How can I use WHERE on a ManagedSet? - orm

Question

I have a many-to-many relation, having P, PF and F I want to filter P using F through PF. Like:
final query = Query<P>(context)
..where( (p)=>p.pfSet.firstWhere( (pf)=>pf.f.cod == 1 ).f ).isNotNull();
and the classes:
class P extends ManagedObject<_P> implements _P {}
class _P{
#primaryKey
int cod;
...
ManagedSet<ProdutoFilial> pfSet;
}
class PF extends ManagedObject<_PF> implements _PF {}
class _PF{
#primaryKey
int cod;
#(Relate #pfSet)
P p;
#(Relate #pfSet)
F f;
bool active;
}
class F extends ManagedObject<_F> implements _F {}
class _F{
#primaryKey
int cod;
...
ManagedSet<ProdutoFilial> pfSet;
}
How can I filter this?

Answer 1

Can use a own query that will stay on where:
..predicate = QueryPredicate(
" exists (select f.cod from pf where pf.fcod = #fcod and pf.pcod = p.cod) ",
{ "fcod": 1 });
if you use join in your code query the table name will change.

Answer 2

QueryPredicate is not a very good solution because you cannot set a condition in a joined table (we don't know the aliases of joined tables). I created my own procedure - try it:
QueryExpression<dynamic, dynamic> RelationWhereExt(Query query, List<String> links) {
ManagedEntity e = query.entity;
KeyPath path;
ManagedPropertyDescription property;
links.forEach((link) {
property = e.properties[link];
if (path==null){
// рутовое условие
path = KeyPath(property);
} else {
// следующие условия
path.add(property);
}
if (property is ManagedRelationshipDescription) {
e = (property as ManagedRelationshipDescription).destinationEntity; // меняем entity
}
});
QueryExpression<dynamic, dynamic> queryExpression = QueryExpression<dynamic, dynamic>(path);
(query as MySqlQuery).expressions.add(queryExpression);
return queryExpression;
}
In you case: RelationWhereExt(query, ['pfSet', 'f']).isNotNull();