🧪 @kaapi/validator-valibot

Valibot-powered validation plugin for Kaapi. Validate request params, payload, query, headers, and state using Valibot schemas. Includes built-in documentation helpers for seamless API docs generation.

🚀 Installation

npm install @kaapi/validator-valibot

📦 Peer Dependency

Requires Valibot:

npm install valibot@^1.1.0

🛠️ Usage

🔌 Register the Plugin

import { Kaapi } from '@kaapi/kaapi'
import { validatorValibot } from '@kaapi/validator-valibot'

const app = new Kaapi({
  port: 3000,
  host: 'localhost',
  docs: {
    disabled: false // explicitly enables documentation generation
  }
});

await app.extend(validatorValibot); // register the plugin

📐 Define a Schema

import * as v from 'valibot'
import { ValidatorValibotSchema } from '@kaapi/validator-valibot'

const routeSchema: ValidatorValibotSchema = {
  payload: v.object({
    name: v.string()
  })
}

🧭 Create a Route

app.base().valibot(routeSchema).route(
  {
    method: 'POST',
    path: '/items'
  },
  req => ({ id: Date.now(), name: req.payload.name })
)

// or using inline handler
/*
app.base().valibot(routeSchema).route({
  method: 'POST',
  path: '/items',
  handler: req => ({ id: Date.now(), name: req.payload.name })
})
*/

🧱 Build Routes Separately with withSchema

You can use withSchema to create validated routes without directly chaining from app.base(). This cleanly separates route construction from app registration.

import { withSchema } from '@kaapi/validator-valibot'
import * as v from 'valibot'

const schema = {
  payload: v.object({
    name: v.string()
  })
}

const route = withSchema(schema).route({
  method: 'POST',
  path: '/items',
  handler: req => ({ id: Date.now(), name: req.payload.name })
})

// later, during app setup
app.route(route)

This is the most flexible and convenient way to use @kaapi/validator-valibot when building modular APIs.

⚙️ Advanced Configuration

🔧 options

Customize Valibot parsing behavior:

| Property | Type | Default | Description | |---------------|---------------------------|-------------|-----------------------------------------------------------------------------| | abortEarly | boolean | undefined | Whether it should be aborted early | | abortPipeEarly | boolean | undefined | Whether a pipe should be aborted early | | lang | string | undefined | The selected language | | message | ErrorMessage<TIssue> | undefined | The error message |

🚨 failAction

Control how validation failures are handled:

| Value | Behavior | Safe? | Description | |---------------|------------------------------|-------|--------------------------------------------------| | 'error' | Reject with validation error | ✅ | Default safe behavior | | 'log' | Log and reject | ✅ | Useful for observability | | function | Custom handler | ✅ (developer-controlled) | Must return or throw explicitly | | 'ignore' | ❌ Not supported | ❌ | Unsafe and not implemented |

🧪 Example with Overrides

You can override Valibot validation behavior globally for all routes, or per route as needed.

🔁 Global Override (All Routes)

const app = new Kaapi({
  // ...
  routes: {
    plugins: {
      valibot: {
        options: {
          abortEarly: true
        },
        failAction: 'log'
      }
    }
  }
});

await app.extend(validatorValibot);

This sets abortEarly to true for all Valibot-validated routes, and logs validation errors before throwing them.

🔂 Per-Route Override

app.base().valibot({
  query: v.object({
    name: v.optional(v.pipe(v.string(), v.trim(), v.nonEmpty(), v.maxLength(10), v.description('Optional name to personalize the greeting response')), 'World'),
    age: v.optional(
      v.pipe(
        v.string(), 
        v.transform((input) => typeof input === 'string' ? Number(input) : input), 
        v.number(), 
        v.integer(), 
        v.minValue(1)
      )
    )
  }),
  options: {
    abortEarly: false
  },
  failAction: async (request, h, err) => {
    if (Boom.isBoom(err)) {
      return h.response({
        ...err.output.payload,
        details: err.data.validationError.issues
      }).code(err.output.statusCode).takeover()
    }
    return err
  }
}).route({
  path: '/greetings',
  method: 'GET',
  handler: ({ query: { name } }) => `Hello ${name}!`
});

📤 File Upload Example

Multipart file uploads with Valibot validation is supported. Here's how to validate an uploaded image file and stream it back in the response:

app.base().valibot({
  payload: v.object({
    file: v.pipe(
      v.looseObject({
        _data: v.instance(Buffer),
        hapi: v.looseObject({
          filename: v.string(),
          headers: v.looseObject({
            'content-type': v.picklist(['image/jpeg', 'image/jpg', 'image/png'] as const)
          })
        })
      }),
      v.description('The image to upload')
    )
  })
}).route({
  method: 'POST',
  path: '/upload-image',
  options: {
    description: 'Upload an image',
    payload: {
      output: 'stream',
      parse: true,
      allow: 'multipart/form-data',
      multipart: { output: 'stream' },
      maxBytes: 1024 * 3_000
    }
  }
}, (req, h) =>
  h.response(req.payload.file._data)
    .type(req.payload.file.hapi.headers['content-type'])
);

🧾 Notes

• looseObject is used to accommodate the structure of multipart file metadata.
• The _data: instanceof(Buffer) field is automatically interpreted as a binary field by the documentation generator.
• This ensures correct OpenAPI and Postman documentation is generated, with the file field shown as a binary upload.
• The route streams the uploaded image back with its original content type.

🔄 Flexible API Design

Prefer Joi or migrating gradually? No problem.

You can still use app.route(...) with Joi-based validation while adopting Valibot via app.base().valibot(...).route(...). This dual-mode support ensures graceful evolution, allowing traditional and modern routes to coexist without breaking changes.

📚 License

MIT

This package is tested as part of the Kaapi monorepo. See the main Kaapi README for coverage details.

🤝 Contributing

Contributions, issues, and feature requests are welcome! Feel free to open a discussion or submit a pull request.