Response Validation Plugin

Response Validation Plugin validates server responses against your contract before your application uses them. This helps ensure the data returned by the server matches the types defined in your contract.

Setup

import { ResponseValidationLinkPlugin } from '@orpc/contract/plugins'

const link = new RPCLink({
  plugins: [
    new ResponseValidationLinkPlugin(contract),
  ],
})

INFO

If you do not have a contract, you can use a unlazied router instead.

INFO

The link can be any supported oRPC link, such as RPCLink, OpenAPILink, or a custom one.

Limitations

Schemas that transform values into a different type are not supported.

Why? Consider this schema, which accepts a number and transforms it into a string:

const unsupported = z.number().transform(value => value.toString())

When the server validates the output, it transforms the number into a string. The client then receives that string, but the schema still expects a number as input, so validation fails.

Typesafe Errors Compatibility

This plugin reconciles ORPC errors from other interceptors and plugins, allowing you to use ORPCError for typesafe errors.

Custom Validation Errors

If you have already customized validation errors on the server, you can use interceptors to catch and map the validation errors thrown by this plugin so they match your server-side errors.

import { ORPCError } from '@orpc/client'
import { ValidationError } from '@orpc/contract'

const link = new RPCLink({
  plugins: [
    new ResponseValidationLinkPlugin(contract),
  ],
  interceptors: [
    async ({ next }) => {
      try {
        return await next()
      }
      catch (error) {
        if (
          error instanceof ORPCError
          && error.code === 'INTERNAL_SERVER_ERROR'
          && error.cause instanceof ValidationError
        ) {
          throw new CustomOutputValidationError(error.cause.issues)
        }

        throw error
      }
    }
  ]
})

Advanced Usage

You can also use this plugin in guides such as Expanding Type Support for OpenAPI Link.

Learn More

For implementation details, see the source code.