add jsonb_set support

diesel/src/pg/expression/functions.rs

@@ -2398,3 +2398,86 @@ define_sql_function! {
         J: JsonbOrNullableJsonb + CombinedAllNullableValue<Jsonb, B>
     >(base: B, from_json: J) -> J::Out;
 }
+
+#[cfg(feature = "postgres_backend")]
+define_sql_function! {
+    /// Returns target with the item designated by path replaced by new_value,
+    ///     or with new_value added if create_if_missing is true (which is the default)
+    ///     and the item designated by path does not exist.
+    ///
+    /// It can't set path in scalar
+    ///
+    /// All earlier steps in the path must exist, or the target is returned unchanged.
+    /// As with the path oriented operators, negative integers that appear in the path count from the end of JSON arrays.
+    /// If the last path step is an array index that is out of range,
+    ///     and create_if_missing is true, the new value is added at the beginning of the array if the index is negative,
+    ///     or at the end of the array if it is positive.
+    ///
+    /// # Example
+    ///
+    /// ```rust
+    /// # include!("../../doctest_setup.rs");
+    /// #
+    /// # fn main() {
+    /// #     #[cfg(feature = "serde_json")]
+    /// #     run_test().unwrap();
+    /// # }
+    /// #
+    /// # #[cfg(feature = "serde_json")]
+    /// # fn run_test() -> QueryResult<()> {
+    /// #     use diesel::dsl::jsonb_set;
+    /// #     use diesel::sql_types::{Jsonb,Array, Json, Nullable, Text};
+    /// #     use serde_json::{json,Value};
+    /// #     let connection = &mut establish_connection();
+    ///
+    /// let result = diesel::select(jsonb_set::<Jsonb, Array<Text>, _, _, _>(
+    ///         json!([{"f1":1,"f2":null},2,null,3]),
+    ///         vec!["0","f1"],
+    ///         json!([2,3,4])
+    ///     )).get_result::<Value>(connection)?;
+    /// let expected: Value = json!([{"f1": [2, 3, 4], "f2": null}, 2, null, 3]);
+    /// assert_eq!(result, expected);
+    ///
+    /// let result = diesel::select(jsonb_set::<Jsonb, Array<Text>, _, _, _>(
+    ///         json!([{"odd":[2,4,6,8]}]),
+    ///         // not vec!["odd"], cannot set path in scalar
+    ///         vec!["0","odd"],
+    ///         json!([1,3,5,7])
+    ///     )).get_result::<Value>(connection)?;
+    /// let expected: Value = json!([{"odd":[1,3,5,7]}]);
+    /// assert_eq!(result, expected);
+    ///
+    /// let empty:Vec<String> = Vec::new();
+    /// let result = diesel::select(jsonb_set::<Nullable<Jsonb>, Array<Nullable<Text>>, _, _, _>(
+    ///         None::<Value>,
+    ///         empty,
+    ///         None::<Value>
+    ///     )).get_result::<Option<Value>>(connection)?;
+    /// assert!(result.is_none());
+    ///
+    /// let empty:Vec<String> = Vec::new();
+    /// let result = diesel::select(jsonb_set::<Jsonb, Array<Nullable<Text>>, _, _, _>(
+    ///         // cannot be json!(null)
+    ///         json!([]),
+    ///         empty,
+    ///         json!(null)
+    ///     )).get_result::<Value>(connection)?;
+    /// let expected = json!([]);
+    /// assert_eq!(result, expected);
+    ///
+    /// let result = diesel::select(jsonb_set::<Jsonb, Nullable<Array<Nullable<Text>>>, _, _, _,>(
+    ///         json!(null),
+    ///         None::<Vec<String>>,
+    ///         json!({"foo": 42})
+    ///     )).get_result::<Option<Value>>(connection)?;
+    /// assert!(result.is_none());
+    ///
+    ///
+    /// #     Ok(())
+    /// # }
+    /// ```
+    fn jsonb_set<
+        E: JsonbOrNullableJsonb + SingleValue,
+        Arr: TextArrayOrNullableTextArray + CombinedNullableValue<E,Jsonb>
+    >(base: E, path: Arr, new_value: E) -> Arr::Out;
+}

diesel/src/pg/expression/helper_types.rs

@@ -592,3 +592,8 @@ pub type json_populate_record<B, J> =
 #[cfg(feature = "postgres_backend")]
 pub type jsonb_populate_record<B, J> =
     super::functions::jsonb_populate_record<SqlTypeOf<B>, SqlTypeOf<J>, B, J>;
+
+/// Return type of [`jsonb_set(base, path, new_value)`](super::functions::jsonb_set())
+#[allow(non_camel_case_types)]
+#[cfg(feature = "postgres_backend")]
+pub type jsonb_set<B, J, R> = super::functions::jsonb_set<SqlTypeOf<B>, SqlTypeOf<J>, B, J, R>;

diesel_derives/tests/auto_type.rs

@@ -461,6 +461,7 @@ fn postgres_functions() -> _ {
         row_to_json(pg_extras::record),
         json_populate_record(pg_extras::record, pg_extras::json),
         jsonb_populate_record(pg_extras::record, pg_extras::jsonb),
+        jsonb_set(pg_extras::jsonb, pg_extras::text_array, pg_extras::jsonb),
     )
 }