Extra info for property_path

[rdohms]

Added notes to inform users that in case a field is not present in the mapped class, the property_path can be set to false and thus avoiding the exceptions thrown by symfony.

This is useful for example in forms where an extra field is needed, like in registration where the "i agree to these terms" will not be persisted in the underlying user object.

This was discussed here: symfony/symfony#1960 (comment)

[vicb]

Could you also please add symfony/symfony#3182 at the same time ?

[vicb]

You should #1031 before. Sorry I have little time now.

[rdohms]

Not sure what you want me to do, both of those are closed?

[vicb]

Please also doc the property_path use case of the first issue if not solved by the second.

[Tobion]

maybe make it clear that this means that fields in the form but not part of the request will set the property on the object to null
(so simply not rendering the field will not ignore them as some people thought)

[weaverryan]

Thanks Rafael! This is actually an excellent note - in general we will need to do a better job of explaining the purpose of forms from a data perspective.

I've made a few tweaks at sha: 706119c

To @vicb, yes, we overall need to run through a bunch of the core field types and add missing options. It's pretty high on my list.

Thanks!