Bernhard Graf wrote:
I have just learned, that the JOIN syntax was improved recently, so it
is possible to specify more than just the equality of column values, as
shown in the example from DBIx::Class::Relationship::Base:
My::Schema::Artist->has_many(
cds_80s => 'My::Schema::CD',
sub {
my $args = shift;
return {
"$args->{foreign_alias}.artist" => { -ident =>
"$args->{self_alias}.artistid" },
"$args->{foreign_alias}.year" => { '>', "1979", '<', "1990" },
};
}
);
...
$artist_rs->search_related('cds_80s')->next;
The example above still requires the bind values to be defined
statically in the schema. I couldn't find any examples, about how to
specify bind values at execution time - e.g. likes this:
My::Schema::Artist->has_many(
cds_era => 'My::Schema::CD',
sub {
my $args = shift;
return {
"$args->{foreign_alias}.artist" => { -ident =>
"$args->{self_alias}.artistid" },
"$args->{foreign_alias}.year" => { '>', \'?', '<', \'?' },
};
}
);
...
$artist_rs->search_related('cds_era', {}, {bind => ['1979', '1990'])->next;
This would be an extremely limtied interface, given that you may have
several unrelated complex join-conds, and a view in the FROM on top of
that. How would you theb know in what order would you specify the binds
in?
Isn't something like this possible?
It is possible, but is not yet particularly pretty. The trick is
that the coderef in question is called every time the relationship
needs to be resolved. By referencing some external package-global
you can control what the coderef will return.
The real solution is to have proper runtime join condition
specifications, something like
search( {...}, { join => {
foo => { -foo_opts => {}, bar => { -bar_opts => {}, baz => {} } }
} });
or similar. Making this work correctly and be flexible enough to
not constrain future dev-work is tricky business, and nobody has
invested the time to write up a full-fledged plan.
So until this takes place (you are more than welcome to help by
writing a more detailed spec, preferably in the form of failing
test cases) - until then the global var approach outlined above
is the easy way out.
Hope this was a little helpful :)
Cheers
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