Trait diesel::expression::ValidGrouping
source · pub trait ValidGrouping<GroupByClause> {
type IsAggregate;
}
Expand description
Is this expression valid for a given group by clause?
Implementations of this trait must ensure that aggregate expressions are not mixed with non-aggregate expressions.
For generic types, you can determine if your sub-expressions can appear
together using the MixedAggregates
trait.
GroupByClause
will be a tuple containing the set of expressions appearing
in the GROUP BY
portion of the query. If there is no GROUP BY
, it will
be ()
.
This trait can be derived
Required Associated Types§
sourcetype IsAggregate
type IsAggregate
Is this expression aggregate?
This type should always be one of the structs in the is_aggregate
module. See the documentation of those structs for more details.