diesel/query_dsl/
locking_dsl.rs

1use crate::expression::TypedExpressionType;
2use crate::expression::ValidGrouping;
3use crate::query_builder::AsQuery;
4use crate::query_builder::FromClause;
5use crate::query_builder::SelectStatement;
6use crate::query_source::Table;
7use crate::Expression;
8
9/// Methods related to locking select statements
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 `for_update` from generic code.
14///
15/// [`QueryDsl`]: crate::QueryDsl
16pub trait LockingDsl<Lock> {
17    /// The type returned by `set_lock`. See [`dsl::ForUpdate`] and friends for
18    /// convenient access to this type.
19    ///
20    /// [`dsl::ForUpdate`]: crate::dsl::ForUpdate
21    type Output;
22
23    /// See the trait level documentation
24    fn with_lock(self, lock: Lock) -> Self::Output;
25}
26
27impl<T, Lock> LockingDsl<Lock> for T
28where
29    T: Table + AsQuery<Query = SelectStatement<FromClause<T>>>,
30    T::DefaultSelection: Expression<SqlType = T::SqlType> + ValidGrouping<()>,
31    T::SqlType: TypedExpressionType,
32{
33    type Output = <SelectStatement<FromClause<T>> as LockingDsl<Lock>>::Output;
34
35    fn with_lock(self, lock: Lock) -> Self::Output {
36        self.as_query().with_lock(lock)
37    }
38}
39
40/// Methods related to modifiers on locking select statements
41///
42/// This trait should not be relied on directly by most apps. Its behavior is
43/// provided by [`QueryDsl`]. However, you may need a where clause on this trait
44/// to call `skip_locked` from generic code.
45///
46/// [`QueryDsl`]: crate::QueryDsl
47pub trait ModifyLockDsl<Modifier> {
48    /// The type returned by `modify_lock`. See [`dsl::SkipLocked`] and friends
49    /// for convenient access to this type.
50    ///
51    /// [`dsl::SkipLocked`]: crate::dsl::SkipLocked
52    type Output;
53
54    /// See the trait level documentation
55    fn modify_lock(self, modifier: Modifier) -> Self::Output;
56}
diesel/query_dsl/locking_dsl.rs

diesel/query_dsl/
locking_dsl.rs
