Trait diesel::expression::BoxableExpression
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[src]
pub trait BoxableExpression<QS, ST, DB> where DB: Backend, Self: Expression, Self: SelectableExpression<QS, ST>, Self: NonAggregate, Self: QueryFragment<DB> { }
Helper trait used when boxing expressions. This exists to work around the
fact that Rust will not let us use non-core types as bounds on a trait
object (you could not return Box<Expression+NonAggregate>
)
Implementors
impl<QS, T, ST, DB> BoxableExpression<QS, ST, DB> for T where DB: Backend, T: Expression, T: SelectableExpression<QS, ST>, T: NonAggregate, T: QueryFragment<DB>