fix(orm): restore lazy $onUpdate evaluation in buildUpdateSet

drizzle-orm/src/gel-core/dialect.ts

@@ -149,7 +149,9 @@ export class GelDialect {
 		return sql.join(columnNames.flatMap((colName, i) => {
 			const col = tableColumns[colName]!;
 
-			const onUpdateFnResult = col.onUpdateFn?.();
+			// Only invoke the `$onUpdate` callback when the column is absent from
+			// `set` — see drizzle-team/drizzle-orm#5780.
+			const onUpdateFnResult = set[colName] !== undefined ? undefined : col.onUpdateFn?.();
 			const value = set[colName] ?? (is(onUpdateFnResult, SQL) ? onUpdateFnResult : sql.param(onUpdateFnResult, col));
 			const res = sql`${sql.identifier(this.casing.getColumnCasing(col))} = ${value}`;
 

drizzle-orm/src/mysql-core/dialect.ts

@@ -160,7 +160,9 @@ export class MySqlDialect {
 			columnNames.flatMap((colName, i) => {
 				const col = tableColumns[colName]!;
 
-				const onUpdateFnResult = col.onUpdateFn?.();
+				// Only invoke the `$onUpdate` callback when the column is absent
+				// from `set` — see drizzle-team/drizzle-orm#5780.
+				const onUpdateFnResult = set[colName] !== undefined ? undefined : col.onUpdateFn?.();
 				const value = set[colName]
 					?? (is(onUpdateFnResult, SQL)
 						? onUpdateFnResult

drizzle-orm/src/pg-core/dialect.ts

@@ -160,7 +160,12 @@ export class PgDialect {
 		return sql.join(columnNames.flatMap((colName, i) => {
 			const col = tableColumns[colName]!;
 
-			const onUpdateFnResult = col.onUpdateFn?.();
+			// Only invoke the `$onUpdate` callback when the column is absent from
+			// `set` — eagerly calling it for every column would re-introduce the
+			// regression in #5780 where side-effecting callbacks (logging,
+			// throwing, reading external state) fire on every UPDATE even when
+			// the caller explicitly provided the column value.
+			const onUpdateFnResult = set[colName] !== undefined ? undefined : col.onUpdateFn?.();
 			const value = set[colName] ?? (is(onUpdateFnResult, SQL) ? onUpdateFnResult : sql.param(onUpdateFnResult, col));
 			const res = sql`${sql.identifier(this.casing.getColumnCasing(col))} = ${value}`;
 

drizzle-orm/src/singlestore-core/dialect.ts

@@ -159,7 +159,9 @@ export class SingleStoreDialect {
 			columnNames.flatMap((colName, i) => {
 				const col = tableColumns[colName]!;
 
-				const onUpdateFnResult = col.onUpdateFn?.();
+				// Only invoke the `$onUpdate` callback when the column is absent
+				// from `set` — see drizzle-team/drizzle-orm#5780.
+				const onUpdateFnResult = set[colName] !== undefined ? undefined : col.onUpdateFn?.();
 				const value = set[colName]
 					?? (is(onUpdateFnResult, SQL)
 						? onUpdateFnResult

drizzle-orm/src/sqlite-core/dialect.ts

@@ -117,7 +117,9 @@ export abstract class SQLiteDialect {
 			columnNames.flatMap((colName, i) => {
 				const col = tableColumns[colName]!;
 
-				const onUpdateFnResult = col.onUpdateFn?.();
+				// Only invoke the `$onUpdate` callback when the column is absent
+				// from `set` — see drizzle-team/drizzle-orm#5780.
+				const onUpdateFnResult = set[colName] !== undefined ? undefined : col.onUpdateFn?.();
 				const value = set[colName]
 					?? (is(onUpdateFnResult, SQL)
 						? onUpdateFnResult

drizzle-orm/tests/on-update.test.ts

@@ -0,0 +1,70 @@
+import postgres from 'postgres';
+import { describe, expect, it } from 'vitest';
+import { pgTable, text, uuid } from '~/pg-core';
+import { drizzle } from '~/postgres-js';
+import { eq } from '~/sql';
+
+// Regression for drizzle-team/drizzle-orm#5780. In 0.45.x `buildUpdateSet`
+// invoked every column's `$onUpdate` callback eagerly, even when the column
+// value was explicitly supplied in `set`. Callbacks with side effects
+// (throwing, logging, reading external state) then ran on every UPDATE.
+//
+// These tests assert the 0.44.6 contract: `$onUpdate` is only invoked when
+// the column is absent from `set`. The pg-core dialect is exercised here;
+// the identical pattern lives in mysql-core, sqlite-core, singlestore-core,
+// and gel-core, and is fixed alongside pg-core in the same patch.
+
+const db = drizzle(postgres(''));
+
+describe('$onUpdate evaluation', () => {
+	it('does not invoke the callback when the column is explicitly provided in set', () => {
+		const table = pgTable('example', {
+			id: uuid('id').primaryKey(),
+			name: text('name').notNull(),
+			updatedById: uuid('updated_by_id')
+				.$onUpdate(() => {
+					throw new Error('should not be called when column is explicitly set');
+				})
+				.notNull(),
+		});
+
+		const query = db
+			.update(table)
+			.set({ name: 'foo', updatedById: '00000000-0000-0000-0000-000000000000' })
+			.where(eq(table.id, '00000000-0000-0000-0000-000000000000'));
+
+		expect(() => query.toSQL()).not.toThrow();
+		expect(query.toSQL()).toEqual({
+			sql:
+				'update "example" set "name" = $1, "updated_by_id" = $2 where "example"."id" = $3',
+			params: [
+				'foo',
+				'00000000-0000-0000-0000-000000000000',
+				'00000000-0000-0000-0000-000000000000',
+			],
+		});
+	});
+
+	it('invokes the callback exactly once when the column is absent from set', () => {
+		let invocations = 0;
+		const table = pgTable('example', {
+			id: uuid('id').primaryKey(),
+			name: text('name').notNull(),
+			updatedById: uuid('updated_by_id')
+				.$onUpdate(() => {
+					invocations++;
+					return '11111111-1111-1111-1111-111111111111';
+				})
+				.notNull(),
+		});
+
+		const query = db
+			.update(table)
+			.set({ name: 'foo' })
+			.where(eq(table.id, '00000000-0000-0000-0000-000000000000'));
+
+		const compiled = query.toSQL();
+		expect(invocations).toBe(1);
+		expect(compiled.params).toContain('11111111-1111-1111-1111-111111111111');
+	});
+});