Merge pull request diesel-rs#4314 from meeshal/add_is_json_expression

add is_json and is_not_json expression methods

Author: weiznich

diesel/src/pg/expression/expression_methods.rs

@@ -158,6 +158,82 @@ pub trait PgExpressionMethods: Expression + Sized {
     {
         Grouped(IsContainedBy::new(self, other.as_expression()))
     }
+
+    /// Creates a PostgreSQL `IS JSON` expression.
+    /// Requires PostgreSQL>=16
+    ///
+    /// This operator returns true whether an object is a valid JSON
+    ///
+    /// # Example
+    ///
+    /// ```rust,no_run
+    /// # include!("../../doctest_setup.rs");
+    /// #
+    /// # fn main() {
+    /// #     run_test().unwrap();
+    /// # }
+    /// #
+    /// # fn run_test() -> QueryResult<()> {
+    /// #     use std::collections::Bound;
+    /// #     use diesel::sql_types::Text;
+    /// #
+    /// #     let conn = &mut establish_connection();
+    /// #
+    ///
+    /// let res = diesel::select(("1".into_sql::<Text>().is_json())).get_result::<bool>(conn)?;
+    /// assert_eq!(res, true);
+    /// let res = diesel::select(("[1,2,3]".into_sql::<Text>().is_json())).get_result::<bool>(conn)?;
+    /// assert_eq!(res, true);
+    /// let res = diesel::select(("{\"products\": [1,2,3]}".into_sql::<Text>().is_json())).get_result::<bool>(conn)?;
+    /// assert_eq!(res, true);
+    /// let res = diesel::select(("(1,2,3)".into_sql::<Text>().is_json())).get_result::<bool>(conn)?;
+    /// assert_eq!(res, false);
+    /// #
+    /// #     Ok(())
+    /// # }
+    /// ```
+    #[allow(clippy::wrong_self_convention)] // This is named after the sql operator
+    fn is_json(self) -> dsl::IsJson<Self> {
+        IsJson::new(self)
+    }
+
+    /// Creates a PostgreSQL `IS NOT JSON` expression.
+    /// Requires PostgreSQL>=16
+    ///
+    /// This operator returns true whether an object is not a valid JSON
+    ///
+    /// # Example
+    ///
+    /// ```rust,no_run
+    /// # include!("../../doctest_setup.rs");
+    /// #
+    /// # fn main() {
+    /// #     run_test().unwrap();
+    /// # }
+    /// #
+    /// # fn run_test() -> QueryResult<()> {
+    /// #     use std::collections::Bound;
+    /// #     use diesel::sql_types::Text;
+    /// #
+    /// #     let conn = &mut establish_connection();
+    /// #
+    ///
+    /// let res = diesel::select(("1".into_sql::<Text>().is_not_json())).get_result::<bool>(conn)?;
+    /// assert_eq!(res, false);
+    /// let res = diesel::select(("[1,2,3]".into_sql::<Text>().is_not_json())).get_result::<bool>(conn)?;
+    /// assert_eq!(res, false);
+    /// let res = diesel::select(("{\"products\": [1,2,3]}".into_sql::<Text>().is_not_json())).get_result::<bool>(conn)?;
+    /// assert_eq!(res, false);
+    /// let res = diesel::select(("(1,2,3)".into_sql::<Text>().is_not_json())).get_result::<bool>(conn)?;
+    /// assert_eq!(res, true);
+    /// #
+    /// #     Ok(())
+    /// # }
+    /// ```
+    #[allow(clippy::wrong_self_convention)] // This is named after the sql operator
+    fn is_not_json(self) -> dsl::IsNotJson<Self> {
+        IsNotJson::new(self)
+    }
 }
 
 impl<T: Expression> PgExpressionMethods for T {}

diesel/src/pg/expression/helper_types.rs

@@ -130,6 +130,14 @@ pub type IntersectionRange<Lhs, Rhs> = Intersection<Lhs, Rhs>;
 #[cfg(feature = "postgres_backend")]
 pub type NullsFirst<T> = super::operators::NullsFirst<T>;
 
+/// The return type of [`expr.is_json()`](super::expression_methods::PgExpressionMethods::is_json)
+#[cfg(feature = "postgres_backend")]
+pub type IsJson<T> = super::operators::IsJson<T>;
+
+/// The return type of [`expr.is_not_json()`](super::expression_methods::PgExpressionMethods::is_not_json)
+#[cfg(feature = "postgres_backend")]
+pub type IsNotJson<T> = super::operators::IsNotJson<T>;
+
 /// The return type of [`expr.nulls_last()`](super::expression_methods::PgSortExpressionMethods::nulls_last)
 #[cfg(feature = "postgres_backend")]
 pub type NullsLast<T> = super::operators::NullsLast<T>;

diesel/src/pg/expression/operators.rs

@@ -23,6 +23,8 @@ infix_operator!(SimilarTo, " SIMILAR TO ", backend: Pg);
 infix_operator!(NotSimilarTo, " NOT SIMILAR TO ", backend: Pg);
 postfix_operator!(NullsFirst, " NULLS FIRST", NotSelectable, backend: Pg);
 postfix_operator!(NullsLast, " NULLS LAST", NotSelectable, backend: Pg);
+postfix_operator!(IsJson, " IS JSON", backend: Pg);
+postfix_operator!(IsNotJson, " IS NOT JSON", backend: Pg);
 infix_operator!(ContainsNet, " >> ", backend: Pg);
 infix_operator!(ContainsNetLoose, " >>= ", backend: Pg);
 infix_operator!(IsContainedByNet, " << ", backend: Pg);

diesel_derives/tests/auto_type.rs

@@ -282,6 +282,8 @@ fn test_pg_jsonb_expression_methods() -> _ {
         .and(pg_extras::jsonb.remove(1_i32).eq(pg_extras::jsonb))
         .and(pg_extras::jsonb.remove_by_path(v).eq(pg_extras::jsonb))
         .and(pg_extras::jsonb.is_contained_by(pg_extras::jsonb))
+        .and(pg_extras::id.is_json())
+        .and(pg_extras::id.is_not_json())
 }
 
 #[cfg(feature = "postgres")]