Added very nice DataGrid control

UserService.DatabaseLayer/Repository/OrganizationUnitsRepository.cs

@@ -0,0 +1,50 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Linq.Expressions;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.EntityFrameworkCore;
+using UserService.DatabaseLayer.DataModels;
+
+namespace UserService.DatabaseLayer.Repository
+{
+    public class OrganizationUnitsRepository : BaseRepository<OrganizationUnit>, IOrganizationUnitsRepository
+    {
+        public OrganizationUnitsRepository() : base(x => x.OrganizationUnits)
+        {
+        }
+
+        /// <inheritdoc cref="GetAllAsync" />
+        public override async Task<IReadOnlyList<OrganizationUnit>> GetAllAsync(
+            Expression<Func<OrganizationUnit, bool>>? predicate = null, CancellationToken token = default)
+        {
+            await using var db = new UserServiceDbContext();
+            var result = new List<OrganizationUnit>();
+            var rootOus = await Context(db)
+                .Include(x => x.Parent)
+                .WhereOrDefault(predicate)
+                .ToListAsync(cancellationToken: token);
+
+            IEnumerable<OrganizationUnit> Rec(Node node)
+            {
+                if (!(node is OrganizationUnit organizationUnit)) yield break;
+                yield return organizationUnit;
+                foreach (var ouChild in rootOus.Where(x => x.ParentId != null && x.ParentId == organizationUnit.Id))
+                {
+                    foreach (var unit in Rec(ouChild))
+                    {
+                        yield return unit;
+                    }
+                }
+            }
+
+            foreach (var ou in rootOus.Where(x => x.ParentId is null))
+            {
+                result.AddRange(Rec(ou));
+            }
+
+            return result;
+        }
+    }
+}