PSA: Express v5 incompatibility

[bazineta]

Runtime

node.js

Runtime version

Any

Module version

Any

Used with

Express v5

Any other relevant information

Mix of a public service announcement and a question regarding Express v5 compatibility.

There are seemingly innumerable documents published about how to do exciting things like validate Express' req.query using Joi, which in Express v4, works a treat.

Hoping to avoid others running into what I ran into this morning, req.query is immutable in Express v5, which effectively kills the usual approaches; curious if anyone's come up with a clever compatibility solution for this, as at this point, I can describe several promising approaches that don't work.

How can we help?

const foo = schema.validate(req.query);

TypeError: Cannot set property query of #<IncomingMessage> which has only a getter

[Marsup]

I'm not sure how Joi would even attempt to re-assign req.query with this pattern, it doesn't have access to the request with this.

[bazineta]

@Marsup Yes, you're absolutely correct; confused by my own debugging. Large project, lots of validation, apparently inadequate caffeination....

It's this pattern:

const foo = schema.validate(req);

And in such cases, we're usually validating both params and query, and it's the getter-only setup for query that's triggering the exception.

[bazineta]

Per this issue: #2140

You should never try to validate the node request object. You should instead create a new object with a copy of the keys you want to validate like { params: request.params } and validate that.

And that does indeed seem to work fine; apparently we've just been doing it wrong without issues in Express v4 all this time. Leaving this open for the moment, as with the recent release of v5, bound to be other uninformed / unenlightened individuals that'll walk this path (at least I hope so, it'd be comforting to learn that I'm not the only one confused here), and perhaps this will be helpful as more make the jump.

[Marsup]

So no action required here I guess?

[bazineta]

So no action required here I guess?

@Marsup No action required; the new object creation advice from the referenced issue eliminates the issue.

I think a search by someone else having the problem will result in a hit here, and hopefully help them out.