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skydiablo opened this issue May 26, 2013 · 8 comments
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[Routing] backreferences in requirements regex #8139

skydiablo opened this issue May 26, 2013 · 8 comments
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@skydiablo
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query parameter requirements regex:

/**
 * @Route(
 *      "/search/{mac}", 
 *      name="MediaAccessControlVendorLookupSearch",
 *      requirements={"mac" = "(?:[[:xdigit:]]{2}([-:]))(?:[[:xdigit:]]{2}\2){4}[[:xdigit:]]{2}"}
 * )
 */
public function searchAction($mac) {
  ...
}

this will end in this exception

An exception has been thrown during the rendering of a template ("Warning: preg_match(): Compilation failed: reference to non-existent subpattern at offset 66...

thats right, but i have to use the referenz "\2", the routeMatcher need this behaivor

if (0 === strpos($pathinfo, '/vendorLookup/search') && preg_match('#^/vendorLookup/search/(?P<mac>(?:[[:xdigit:]]{2}([-:]))(?:[[:xdigit:]]{2}\\2){4}[[:xdigit:]]{2})$#s', $pathinfo, $matches)) {

so what is to do ?
@sstok
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sstok commented Jun 1, 2013

As the first matching group is named, I guess the second one just starts with 1 not 2.

@lazyhammer
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Looks like valid regex. What's your PCRE version, @skydiablo?

@skydiablo
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PCRE Library Version => 8.12 2011-01-15

@Tobion
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Tobion commented Jun 1, 2013

I found out why this doesn't work. The problem doesn't lie in the route matching, but in the URL generation.
In dev environment the params are checked against their requirements when generating a url. But it uses a slightly different regex (without (?P<mac>. This results in \2 not beeing available (it is \1 instead).
I also found a way to fix this. Will make a PR.

@skydiablo in the meantime you can set strict_requirements: null in config_dev.yml which will prevent this false check.

@Tobion
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Tobion commented Jun 1, 2013

Thinking in more general terms, I come to the conslusion that supporting backreferences is impossible in the requirements check for URL generation. This is because the backreference is global for the whole regex but this check only tests against the single requirement.
So e.g. if your pattern was like "/{otherparam}/{mac}" then the backreferences would be totally different again. So I can fix your specific case where there is no other param before your mac with backrefences. But it's not possible to fix in general.

What might be possible is to use named backreferences instead. Then the position does not shift and it would work both for matching and generating urls.

@skydiablo
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works great:

/**
 * @Route(
 *      "/search/{mac}", 
 *      name="MediaAccessControlVendorLookupSearch",
 *      requirements={"mac" = "(?:[[:xdigit:]]{2}(?P<macDelimiter>[-:]))(?:[[:xdigit:]]{2}(?P=macDelimiter)){4}[[:xdigit:]]{2}"}
 * )
 */

thx !

@Tobion
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Tobion commented Jun 1, 2013

You are welcome.

You can also use relative references which is maybe more appropriate: (?:[[:xdigit:]]{2}([-:]))(?:[[:xdigit:]]{2}\g{-1}){4}[[:xdigit:]]{2}. Otherwise macDelimiter would be returned as a parameter (and set in the request params). It could have unwated sideeffects, e.g. when you use these params to generate a URL again.

@Tobion
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Tobion commented Jun 1, 2013

I renamed the title, so people could find this issue if they have similar problem.

@Tobion Tobion mentioned this issue Dec 16, 2014
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