muzich/vendor/friendsofsymfony/user-bundle/FOS/UserBundle/Resources/doc/canonicalizer.md

FOSUserBundle Canonicalization

FOSUserBundle stores canonicalized versions of the username and the email which are used when querying and checking for uniqueness. The default implementation simply makes them case-insensitive to avoid having users whose username only differs because of the case. It uses mb_convert_case() to achieve this result.

Warning:

If you do not have the mbstring extension installed you will need to define your own canonicalizer.

Replacing the canonicalizers

If you want to change the way the caconical fields are populated, simply create a class implementing FOS\UserBundle\Util\CanonicalizerInterface and register it as a service:

# app/config/config.yml
services:
    my_canonicalizer:
        class: Acme\UserBundle\Util\CustomCanonicalizer
        public: false

You can now configure FOSUserBundle to use your own implementation:

# app/config/config.yml
fos_user:
    # ...
    service:
        email_canonicalizer:    my_canonicalizer
        username_canonicalizer: my_canonicalizer

You can of course use different services for each field if you don't want to use the same logic.

Note:

The default implementation has the id fos_user.util.canonicalizer.default.