> For the complete documentation index, see [llms.txt](https://marblejs.gitbook.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://marblejs.gitbook.io/docs/other/api-reference/middleware-joi.md).

# @marblejs-contrib/middleware-joi

<div align="center"><img src="/files/-LLYJsPvN01UHocjSg46" alt=""></div>

[Joi](https://github.com/hapijs/joi) is an object schema description language and validator for JavaScript objects. Using its schema language, you can validate things like:

* HTTP request headers
* HTTP body parameters
* HTTP request query parameters
* URL parameters

You can find detailed API reference for Joi schemas [here](https://github.com/hapijs/joi/blob/v13.6.0/API.md).

{% hint style="warning" %}
**Deprecation warning**

Since version 4.0 `@marblejs-contrib/middleware-joi` package is deprecated and won't be maintained anymore.
{% endhint %}

{% hint style="warning" %}
Since version 4.0, the middleware is a part of contrib packages. If you really want to use this middleware you can reach it via `@marblejs-contrib/middleware-joi`.
{% endhint %}

{% hint style="warning" %}
For more advanced request or event validation purposes we highly recommend to use [@marblejs/middleware-io](/docs/other/api-reference/middleware-io.md) package instead. It can better handle type inference for complex schemas.
{% endhint %}

### Installation

```bash
yarn add @marblejs-contrib/middleware-joi
```

Requires `@marblejs/core` to be installed.

### Importing

```typescript
import { validator$ } from '@marblejs-contrib/middleware-joi';
```

### Type declaration

```
validator$ :: (Schema, Joi.ValidationOptions) -> HttpMiddlewareEffect
```

### **Parameters**

| *parameter* | definition                                                                                                            |
| ----------- | --------------------------------------------------------------------------------------------------------------------- |
| *schema*    | `Schema`                                                                                                              |
| *options*   | \<optional> `Joi.ValidationOptions` (see: [Joi API reference](https://github.com/hapijs/joi/blob/v13.6.0/API.md#joi)) |

#### ***Schema***

| *parameter* | definition        |
| ----------- | ----------------- |
| *headers*   | \<optional> `any` |
| *params*    | \<optional> `any` |
| *query*     | \<optional> `any` |
| *body*      | \<optional> `any` |

### Usage

**1.** Example of using middleware on a *GET* route to validate query parameters:

{% code title="foo.effect.ts" %}

```typescript
import { r } from '@marblejs/http';
import { validator$, Joi } from '@marblejs-contrib/middleware-joi';

const foo$ = r.pipe(
  r.matchPath('/'),
  r.matchType('GET'),
  r.useEffect(req$ => req$.pipe(
    use(validator$({
      query: Joi.object({
        id: Joi.number().min(1).max(10),
      })
    }));
    // ...
  )));
```

{% endcode %}

Example above will validate each incoming request connected with `foo$` *Effect*. The validation blueprint defines that the `id` query parameter should be a number between *<1..10>*. If the schema requirements are not satisfied the middleware will throw an error with description what went wrong.

```typescript
{
  error: {
    status: 400,
    message: '"id" is required'
  }
}
```

**2.** Example of validating all incoming requests:

{% code title="app.ts" %}

```typescript
import { validator$, Joi } from '@marblejs-contrib/middleware-joi';

const middlewares = [
  // ...
  validator$(
    {
      headers: Joi.object({
        token: Joi.string().token().required(),
        accept: Joi.string().default('application/json')
      })
    },
    { stripUnknown: true },
  )
];

const effects = [
  endpoint1$,
  endpoint2$,
  ...
];

const app = httpListener({ middlewares, effects });
```

{% endcode %}

### Credits

Middleware author: [Lucio Rubens](https://github.com/luciorubeens)