useDefault option not working

[frrodriguez]

What version of Ajv are you using? Does the issue happen if you use the latest version?
8.11.0
Ajv options object

{
  useDefaults: "empty", // 'empty' or true
  allErrors: true,
  coerceTypes: true,
  parseDate: true,
}

JSON Schema

{
    "type": "object",
    "properties": {
      "disabled": {
        "type": "boolean",
        "default": false,
        "description": "Disable real redis connection for use a mock"
      },
      "clientOptions": {
        "type": "object",
        "properties": {
          "host": { "type": "string", "default": "localhost" },
          "port": { "type": "number" },
          "auth_pass": { "type": "string" }
        },
        "required": ["host"],
        "description": "Client options for redis connection"
      }
    },
    "oneOf": [
      { "properties": { "disabled": { "const": true } } },
      { "required": ["clientOptions"] }
    ],
    "required": ["disabled"]
  }

Sample data

Sample 1 (OK, just for test)

{ "disabled": false }

Sample 2 (ISSUED)

{  }

Your code

const Ajv = require("ajv");

const validator = new Ajv(options);

// Validation 1
const result1 = validator.validate(schema, data1); // (SAMPLE 1) Expected false and its ok

// Validation 2 Here its the problem
const result2 = validator.validate(schema, data2); // (SAMPLE 2) Expected false but returns true ??

Validation result, data AFTER validation, error messages

SAMPLE 1 OK!
// valid: false
[
  {
    instancePath: '/disabled',
    schemaPath: '#/oneOf/0/properties/disabled/const',
    keyword: 'const',
    params: { allowedValue: true },
    message: 'must be equal to constant'
  },
  {
    instancePath: '',
    schemaPath: '#/oneOf/1/required',
    keyword: 'required',
    params: { missingProperty: 'clientOptions' },
    message: "must have required property 'clientOptions'"
  },
  {
    instancePath: '',
    schemaPath: '#/oneOf',
    keyword: 'oneOf',
    params: { passingSchemas: null },
    message: 'must match exactly one schema in oneOf'
  }
]

SAMPLE 2 UNEXPECTED!!
// valid: true
nulll

What results did you expect?
With the useDefault property specified, i expect the behaviour for Sample1 and Sample2 would be the same and both fails cause takes the same false value <failing schema cause clientOptions its required by oneOf>
Expect same result when disabled its false (Sample1 its explicit and Sample2 its by default)

Are you going to resolve the issue?
Not sure

[epoberezkin]

it might be because of the order of validation, you might workaround by putting properties and oneOf in the different branches of allOf to ensure a specific validation order. Or you can put default in the same branch of oneOf that validates the property.