diesel/expression/functions/
mod.rs

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1//! Helper macros to define custom sql functions
2
3#[doc(inline)]
4pub use diesel_derives::define_sql_function;
5
6#[doc(inline)]
7#[cfg(all(feature = "with-deprecated", not(feature = "without-deprecated")))]
8pub use diesel_derives::sql_function_proc as sql_function;
9
10#[macro_export]
11#[doc(hidden)]
12#[cfg(all(feature = "with-deprecated", not(feature = "without-deprecated")))]
13macro_rules! no_arg_sql_function_body_except_to_sql {
14    ($type_name:ident, $return_type:ty, $docs:expr) => {
15        #[allow(non_camel_case_types)]
16        #[doc=$docs]
17        #[derive(
18            Debug, Clone, Copy, $crate::query_builder::QueryId, $crate::expression::ValidGrouping,
19        )]
20        pub struct $type_name;
21
22        impl $crate::expression::Expression for $type_name {
23            type SqlType = $return_type;
24        }
25
26        impl<QS> $crate::expression::SelectableExpression<QS> for $type_name {}
27
28        impl<QS> $crate::expression::AppearsOnTable<QS> for $type_name {}
29    };
30}
31
32#[macro_export]
33#[doc(hidden)]
34#[cfg(all(feature = "with-deprecated", not(feature = "without-deprecated")))]
35macro_rules! no_arg_sql_function_body {
36    ($type_name:ident, $return_type:ty, $docs:expr, $($constraint:ident)::+) => {
37        no_arg_sql_function_body_except_to_sql!($type_name, $return_type, $docs);
38
39        impl<DB> $crate::query_builder::QueryFragment<DB> for $type_name where
40            DB: $crate::backend::Backend + $($constraint)::+,
41        {
42            fn walk_ast<'b>(&'b self, mut out: $crate::query_builder::AstPass<'_, 'b, DB>) -> $crate::result::QueryResult<()>
43            {
44                out.push_sql(concat!(stringify!($type_name), "()"));
45                Ok(())
46            }
47        }
48    };
49
50    ($type_name:ident, $return_type:ty, $docs:expr) => {
51        no_arg_sql_function_body_except_to_sql!($type_name, $return_type, $docs);
52
53        impl<DB> $crate::query_builder::QueryFragment<DB> for $type_name where
54            DB: $crate::backend::Backend,
55        {
56            fn walk_ast<'b>(&'b self, mut out: $crate::query_builder::AstPass<'_, 'b, DB>) -> $crate::result::QueryResult<()> {
57                out.push_sql(concat!(stringify!($type_name), "()"));
58                Ok(())
59            }
60        }
61    };
62}
63
64#[macro_export]
65/// Declare a 0 argument SQL function for use in your code. This will generate a
66/// unit struct, which is an expression representing calling this function. See
67/// [`now`](crate::expression::dsl::now) for example output. `now` was
68/// generated using:
69///
70/// ```no_run
71/// # pub use diesel::*;
72/// no_arg_sql_function!(now, sql_types::Timestamp, "Represents the SQL NOW() function");
73/// # fn main() {}
74/// ```
75///
76/// You can optionally pass the name of a trait, as a constraint for backends which support the
77/// function.
78#[deprecated(
79    since = "2.0.0",
80    note = "Use `define_sql_function!` instead. See `CHANGELOG.md` for migration instructions"
81)]
82#[cfg(all(feature = "with-deprecated", not(feature = "without-deprecated")))]
83macro_rules! no_arg_sql_function {
84    ($type_name:ident, $return_type:ty) => {
85        no_arg_sql_function!($type_name, $return_type, "");
86    };
87
88    ($type_name:ident, $return_type:ty, $docs:expr) => {
89        no_arg_sql_function_body!($type_name, $return_type, $docs);
90    };
91
92    ($type_name:ident, $return_type:ty, $docs:expr, $($constraint:ident)::+) => {
93        no_arg_sql_function_body!($type_name, $return_type, $docs, $($constraint)::+);
94    };
95}
96
97pub(crate) mod aggregate_folding;
98pub(crate) mod aggregate_ordering;
99pub(crate) mod date_and_time;
100pub(crate) mod helper_types;
diesel/expression/functions/mod.rs

diesel/expression/functions/
mod.rs
