added array_replace pg array function

diesel/src/pg/expression/functions.rs

@@ -748,3 +748,41 @@ define_sql_function! {
     /// ```
     fn array_append<Arr: ArrayOrNullableArray<Inner=T> + SingleValue, T: SingleValue>(a: Arr, e: T) -> Array<T>;
 }
+
+#[cfg(feature = "postgres_backend")]
+define_sql_function! {
+    /// Append an element to the end of an array
+    ///
+    /// # Example
+    ///
+    /// ```rust
+    /// # include!("../../doctest_setup.rs");
+    /// #
+    /// # fn main() {
+    /// #     run_test().unwrap();
+    /// # }
+    /// #
+    /// # fn run_test() -> QueryResult<()> {
+    /// #     use diesel::dsl::array_replace;
+    /// #     use diesel::sql_types::{Nullable, Integer, Array};
+    /// #     let connection = &mut establish_connection();
+    /// let ints = diesel::select(array_replace::<Array<_>, Integer, _, _>(vec![1, 2, 5, 4], 5, 3))
+    ///     .get_result::<Vec<i32>>(connection)?;
+    /// assert_eq!(vec![1, 2, 3, 4], ints);
+    ///
+    /// let ints = diesel::select(array_replace::<Array<_>, Nullable<Integer>, _, _>(vec![Some(1), Some(2), Some(3)], Some(3), None::<i32>))
+    ///     .get_result::<Vec<Option<i32>>>(connection)?;
+    /// assert_eq!(vec![Some(1), Some(2), None], ints);
+    ///
+    /// let ints = diesel::select(array_append::<Nullable<Array<_>>, Integer, _, _>(None::<Vec<i32>>, Some(1), Some(2)))
+    ///     .get_result::<Vec<i32>>(connection)?;
+    /// assert_eq!(vec![None], ints);
+    ///
+    /// let ints = diesel::select(array_append::<Nullable<Array<_>>, Nullable<Integer>, _, _>(None::<Vec<i32>>, None::<i32>))
+    ///     .get_result::<Vec<Option<i32>>>(connection)?;
+    /// assert_eq!(vec![None], ints);
+    /// #     Ok(())
+    /// # }
+    /// ```
+    fn array_replace<Arr: ArrayOrNullableArray<Inner=T> + SingleValue, T: SingleValue>(a: Arr, e: T, r: T) -> Array<T>;
+}

diesel/src/pg/expression/helper_types.rs

@@ -352,3 +352,8 @@ pub type range_merge<R1, R2> = super::functions::range_merge<SqlTypeOf<R1>, SqlT
 #[allow(non_camel_case_types)]
 #[cfg(feature = "postgres_backend")]
 pub type array_append<A, E> = super::functions::array_append<SqlTypeOf<A>, SqlTypeOf<E>, A, E>;
+
+/// Return type of [`array_replace(array, element, replace_with)`](super::functions::array_replace())
+#[allow(non_camel_case_types)]
+#[cfg(feature = "postgres_backend")]
+pub type array_replace<A, E, R> = super::functions::array_replace<SqlTypeOf<A>, SqlTypeOf<E>, A, E, R>;

diesel_derives/tests/auto_type.rs

@@ -411,6 +411,7 @@ fn postgres_functions() -> _ {
             bound,
         ),
         array_append(pg_extras::array, pg_extras::id),
+        array_replace(pg_extras::array, pg_extras::id, pg_extras::id)
     )
 }