# Effect

Generate [Effect Schema](https://effect.website/docs/schema/introduction/) schemas from your OpenAPI specification for runtime validation.

## Configuration

Set the `client` option to `effect`:

```ts
import { defineConfig } from 'orval';

export default defineConfig({
  petstore: {
    output: {
      client: 'effect',
      mode: 'single',
      target: './src/api/schemas',
    },
    input: {
      target: './petstore.yaml',
    },
  },
});
```

## Generated Output

Orval generates an Effect schema for each model in your OpenAPI specification:

```ts
import { Schema as S } from 'effect';

export const CreatePetsBody = S.Struct({
  id: S.Number,
  name: S.String,
  tag: S.optional(S.String),
});
```

## Usage

### Decoding Data

```ts
import { Schema as S } from 'effect';
import { CreatePetsBody } from './src/api/schemas';

const pet = { id: 1, name: 'Buddy', tag: 'dog' };
const parsedPet = S.decodeUnknownSync(CreatePetsBody)(pet);
// => { id: 1, name: "Buddy", tag: "dog" }
```

### Type Inference

```ts
import { Schema as S } from 'effect';
import { CreatePetsBody } from './src/api/schemas';

type Pet = S.Schema.Type<typeof CreatePetsBody>;

const pet: Pet = { id: 1, name: 'Buddy', tag: 'dog' };
```

### Safe Decoding

```ts
import { Schema as S } from 'effect';
import { Either } from 'effect';

const result = S.decodeUnknownEither(CreatePetsBody)(unknownData);

if (Either.isRight(result)) {
  console.log(result.right);
} else {
  console.error(result.left);
}
```

## Combining with HTTP Clients

See the [Client with Effect](/docs/guides/client-with-effect) guide for using Effect schemas with React Query, SWR, or other HTTP clients.