fix: invalid parsing body with missed fields if used object model (#1003)

Author: ilyhalight

src/compose.ts

@@ -1421,11 +1421,16 @@ export const composeHandler = ({
 				fnLiteral += `const isNotEmptyObject=c.body&&(typeof c.body==="object"&&isNotEmpty(c.body))\n`
 
 			if (hasProperty('default', validator.body)) {
+				// @ts-expect-error private property
+				const schema = validator.body.schema
 				const value = Value.Default(
-					// @ts-expect-error private property
-					validator.body.schema,
-					// @ts-expect-error private property
-					validator.body.schema.type === 'object' ? {} : undefined
+					schema,
+					schema.type === 'object' ||
+						(schema[TypeBoxSymbol.kind] === 'Import' &&
+							schema.$defs[schema.$ref][TypeBoxSymbol.kind] ===
+								'Object')
+						? {}
+						: undefined
 				)
 
 				const parsed =

test/validator/body.test.ts

@@ -795,4 +795,25 @@ describe('Body Validator', () => {
 
 		expect(response).toEqual({ field: { decoded: 'bar' }, foo: 'test' })
 	})
+
+	it('right rejects missed field with model', async () => {
+		const model = new Elysia().model(
+			'user',
+			t.Object({
+				username: t.String(),
+				age: t.Integer()
+			})
+		)
+
+		const app = new Elysia().use(model).post('/', ({ body }) => body, {
+			body: 'user'
+		})
+		const res = await app.handle(
+			post('/', {
+				name: 'sucrose'
+			})
+		)
+
+		expect(res.status).toBe(422)
+	})
 })