive sharing I believe not env but run time variables... correct me if I am wrong

Correct.

OP wanted to use variables from nextjs on express

https://nextjs-forum.com/post/1192499141855694940#message-1192508343210758245 looks like solution here

So maybe in next serverisde req.locals is accessible?