diesel/pg/query_builder/
only.rs

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1use crate::expression::{Expression, ValidGrouping};
2use crate::pg::Pg;
3use crate::query_builder::{AsQuery, AstPass, FromClause, QueryFragment, QueryId, SelectStatement};
4use crate::query_source::QuerySource;
5use crate::result::QueryResult;
6use crate::{JoinTo, SelectableExpression, Table};
7
8/// Represents a query with an `ONLY` clause.
9#[derive(Debug, Clone, Copy, Default)]
10pub struct Only<S> {
11    pub(crate) source: S,
12}
13
14impl<S> QueryId for Only<S>
15where
16    Self: 'static,
17    S: QueryId,
18{
19    type QueryId = Self;
20    const HAS_STATIC_QUERY_ID: bool = <S as QueryId>::HAS_STATIC_QUERY_ID;
21}
22
23impl<S> QuerySource for Only<S>
24where
25    S: Table + Clone,
26    <S as QuerySource>::DefaultSelection: ValidGrouping<()> + SelectableExpression<Only<S>>,
27{
28    type FromClause = Self;
29    type DefaultSelection = <S as QuerySource>::DefaultSelection;
30
31    fn from_clause(&self) -> Self::FromClause {
32        self.clone()
33    }
34
35    fn default_selection(&self) -> Self::DefaultSelection {
36        self.source.default_selection()
37    }
38}
39
40impl<S> QueryFragment<Pg> for Only<S>
41where
42    S: QueryFragment<Pg>,
43{
44    fn walk_ast<'b>(&'b self, mut pass: AstPass<'_, 'b, Pg>) -> QueryResult<()> {
45        pass.push_sql(" ONLY ");
46        self.source.walk_ast(pass.reborrow())?;
47        Ok(())
48    }
49}
50
51impl<S> AsQuery for Only<S>
52where
53    S: Table + Clone,
54    <S as QuerySource>::DefaultSelection: ValidGrouping<()> + SelectableExpression<Only<S>>,
55{
56    type SqlType = <<Self as QuerySource>::DefaultSelection as Expression>::SqlType;
57    type Query = SelectStatement<FromClause<Self>>;
58
59    fn as_query(self) -> Self::Query {
60        SelectStatement::simple(self)
61    }
62}
63
64impl<S, T> JoinTo<T> for Only<S>
65where
66    S: JoinTo<T>,
67    T: Table,
68    S: Table,
69{
70    type FromClause = <S as JoinTo<T>>::FromClause;
71    type OnClause = <S as JoinTo<T>>::OnClause;
72
73    fn join_target(rhs: T) -> (Self::FromClause, Self::OnClause) {
74        <S as JoinTo<T>>::join_target(rhs)
75    }
76}
77impl<S> Table for Only<S>
78where
79    S: Table + Clone + AsQuery,
80
81    <S as Table>::PrimaryKey: SelectableExpression<Only<S>>,
82    <S as Table>::AllColumns: SelectableExpression<Only<S>>,
83    <S as QuerySource>::DefaultSelection: ValidGrouping<()> + SelectableExpression<Only<S>>,
84{
85    type PrimaryKey = <S as Table>::PrimaryKey;
86    type AllColumns = <S as Table>::AllColumns;
87
88    fn primary_key(&self) -> Self::PrimaryKey {
89        self.source.primary_key()
90    }
91
92    fn all_columns() -> Self::AllColumns {
93        S::all_columns()
94    }
95}
diesel/pg/query_builder/only.rs

diesel/pg/query_builder/
only.rs
