Add Decimal in NUMERIC_TYPES

diesel_derives/src/table.rs

@@ -586,6 +586,7 @@ fn is_numeric(ty: &syn::TypePath) -> bool {
         "Int8",
         "Bigint",
         "BigSerial",
+        "Decimal",
         "Float",
         "Float4",
         "Float8",

diesel_tests/tests/lib.rs

@@ -37,6 +37,8 @@ mod limit_offset;
 mod macros;
 #[cfg(feature = "postgres")]
 mod only;
+#[cfg(not(feature = "sqlite"))]
+mod operations;
 mod order;
 mod perf_details;
 #[cfg(feature = "postgres")]

diesel_tests/tests/operations.rs

@@ -0,0 +1,56 @@
+use std::str::FromStr;
+
+use crate::schema::*;
+use bigdecimal::BigDecimal;
+use diesel::{insert_into, prelude::*, update};
+
+diesel::table! {
+    bigdecimal_table (id) {
+        id -> Integer,
+        big_decimal -> Decimal,
+    }
+}
+
+#[derive(Debug, Insertable, Queryable, Selectable)]
+#[diesel(table_name = bigdecimal_table)]
+struct CustomBigDecimal {
+    pub id: i32,
+    pub big_decimal: BigDecimal,
+}
+
+#[test]
+fn big_decimal_add() {
+    let connection = &mut connection();
+
+    let custom_value = CustomBigDecimal {
+        id: 1,
+        big_decimal: BigDecimal::from_str("0.80").unwrap(),
+    };
+
+    diesel::sql_query(
+        "
+        CREATE TEMPORARY TABLE bigdecimal_table (
+            id SERIAL PRIMARY KEY,
+            big_decimal DECIMAL(8,2) NOT NULL
+            );
+        ",
+    )
+    .execute(connection)
+    .unwrap();
+
+    insert_into(bigdecimal_table::table)
+        .values(&custom_value)
+        .execute(connection)
+        .unwrap();
+
+    let val = BigDecimal::from_str("0.1").unwrap();
+
+    update(bigdecimal_table::table)
+        .set(bigdecimal_table::big_decimal.eq(bigdecimal_table::big_decimal + val))
+        .execute(connection)
+        .unwrap();
+
+    let updated: CustomBigDecimal = bigdecimal_table::table.first(connection).unwrap();
+
+    assert_eq!(BigDecimal::from_str("0.90").unwrap(), updated.big_decimal);
+}