Configuration

Sometimes you need to define some configuration for a specific route, such as a middleware or a validation schema. For that, you can use the this: Use parameter.

The Use parameter is a type that receives one or multiple RouteMappers and returns the same configuration with the modifications made.

All route mappers must be exported within the route file itself so that it can be accessed by Kita later.

src/routes/index.ts

import type { RouteMapper, Use } from '@kitajs/runtime';

export function get(this: Use<typeof config>) {
  return true;
}

export const config: RouteMapper = (config) => {
  config.bodyLimit = 1024 * 1024 * 1024;
  return config;
};

The example above would be the same as defining the configuration directly on a pure Fastify instance.

app.route({
  url: '/',
  method: 'GET',
  bodyLimit: 1024 * 1024 * 1024,
  async handler(req, res) {
    return true;
  }
});

Using Multiple Configurations

You can use multiple RouteMappers to define different configurations.

The execution order will be the same as the order of definition within the Use array.

src/routes/index.ts

import type { RouteMapper, Use } from '@kitajs/runtime';

export function get(this: Use<[typeof config1, typeof config2]>) {
  return true;
}

export const config1: RouteMapper = (config) => {
  config.bodyLimit = 1024 * 1024 * 1024;
  return config;
};

export const config2: RouteMapper = (config) => {
  config.prefixTrailingSlash = 'both';
  return config;
};

Reusing Configurations

There’s no rule about defining the configuration function within the same route file. You can export the configuration function and reuse it in other routes.

src/routes/index.ts

src/routes/index.ts

import type { Use } from '@kitajs/runtime';
import { config } from '../config';

export function get(this: Use<typeof config>) {
  return true;
}

// You still need to export the config function
export { config } from '../config';