diesel/query_dsl/
group_by_dsl.rs

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1use crate::dsl;
2use crate::expression::Expression;
3use crate::expression::TypedExpressionType;
4use crate::expression::ValidGrouping;
5use crate::query_builder::FromClause;
6use crate::query_builder::{AsQuery, SelectStatement};
7use crate::query_source::Table;
8
9/// The `group_by` method
10///
11/// This trait should not be relied on directly by most apps. Its behavior is
12/// provided by [`QueryDsl`]. However, you may need a where clause on this trait
13/// to call `group_by` from generic code.
14///
15/// [`QueryDsl`]: crate::QueryDsl
16pub trait GroupByDsl<Expr: Expression> {
17    /// The type returned by `.group_by`
18    type Output;
19
20    /// See the trait documentation.
21    fn group_by(self, expr: Expr) -> dsl::GroupBy<Self, Expr>;
22}
23
24impl<T, Expr> GroupByDsl<Expr> for T
25where
26    Expr: Expression,
27    T: Table + AsQuery<Query = SelectStatement<FromClause<T>>>,
28    T::DefaultSelection: Expression<SqlType = T::SqlType> + ValidGrouping<()>,
29    T::SqlType: TypedExpressionType,
30    T::Query: GroupByDsl<Expr>,
31{
32    type Output = dsl::GroupBy<SelectStatement<FromClause<T>>, Expr>;
33
34    fn group_by(self, expr: Expr) -> dsl::GroupBy<Self, Expr> {
35        self.as_query().group_by(expr)
36    }
37}
diesel/query_dsl/group_by_dsl.rs

diesel/query_dsl/
group_by_dsl.rs
