diesel/query_builder/
where_clause.rs

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1use super::from_clause::AsQuerySource;
2use super::*;
3use crate::backend::DieselReserveSpecialization;
4use crate::expression::grouped::Grouped;
5use crate::expression::operators::{And, Or};
6use crate::expression::*;
7use crate::sql_types::BoolOrNullableBool;
8
9/// Add `Predicate` to the current `WHERE` clause, joining with `AND` if
10/// applicable.
11pub trait WhereAnd<Predicate> {
12    /// What is the type of the resulting `WHERE` clause?
13    type Output;
14
15    /// See the trait-level docs.
16    fn and(self, predicate: Predicate) -> Self::Output;
17}
18
19/// Add `Predicate` to the current `WHERE` clause, joining with `OR` if
20/// applicable.
21pub trait WhereOr<Predicate> {
22    /// What is the type of the resulting `WHERE` clause?
23    type Output;
24
25    /// See the trait-level docs.
26    fn or(self, predicate: Predicate) -> Self::Output;
27}
28
29/// Represents that a query has no `WHERE` clause.
30#[derive(Debug, Clone, Copy, QueryId)]
31pub struct NoWhereClause;
32
33impl<DB> QueryFragment<DB> for NoWhereClause
34where
35    DB: Backend + DieselReserveSpecialization,
36{
37    fn walk_ast<'b>(&'b self, _: AstPass<'_, 'b, DB>) -> QueryResult<()> {
38        Ok(())
39    }
40}
41
42impl<Predicate> WhereAnd<Predicate> for NoWhereClause
43where
44    Predicate: Expression,
45    Predicate::SqlType: BoolOrNullableBool,
46{
47    type Output = WhereClause<Predicate>;
48
49    fn and(self, predicate: Predicate) -> Self::Output {
50        WhereClause(predicate)
51    }
52}
53
54impl<Predicate> WhereOr<Predicate> for NoWhereClause
55where
56    Predicate: Expression,
57    Predicate::SqlType: BoolOrNullableBool,
58{
59    type Output = WhereClause<Predicate>;
60
61    fn or(self, predicate: Predicate) -> Self::Output {
62        WhereClause(predicate)
63    }
64}
65
66impl<DB> From<NoWhereClause> for BoxedWhereClause<'_, DB> {
67    fn from(_: NoWhereClause) -> Self {
68        BoxedWhereClause::None
69    }
70}
71
72/// The `WHERE` clause of a query.
73#[derive(Debug, Clone, Copy, QueryId)]
74pub struct WhereClause<Expr>(Expr);
75
76impl<DB, Expr> QueryFragment<DB> for WhereClause<Expr>
77where
78    DB: Backend + DieselReserveSpecialization,
79    Expr: QueryFragment<DB>,
80{
81    fn walk_ast<'b>(&'b self, mut out: AstPass<'_, 'b, DB>) -> QueryResult<()> {
82        out.push_sql(" WHERE ");
83        self.0.walk_ast(out.reborrow())?;
84        Ok(())
85    }
86}
87
88impl<Expr, Predicate> WhereAnd<Predicate> for WhereClause<Expr>
89where
90    Expr: Expression,
91    Expr::SqlType: BoolOrNullableBool,
92    Predicate: Expression,
93    Predicate::SqlType: BoolOrNullableBool,
94{
95    type Output = WhereClause<Grouped<And<Expr, Predicate>>>;
96
97    fn and(self, predicate: Predicate) -> Self::Output {
98        WhereClause(Grouped(And::new(self.0, predicate)))
99    }
100}
101
102impl<Expr, Predicate> WhereOr<Predicate> for WhereClause<Expr>
103where
104    Expr: Expression,
105    Expr::SqlType: BoolOrNullableBool,
106    Predicate: Expression,
107    Predicate::SqlType: BoolOrNullableBool,
108{
109    type Output = WhereClause<Grouped<Or<Expr, Predicate>>>;
110
111    fn or(self, predicate: Predicate) -> Self::Output {
112        WhereClause(Grouped(Or::new(self.0, predicate)))
113    }
114}
115
116impl<'a, DB, Predicate> From<WhereClause<Predicate>> for BoxedWhereClause<'a, DB>
117where
118    DB: Backend,
119    Predicate: QueryFragment<DB> + Send + 'a,
120{
121    fn from(where_clause: WhereClause<Predicate>) -> Self {
122        BoxedWhereClause::Where(Box::new(where_clause.0))
123    }
124}
125
126/// Marker trait indicating that a `WHERE` clause is valid for a given query
127/// source.
128pub trait ValidWhereClause<QS> {}
129
130impl<QS> ValidWhereClause<QS> for NoWhereClause {}
131
132impl<QS, Expr> ValidWhereClause<QS> for WhereClause<Expr>
133where
134    Expr: AppearsOnTable<QS::QuerySource>,
135    QS: AsQuerySource,
136{
137}
138
139impl<Expr> ValidWhereClause<NoFromClause> for WhereClause<Expr> where
140    Expr: AppearsOnTable<NoFromClause>
141{
142}
143
144#[allow(missing_debug_implementations)] // We can't...
145pub enum BoxedWhereClause<'a, DB> {
146    Where(Box<dyn QueryFragment<DB> + Send + 'a>),
147    None,
148}
149
150impl<DB> QueryFragment<DB> for BoxedWhereClause<'_, DB>
151where
152    DB: Backend + DieselReserveSpecialization,
153{
154    fn walk_ast<'b>(&'b self, mut out: AstPass<'_, 'b, DB>) -> QueryResult<()> {
155        match *self {
156            BoxedWhereClause::Where(ref where_clause) => {
157                out.push_sql(" WHERE ");
158                where_clause.walk_ast(out)
159            }
160            BoxedWhereClause::None => Ok(()),
161        }
162    }
163}
164
165impl<DB> QueryId for BoxedWhereClause<'_, DB> {
166    type QueryId = ();
167
168    const HAS_STATIC_QUERY_ID: bool = false;
169}
170
171impl<'a, DB, Predicate> WhereAnd<Predicate> for BoxedWhereClause<'a, DB>
172where
173    DB: Backend + 'a,
174    Predicate: QueryFragment<DB> + Send + 'a,
175    Grouped<And<Box<dyn QueryFragment<DB> + Send + 'a>, Predicate>>: QueryFragment<DB>,
176{
177    type Output = Self;
178
179    fn and(self, predicate: Predicate) -> Self::Output {
180        use self::BoxedWhereClause::Where;
181
182        match self {
183            Where(where_clause) => Where(Box::new(Grouped(And::new(where_clause, predicate)))),
184            BoxedWhereClause::None => Where(Box::new(predicate)),
185        }
186    }
187}
188
189impl<'a, DB, Predicate> WhereOr<Predicate> for BoxedWhereClause<'a, DB>
190where
191    DB: Backend + 'a,
192    Predicate: QueryFragment<DB> + Send + 'a,
193    Grouped<Or<Box<dyn QueryFragment<DB> + Send + 'a>, Predicate>>: QueryFragment<DB>,
194{
195    type Output = Self;
196
197    fn or(self, predicate: Predicate) -> Self::Output {
198        use self::BoxedWhereClause::Where;
199
200        match self {
201            Where(where_clause) => Where(Box::new(Grouped(Or::new(where_clause, predicate)))),
202            BoxedWhereClause::None => Where(Box::new(predicate)),
203        }
204    }
205}
diesel/query_builder/where_clause.rs

diesel/query_builder/
where_clause.rs
