Umbraco-CMS/src/Umbraco.Infrastructure/PropertyEditors/ValueListUniqueValueValidator.cs

// Copyright (c) Umbraco.
// See LICENSE for more details.

using System.ComponentModel.DataAnnotations;
using Newtonsoft.Json.Linq;
using Umbraco.Extensions;

namespace Umbraco.Cms.Core.PropertyEditors;

/// <summary>
///     Represents a validator which ensures that all values in the list are unique.
/// </summary>
public class ValueListUniqueValueValidator : IValueValidator
{
    public IEnumerable<ValidationResult> Validate(object? value, string? valueType, object? dataTypeConfiguration)
    {
        // the value we get should be a JArray
        // [ { "value": <value>, "sortOrder": 1 }, { ... }, ... ]
        if (!(value is JArray json))
        {
            yield break;
        }

        // we ensure that values are unique
        // (those are not empty - empty values are removed when persisting anyways)
        var groupedValues = json.OfType<JObject>()
            .Where(x => x["value"] != null)
            .Select((x, index) => new { value = x["value"]?.ToString(), index })
            .Where(x => x.value.IsNullOrWhiteSpace() == false)
            .GroupBy(x => x.value);

        foreach (var group in groupedValues.Where(x => x.Count() > 1))
        {
            yield return new ValidationResult($"The value \"{group.Last().value}\" must be unique", new[]
            {
                // use the index number as server field so it can be wired up to the view
                "item_" + group.Last().index.ToInvariantString(),
            });
        }
    }
}