Express: Dollar sign not recognized in URL

[jukkasi]

Using ExpressJS 4 I'm not able to get a dollar sign to work in URL e.g.

app.post('/foo/$bar', handler);

Cannot POST /foo/$bar

According to RFC dollar sign should be safe character, is it something I'm missing here?

[Twipped]

Express urls get converted to regular expressions, and the dollar sign is significant in regexp. You could explicitly pass in a RegExp that has an escaped dollar sign.

[dougwilson]

In the version of path-to-regexp that Express is using (not sure if this is an issue in the latest version), it looks like the $ is getting inserted into the constructed regular expression literally in the above mentioned case, i.e.:

$ node -pe 'require("path-to-regexp")("/foo/$bar")'
/^\/foo\/$bar\/?$/i

This may be something we can fix in the 0.x line of path-to-regexp, or confirm if this should work/is it is fxed in 1.x. /cc @blakeembrey

[blakeembrey]

Definitely fixed in 1.x, all literals are escaped. In 0.x, it _may_ be possible to escape but we need to be careful not to break existing usages. For example, in the 0.x branch you could do /([\$]) and escaping that directly is a breaking change as you'd result in two backslashes. So it might need to check for existing backslashes before the literal. I feel like the only issue fixing it on 0.x is ambiguous backslashes, would need to think about it for a little bit.

[mikhailrojo]

Just for someone who stump into this problem
For me helped for the situation when I needed to get www.odata.com/$metadata worked out:

router.get('/([\$])metadata', function(req, res, next){

})

[dougwilson]

@hacksparrow do you think we can document this on the API site?

[hacksparrow]

@dougwilson sure, will add it.

[hacksparrow]

@blakeembrey is enclosing with () mandatory? Simply enclosing the escaped $ within [] works just fine.

[blakeembrey]

@hacksparrow Nope, not in 0.x. In 1.x, it is, because there's too many obscure issues otherwise with parsing. However, in the current version Express.js uses it's basically a valid regexp already with minor transformations on the (, ), / and : characters to give meaning. So even just doing /foo\\$ should work.

[hacksparrow]

Documented in https://github.com/expressjs/expressjs.com/commit/73147d61daf628ddf627b71450c81841c8d3c9c4