Trait diesel::expression::ValidGrouping[][src]

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-expresssions 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

Associated Types

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.

Implementations on Foreign Types