ajv-validator/ajv

report all duplicates with uniqueItems: "all" option

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#1092 opened on Sep 25, 2019

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 (6 comments) (0 reactions) (0 assignees)TypeScript (12,984 stars) (897 forks)batch import
enhancementhelp wanted

Description

I have an array of simple scalar values and I want validation to fail when there is a duplicate.

This works, however I want to be able to see all duplicates at once and not resolve them one at a time.

So I added the allErrors option into the solution and I still only see a single error.

Code to reproduce:

var Ajv = require('ajv')

var ajv = new Ajv({ allErrors: true, uniqueItems: true });
var schema = {
  "type": "array",
  "items": [
    { "type": "number" }
  ],
  "uniqueItems": true
}

var data = [1, 1, 2, 3, 3];

var validate = ajv.compile(schema);

console.log(validate.errors);

Result:

[ { keyword: 'uniqueItems',
    dataPath: '',
    schemaPath: '#/uniqueItems',
    params: { i: 4, j: 3 },
    message:
     'should NOT have duplicate items (items ## 3 and 4 are identical)' } ]

From the docs: allErrors: check all rules collecting all errors. Default is to return after the first error.

Contributor guide

Tech stack
javascripttypescriptnodejs
Domain
developer experiencetooling
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
JavaScriptNode.jsAjv basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70
Research direction
The issue requests that when allErrors is true, uniqueItems validation reports all duplicate items instead of stopping after the first. To implement, locate the uniqueItems validation logic in Ajv's source (likely in lib/validate.js or lib/keyword/uniqueItems.js). The current implementation returns early on first duplicate; modify it to collect all duplicates when allErrors is enabled. Check existing tests and ensure backward compatibility. No linked PRs or assignees indicate this is available.