## 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