Merge pull request #4303 from PratikFandade/pg_row_to_json

Add the row_to_json Method for diesel postgres

diesel/src/pg/expression/expression_methods.rs

@@ -4,7 +4,8 @@ pub(in crate::pg) use self::private::{
     ArrayOrNullableArray, CombinedNullableValue, InetOrCidr, JsonIndex, JsonOrNullableJson,
     JsonOrNullableJsonOrJsonbOrNullableJsonb, JsonRemoveIndex, JsonbOrNullableJsonb,
     MaybeNullableValue, MultirangeOrNullableMultirange, MultirangeOrRangeMaybeNullable,
-    RangeOrMultirange, RangeOrNullableRange, TextArrayOrNullableTextArray, TextOrNullableText,
+    RangeOrMultirange, RangeOrNullableRange, RecordOrNullableRecord, TextArrayOrNullableTextArray,
+    TextOrNullableText,
 };
 use super::date_and_time::{AtTimeZone, DateTimeLike};
 use super::operators::*;
@@ -3302,7 +3303,7 @@ where
 pub(in crate::pg) mod private {
     use crate::sql_types::{
         Array, Binary, Cidr, Inet, Integer, Json, Jsonb, MaybeNullableType, Multirange, Nullable,
-        OneIsNullable, Range, SingleValue, SqlType, Text,
+        OneIsNullable, Range, Record, SingleValue, SqlType, Text,
     };
     use crate::{Expression, IntoSql};
 
@@ -3640,4 +3641,13 @@ pub(in crate::pg) mod private {
     impl TextArrayOrNullableTextArray for Array<Nullable<Text>> {}
     impl TextArrayOrNullableTextArray for Nullable<Array<Text>> {}
     impl TextArrayOrNullableTextArray for Nullable<Array<Nullable<Text>>> {}
+
+    #[diagnostic::on_unimplemented(
+        message = "`{Self}` is neither `Record<T>` nor `Nullable<Record<T>>`",
+        note = "try to provide an expression that produces one of the expected sql types"
+    )]
+    pub trait RecordOrNullableRecord {}
+
+    impl<T> RecordOrNullableRecord for Record<T> {}
+    impl<T> RecordOrNullableRecord for Nullable<Record<T>> {}
 }

diesel/src/pg/expression/functions.rs

@@ -10,6 +10,7 @@ use crate::pg::expression::expression_methods::MaybeNullableValue;
 use crate::pg::expression::expression_methods::MultirangeOrNullableMultirange;
 use crate::pg::expression::expression_methods::MultirangeOrRangeMaybeNullable;
 use crate::pg::expression::expression_methods::RangeOrNullableRange;
+use crate::pg::expression::expression_methods::RecordOrNullableRecord;
 use crate::pg::expression::expression_methods::TextArrayOrNullableTextArray;
 use crate::sql_types::*;
 
@@ -2234,3 +2235,47 @@ define_sql_function! {
         values: Arr2
     ) -> Arr2::Out;
 }
+
+#[cfg(feature = "postgres_backend")]
+define_sql_function! {
+    /// This function `row_to_json` takes a Record type as an input and converts it to JSON.
+    ///
+    /// # 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::row_to_json;
+    /// #     use diesel::dsl::sql;
+    /// #     use diesel::sql_types::{Record, Text, Integer};
+    /// #     use serde_json::Value;
+    /// #     let connection = &mut establish_connection();
+    ///
+    /// let json_value = diesel::select(row_to_json(sql::<Record<(Text, Integer)>>(
+    ///     "ROW('John', 30)"
+    /// )))
+    /// .get_result::<Value>(connection)?;
+    /// let expected: Value = serde_json::json!({
+    ///     "f1": "John",
+    ///     "f2": 30
+    /// });
+    /// assert_eq!(expected, json_value);
+    ///
+    /// let json_value = diesel::select(row_to_json(sql::<Record<()>>("ROW()")))
+    /// .get_result::<Value>(connection)?;
+    /// let expected: Value = serde_json::json!({});
+    /// assert_eq!(expected, json_value);
+    ///
+    /// #    Ok(())
+    /// # }
+    /// ```
+    #[sql_name = "row_to_json"]
+    fn row_to_json<R: RecordOrNullableRecord + MaybeNullableValue<Json>>(record: R) -> R::Out;
+}

diesel/src/pg/expression/helper_types.rs

@@ -543,3 +543,8 @@ pub type jsonb_object<A> = super::functions::jsonb_object<SqlTypeOf<A>, A>;
 #[cfg(feature = "postgres_backend")]
 pub type jsonb_object_with_keys_and_values<K, V> =
     super::functions::jsonb_object_with_keys_and_values<SqlTypeOf<K>, SqlTypeOf<V>, K, V>;
+
+/// Return type of [`row_to_json(record)`](super::functions::row_to_json())
+#[allow(non_camel_case_types)]
+#[cfg(feature = "postgres_backend")]
+pub type row_to_json<R> = super::functions::row_to_json<SqlTypeOf<R>, R>;

diesel_derives/tests/auto_type.rs

@@ -52,7 +52,8 @@ table! {
         multirange -> Multirange<Integer>,
         timestamptz -> Timestamptz,
         name -> Text,
-        text_array -> Array<Text>
+        text_array -> Array<Text>,
+        record -> Record<(Integer, Text, Date)>,
     }
 }
 
@@ -449,6 +450,7 @@ fn postgres_functions() -> _ {
         jsonb_array_length(pg_extras::jsonb),
         jsonb_object(pg_extras::text_array),
         jsonb_object_with_keys_and_values(pg_extras::text_array, pg_extras::text_array),
+        row_to_json(pg_extras::record),
     )
 }