## Runtime Validation
Deserialize validates the input data and throws descriptive errors:
<InteractiveMacro
code={`/** @derive(Deserialize) */
class User {
name: string;
email: string;
}`} />
```typescript
// Missing required field
User.fromJSON({ name: 'Alice' });
// Error: User.fromJSON: missing required field "email"
// Wrong type
User.fromJSON('not an object');
// Error: User.fromJSON: expected an object, got string
// Array instead of object
User.fromJSON([1, 2, 3]);
// Error: User.fromJSON: expected an object, got array
```
## Automatic Type Conversion
Deserialize automatically converts JSON types to their TypeScript equivalents:
| string/number/boolean | `string`/`number`/`boolean` | Direct assignment
| ISO string | `Date` | `new Date(string)`
| array | `T[]` | Maps items with auto-detection
| object | `Map<K, V>` | `new Map(Object.entries())`
| array | `Set<T>` | `new Set(array)`
| object | Nested class | Calls `fromJSON()` if available
