# Class Validator Schema (/framework/schema/class-validator)

Integrate Class Validator with your notification workflows

Novu Framework allows you to use [Class Validator](https://www.npmjs.com/package/class-validator) to define the [Control](/framework/controls) and [Payload](/framework/payload) schemas for your workflows.

## Add class validator to your project

<Steps>
  <Step title="Install Class Validator Packages">
    ```bash
    npm install class-validator class-validator-jsonschema reflect-metadata
    ```

    Novu requires the `class-validator-jsonschema` package to generate JSON schemas from your DTOs. You may also need the `reflect-metadata` package.
  </Step>

  <Step title="Use Class Validator in your workflow">
    After installation, the Class Validator DTOs can be used interchangeably with the `controlSchema` and `payloadSchema` options in your workflow definitions.

    ```tsx
    import { workflow } from '@novu/framework';
    import { IsString, IsBoolean, IsNotEmpty, IsOptional, Type, NestedValidation } from "class-validator";

    class TestComponent {
        @IsString()
        subject: string;

        @IsString()
        content: string;
    }

    class TestControlSchema {
        @IsBoolean()
        hideBanner: boolean;

        @IsString()
        @IsNotEmpty()
        @IsOptional()
        subject?: string;

        // Allowing no code control over the component in the Dashboard UI
        @Type(() => NewSignUpComponent)
        @NestedValidation({ each: true })
        @IsOptional()
        components?: NewSignUpComponent[];
    }

    class TestPayloadSchema {
        @IsString()
        username: string;
    }

    export const testWorkflow = workflow('test-workflow', async ({ step, payload }) => {
        await step.email('send-email', async (controls) => {
            return {
                subject: controls.subject,
                body: 'Hello, World!',
            };
        },
        {
            controlSchema: TestControlSchema,
        });
    }, {
        payloadSchema: TestPayloadSchema,
    });
    ```
  </Step>
</Steps>

## Controls and Payload UI

When you define a `controlSchema` for a step, Novu will automatically generate a UI for the controls in the workflow editor.

* **Form Input Title** - Will be derived from the key of the Class Validator schema. Unfortunately Class Validator does not support custom titles at this point.
* **Form Input Type** - Will be derived from the Class Validator schema type, with support for `string`, `number`, `boolean`, and `enum` and `array` types.
* **Default Value** - Unfortunately Class Validator does not support default values at this point.
* **Validation** - Will be derived from the Class Validator schema validation decorators, including `@Min`, `@Max`, `@IsEmail`, `@IsUrl` and etc...