[Dbix-class] Could not load Schema Class (Billing::Schema). DBIx::Class::ResultSource::add_relationship(): Malformed relationship condition value '': must be prefixed with 'self.'

[Александр Поволоцкий]

Hello

I'm trying to make left join with extra condition

agreements a left join bill_mails bm  on a.id = bm.agreement and bm.bill 
is null

However,

                       { "foreign.agreement" => "self.id",
                         "foreign.bill" => undef
                       },

yields error

  Could not load Schema Class (Billing::Schema). 
DBIx::Class::ResultSource::add_relationship(): Malformed relationship 
condition value '': must be prefixed with 'self.'

Is it possible to make such a clause without extra view?

---

Alex