Unique validation for custom defined fields in an array property for json-editor

json-editor-unique-array-properties.js

JSONEditor.defaults.custom_validators.push(function(schema, value, path) {
    let errors = [];

    if (schema.type !== 'object') {
        return errors;
    }

    let property = '';
    let uniqueValues = [];
    let uniqueFieldsStr = '';

    Object.keys(schema.properties).forEach(function (propKey) {
        property = propKey;
        path = 'root.' + property;
        const propObj = schema.properties[propKey];

        if (propObj.type !== 'array') {
            return;
        }

        if (!('uniqueFields' in propObj)) {
            return;
        }

        uniqueFieldsStr = propObj.uniqueFields.join(', ');

        if (!value[propKey].length) {
            return;
        }

        value[propKey].forEach(function(valueObj) {
            let fieldValueStr = '';
            Object.keys(valueObj).forEach(function (field) {
                if (propObj.uniqueFields.indexOf(field) > -1) {
                    fieldValueStr += valueObj[field];
                }
            });
            uniqueValues.push(fieldValueStr);
        });

    });

    if ((new Set(uniqueValues)).size !== uniqueValues.length) {
        errors.push({
            path: path,
            property: property,
            message: 'Value for ' + property + ' must be unique across ' + uniqueFieldsStr
        });
    }

    return errors;
});

To use it, just add "uniqueFields": ["field1", "field2"], to your array property in your schema.json