Preserve JSON expression casts in generated schemas

Author: joe-thom

drizzle-kit/src/introspect-pg.ts

@@ -775,6 +775,10 @@ const mapDefault = (
 	}
 
 	if (lowered.startsWith('jsonb')) {
+		if (isExpression) {
+			return `.default(${mapColumnDefault(defaultValue, true)})`;
+		}
+
 		const def = typeof defaultValue !== 'undefined'
 			? defaultValue.replace(/::(.*?)(?<![^\w"])(?=$)/, '').slice(1, -1)
 			: null;
@@ -783,6 +787,10 @@ const mapDefault = (
 	}
 
 	if (lowered.startsWith('json')) {
+		if (isExpression) {
+			return `.default(${mapColumnDefault(defaultValue, true)})`;
+		}
+
 		const def = defaultValue ? defaultValue.replace(/::(.*?)(?<![^\w"])(?=$)/, '').slice(1, -1) : null;
 
 		return typeof defaultValue !== 'undefined' ? `.default(${def})` : '';

drizzle-kit/src/serializer/pgSerializer.ts

@@ -2038,6 +2038,7 @@ export const defaultForColumn = (column: any, internals: PgKitInternals, tableNa
 	) {
 		return undefined;
 	}
+	const originalColumnDefault = column.column_default.toString();
 
 	if (column.column_default.endsWith('[]')) {
 		column.column_default = column.column_default.slice(0, -2);
@@ -2099,7 +2100,7 @@ export const defaultForColumn = (column: any, internals: PgKitInternals, tableNa
 				internals!.tables![tableName]!.columns[columnName]!.isDefaultAnExpression = true;
 			}
 
-			return columnDefaultAsString;
+			return originalColumnDefault;
 		}
 
 		const jsonWithoutSpaces = JSON.stringify(JSON.parse(columnDefaultAsString.slice(1, -1)));

drizzle-kit/tests/pg-json-defaults.test.ts

@@ -1,6 +1,8 @@
 import { expect, test } from 'vitest';
 import { introspectPgDB } from '../src/api';
 import type { DrizzlePgDB } from '../src/api';
+import { schemaToTypeScript } from '../src/introspect-pg';
+import { fromDatabase } from '../src/serializer/pgSerializer';
 
 const columnRow = {
 	table_name: 'items',
@@ -49,3 +51,11 @@ test('normalizes a quoted jsonb literal default', async () => {
 
 	expect(schema.tables['public.items']!.columns.payload!.default).toBe(`'{"kind":"record"}'::jsonb`);
 });
+
+test('preserves casts and generates SQL for jsonb expression defaults', async () => {
+	const expression = "current_setting('app.payload')::jsonb";
+	const schema = await fromDatabase(databaseWithDefault(expression), () => true, ['public']);
+
+	expect(schema.tables['public.items']!.columns.payload!.default).toBe(expression);
+	expect(schemaToTypeScript(schema, 'preserve').file).toContain(`.default(sql\`${expression}\`)`);
+});