Fastify ValidationResult type and AJV v8 ErrorObject mismatch

[avin-kavish]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Fastify version

4

Plugin version

No response

Node.js version

16

Operating system

Linux

Operating system version (i.e. 20.04, 11.3, 10)

20

Description

AJV error object is like this,

export interface ErrorObject<K extends string = string, P = Record<string, any>, S = unknown> {
  keyword: K
  instancePath: string
  schemaPath: string
  params: P
  // Added to validation errors of "propertyNames" keyword schema
  propertyName?: string
  // Excluded if option `messages` set to false.
  message?: string
  // These are added with the `verbose` option.
  schema?: S
  parentSchema?: AnySchemaObject
  data?: unknown
}

Fastify type is like this,

export interface ValidationResult {
  keyword: string;
  dataPath: string;
  schemaPath: string;
  params: Record<string, string | string[]>;
  message: string;
}

In version 3 of Fastify (and the AJV version it used), AJV errors were directly assignable to ValidationResult type and vice verca.
But in v4 the types mismatch. looks like AJV no longer has the dataPath key. It was changed here.

Steps to Reproduce

Try this in v3 and v4 projects.

import { ValidationResult } from 'fastify'
import { ErrorObject } from 'ajv'

const foo = {} as ErrorObject

const bar = {} as ValidationResult

const baz: ErrorObject = bar

const bass: ValidationResult = foo

Expected Behavior

Edit:
Maybe fastify is internally converting the ErrorObject to a ValidationError. In that case, it wouldn't be an issuue. But it maybe the case that, fastify is not handling this new ErrorObject properly.

[mcollina]

Thanks for reporting! Would you like to send a Pull Request to address this issue? Remember to add unit tests.

[avin-kavish]

Adding more info for whoever picks this up, in lib/context.js it looks like defaultSchemaErrorFormatter is using instancePath so it's the type defs that are outdated.

[alex-laz]

Pull request: #4066