How to check if a property has the same value as one of the other items in a object array with ajv?

Question

I'm trying to write a json schema for validating cross references using AJV and typescript.

Is there any way to check that a property contains another property from any item in the array (not a specific item in the array).

Also both the property to check and the 'source' property are in items inside object arrays.

For example:

import Ajv, { ValidateFunction } from "ajv";

const ajv = new Ajv({$data: true, strict: true});

const schema = {
    type: "object",
    properties: {
        things: {
            type: "array",
            items: {
                type: "object",
                properties: {
                    thing_name: {
                        type: "string"
                    }
                }
            }
        },
        other: {
            type: "string",
            enum: { $data: "0/i/dont/know/how/to/address/items/in/this"
        }
    }
}

const validData = {
    things: [
        { thing_name: "foo" },
        { thing_name: "bar" }
    ],
    other: "foo"
}

const invalidData = {
    things: [
        { thing_name: "foo" },
        { thing_name: "bar" }
    ],
    other: "baz"
}

const validator = ajv.compile(schema);

validator(validData) // true
validator(invalidData) // true, but should be false

Here both validations return true, but I could't make a valid json reference that also would validate properly.

I've tried using a enum field containing:

{ $data: "0/things/thing_name" }
{ $data: "0/things/0/thing_name" },
{ $data: "0/things/items/properties/thing_name/enum" }

But since when AJV cannot resolve the reference it always validates, it's difficult to understand what is going on under the hood.

Is there some way to do this, or do I need to implement a 'helper script'?

Answer 1

You can validate that things array contains an item with the value of other property. The "order" in which validation is describe is different, but eventually will give you the save validation result

const schema = {
    type: 'object',
    properties: {
        things: {
            type: "array",
            contains: { 
                type: "object",
                properties: {
                    thing_name: {
                        const: { $data: '/other'},
                    }
                }
            },
            items: {
                type: "object",
                properties: {
                    thing_name: {
                        type: "string"
                    }
                }
            }
        },
        other: {
            type: 'string',
        },
    },
};