undocumented behaviour: HeadersRegexp wraps regexp in wildcard by default

[bluehallu]

Not sure if this is intended, but using this regexp abc, actually means you're using .*abc.*. I don't think this is appropriate since it doesn't let me specify I want certain order on the Accept header, for instance.

[themihai]

I find this kind of behaviour/regex flavour quite disturbing especially because it's not documented. For example using signin.api{_:(^$|^\.sandbox$)}.example.co.uk with the standard regexp package matches sigin.api.example.co.uk and signin.api.sandbox.example.co.uk but on route.Host that doesn't happen.

[elithrar]

@themihai If you can submit a PR documenting this it'd be hugely appreciated. I don't think we can (safely) change this behaviour given applications depending on it in the wild.

[bluehallu]

@elithrar The problem is that it's not just undocumented behaviour, it's actually preventing you from supplying your own raw regex!

[elithrar]

@bluehallu I get that: but changing it would impact other applications out there. I'm not defending code I wrote (I didn't write it), I'm just making sure we don't make breaking changes where we can avoid that.

[bluehallu]

What about an optional flag to change this behaviour?

[elithrar]

I'm open to that, if you have a proposal?
On Mon, Jun 20, 2016 at 3:42 AM bluehallu [email protected] wrote:

What about an optional flag to change this behaviour?

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[bluehallu]

I'm afraid I only used Go once in my life, spotted this weird behaviour in one of the main libraries and reported it, but that's where my Mux knowledge ends. I don't think I'm in a position to make recommendations about how the Api for this library should be designed in any more detail than I already have. An optional boolean parameter "strict" comes to mind though :)

[themihai]

I think a method StrictRegex on type Router[0] would work best. It would be in line with StrictSlash[1]. What do you think?

[0]

// StrictRegex defines the behaviour of HeadersRegexp, Host and regular expressions
// within the route paths. The initial value is false which means it wraps regexp 
// in wildcard by default.
func (r *Router) StrictRegex(value bool) *Router

[1] https://godoc.org/github.com/gorilla/mux#Router.StrictSlash

[elithrar]

@themihai That would be great.

[mtso]

I'd like to add two examples to the documentation for Route.HeadersRegexp. I'm thinking of adding a new file named example_route_test.go using this article as a guide: https://blog.golang.org/examples.

The example file would contain two runnable examples:

1. func ExampleRoute_HeadersRegexp() for the general behavior where the given pattern matches any substring of the header value.
2. func ExampleRoute_HeadersRegexp_exactMatch() to show how to do a strict pattern that does an exact match with ^pattern$.

[kisielk]

@mtso go for it!

[stale]

This issue has been automatically marked as stale because it hasn't seen a recent update. It'll be automatically closed in a few days.