1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35
use expression::Expression; use query_builder::{AsQuery, Query}; use query_source::Table; /// This trait is not yet part of Diesel's public API. It may change in the /// future without a major version bump. /// /// This trait exists as a stop-gap for users who need to use `GROUP BY` in /// their queries, so that they are not forced to drop entirely to raw SQL. The /// arguments to `group_by` are not checked, nor is the select statement /// forced to be valid. /// /// Since Diesel otherwise assumes that you have no `GROUP BY` clause (which /// would mean that mixing an aggregate and non aggregate expression in the same /// query is an error), you may need to use `sql` for your select clause. pub trait GroupByDsl<Expr: Expression> { /// The type returned by `.group_by` type Output: Query; /// See the trait documentation. fn group_by(self, expr: Expr) -> Self::Output; } impl<T, Expr> GroupByDsl<Expr> for T where Expr: Expression, T: Table + AsQuery, T::Query: GroupByDsl<Expr>, { type Output = <T::Query as GroupByDsl<Expr>>::Output; fn group_by(self, expr: Expr) -> Self::Output { self.as_query().group_by(expr) } }