Trait diesel:: expression:: SelectableExpression
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pub trait SelectableExpression<QS, Type = Self::SqlType>: Expression { }
Indicates that an expression can be selected from a source. The second type argument is optional, but is used to indicate that the right side of a left outer join is nullable, even if it wasn't before.
Columns will implement this for their table. Certain special types, like
CountStar
and Bound
will implement this for
all sources. All other expressions will inherit this from their children.
Implementors
impl<QS, ST> SelectableExpression<QS> for SqlLiteral<ST>
impl<T: ?Sized, ST, QS> SelectableExpression<QS, ST> for Box<T> where T: SelectableExpression<QS, ST>, Box<T>: Expression
impl<'a, T: ?Sized, ST, QS> SelectableExpression<QS, ST> for &'a T where T: SelectableExpression<QS, ST>, &'a T: Expression