Umbraco-CMS/src/Umbraco.Web.BackOffice/Controllers/RelationController.cs

using Microsoft.AspNetCore.Authorization;
using Umbraco.Cms.Core;
using Umbraco.Cms.Core.Mapping;
using Umbraco.Cms.Core.Models;
using Umbraco.Cms.Core.Models.ContentEditing;
using Umbraco.Cms.Core.Services;
using Umbraco.Cms.Web.Common.Attributes;
using Umbraco.Cms.Web.Common.Authorization;
using Umbraco.Extensions;

namespace Umbraco.Cms.Web.BackOffice.Controllers;

[PluginController(Constants.Web.Mvc.BackOfficeApiArea)]
[Authorize(Policy = AuthorizationPolicies.SectionAccessContent)]
public class RelationController : UmbracoAuthorizedJsonController
{
    private readonly IRelationService _relationService;
    private readonly IUmbracoMapper _umbracoMapper;

    public RelationController(IUmbracoMapper umbracoMapper, IRelationService relationService)
    {
        _umbracoMapper = umbracoMapper ?? throw new ArgumentNullException(nameof(umbracoMapper));
        _relationService = relationService ?? throw new ArgumentNullException(nameof(relationService));
    }

    public RelationDisplay? GetById(int id) =>
        _umbracoMapper.Map<IRelation, RelationDisplay>(_relationService.GetById(id));

    //[EnsureUserPermissionForContent("childId")]
    public IEnumerable<RelationDisplay> GetByChildId(int childId, string relationTypeAlias = "")
    {
        IRelation[] relations = _relationService.GetByChildId(childId).ToArray();

        if (relations.Any() == false)
        {
            return Enumerable.Empty<RelationDisplay>();
        }

        if (string.IsNullOrWhiteSpace(relationTypeAlias) == false)
        {
            return
                _umbracoMapper.MapEnumerable<IRelation, RelationDisplay>(
                    relations.Where(x => x.RelationType.Alias.InvariantEquals(relationTypeAlias))).WhereNotNull();
        }

        return _umbracoMapper.MapEnumerable<IRelation, RelationDisplay>(relations).WhereNotNull();
    }
}