removed unused imports; added someText check; fixed crud business null check

Luticate2.Utils/Business/LuCrudBusiness.cs

             if (newEntity)
             {
                 _notificationsBusiness.NotifyCreate(EntityType, newEntity.Data,
-                    s => NotifyCreateFilter(s, newEntity.Data));
+                    NotifyCreateFilter != null ? s => NotifyCreateFilter(s, newEntity.Data) : (Func<string, bool>) null);
                 return LuResult<T>.Ok(returnFunc(newEntity.Data));
             }
             return newEntity.To<T>();
             if (editedEntity)
             {
                 _notificationsBusiness.NotifyUpdate(EntityType, originalEntity.Data, editedEntity.Data,
-                    s => NotifyUpdateFilter(s, originalEntity.Data, editedEntity.Data));
+                    NotifyUpdateFilter != null ? s => NotifyUpdateFilter(s, originalEntity.Data, editedEntity.Data) : (Func<string, bool>) null);
                 return LuResult<T>.Ok(returnFunc(editedEntity.Data));
             }
             return editedEntity.To<T>();
             if (res)
             {
                 _notificationsBusiness.NotifyDelete(EntityType, originalEntity.Data,
-                    s => NotifyDeleteFilter(s, originalEntity.Data));
+                    NotifyDeleteFilter != null ? s => NotifyDeleteFilter(s, originalEntity.Data) : (Func<string, bool>) null);
             }
             return res;
         }

Luticate2.Utils/Controllers/LuController.cs

-using System;
-using System.Collections.Generic;
-using System.Threading;
-using Luticate2.Utils.Dbo;
+using System.Collections.Generic;
 using Luticate2.Utils.Dbo.Basic;
 using Luticate2.Utils.Dbo.Result;
 using Microsoft.AspNetCore.Mvc;
-//using Microsoft.AspNetCore.SignalR.Infrastructure;
 
 namespace Luticate2.Utils.Controllers
 {
     public abstract class LuController : Controller
     {
-//        protected IConnectionManager ConnectionManager { get; set; }
 
         protected IDictionary<object, object> LuItems => HttpContext.GetLuItems();
 

Luticate2.Utils/Controllers/LuCrudController.cs

-using System;
-using System.Linq;
-using Luticate2.Utils.Dbo;
-using Luticate2.Utils.Dbo.Basic;
+using Luticate2.Utils.Dbo.Basic;
 using Luticate2.Utils.Dbo.Filter;
 using Luticate2.Utils.Dbo.OrderBy;
 using Luticate2.Utils.Interfaces;

Luticate2.Utils/Controllers/LuResultException.cs

 using System;
-using Luticate2.Utils.Dbo;
 using Luticate2.Utils.Dbo.Result;
 
 namespace Luticate2.Utils.Controllers

Luticate2.Utils/DataAccess/LuEfCrudDataAccess.cs

 using Luticate2.Utils.Interfaces;
 using Luticate2.Utils.Utils;
 using Microsoft.EntityFrameworkCore;
-using Microsoft.EntityFrameworkCore.Metadata.Internal;
 
 namespace Luticate2.Utils.DataAccess
 {

Luticate2.Utils/DataAccess/LuEfDataAccess.cs

 using System;
 using System.Collections.Generic;
 using System.Linq.Expressions;
-using Luticate2.Utils.Dbo;
 using Luticate2.Utils.Dbo.Result;
 using Microsoft.EntityFrameworkCore;
 

Luticate2.Utils/Interfaces/ILuCrudInterface.cs

 using System;
 using System.Collections.Generic;
-using Luticate2.Utils.Dbo;
 using Luticate2.Utils.Dbo.Basic;
 using Luticate2.Utils.Dbo.Filter;
 using Luticate2.Utils.Dbo.OrderBy;

Luticate2.Utils/Middlewares/LuExceptionMiddleware.cs

 using System;
-using System.Buffers;
 using System.Threading.Tasks;
 using Luticate2.Utils.Controllers;
 using Luticate2.Utils.Dbo.Basic;
 using Microsoft.AspNetCore.Http;
-using Microsoft.AspNetCore.Mvc.Formatters;
-using Microsoft.AspNetCore.Mvc.Infrastructure;
 using Newtonsoft.Json;
 
 namespace Luticate2.Utils.Middlewares

TestUtils/DataAccess/LuUtilsPkGuidDataAccess.cs

 using System;
+using System.Linq;
 using System.Linq.Expressions;
 using Luticate2.Utils.DataAccess;
 using Luticate2.Utils.Dbo.Filter;
+using Luticate2.Utils.Dbo.Result;
 using TestUtils.DataAccess.Models;
 using TestUtils.Dbo.PkGuid;
 
         {
             return model => LuUtilsDbContext.lu_texts_match(filter.Query, model.some_text + " " + model.some_int.ToString());
         }
+
+        public LuResult<bool> SomeTextExists(string someText)
+        {
+            return Execute(() => LuResult<bool>.Ok(Table.Any(guid => guid.some_text == someText)));
+        }
     }
 }

WebApiUtils/Business/PkGuidBusiness.cs

 {
     public class PkGuidBusiness : LuCrudBusiness<LuUtilsPkGuidDataAccess, PkGuidAddDbo, PkGuidDbo, PkGuidAddDbo, string>
     {
+        private readonly LuUtilsPkGuidDataAccess _dataAccess;
 
         public PkGuidBusiness(LuUtilsPkGuidDataAccess dataAccess, LuNotificationsBusiness notificationsBusiness) : base(dataAccess, notificationsBusiness)
         {
+            _dataAccess = dataAccess;
             EntityType = "pkguid";
         }
 
+        public LuResult<bool> SomeTextExists(string someText)
+        {
+            return _dataAccess.SomeTextExists(someText);
+        }
+
         protected override LuResult<PkGuidAddDbo> CheckAdd(PkGuidAddDbo obj)
         {
+            var res = SomeTextExists(obj.SomeText);
+            if (!res)
+            {
+                return res.To<PkGuidAddDbo>();
+            }
+            if (res.Data)
+            {
+                return LuResult<PkGuidAddDbo>.Error(LuStatus.InputError, "someText already exists", "");
+            }
             if (obj.SomeText.EndsWith("_edited"))
             {
                 return LuResult<PkGuidAddDbo>.Error(LuStatus.InputError, "someText can not end with '_edited'", "");
 
         protected override LuResult<PkGuidAddDbo> CheckEdit(PkGuidDbo dbo, PkGuidAddDbo update)
         {
+            if (dbo.SomeText != update.SomeText)
+            {
+                var res = SomeTextExists(update.SomeText);
+                if (!res)
+                {
+                    return res.To<PkGuidAddDbo>();
+                }
+                if (res.Data)
+                {
+                    return LuResult<PkGuidAddDbo>.Error(LuStatus.InputError, "someText already exists", "");
+                }
+            }
             if (!update.SomeText.EndsWith("_edited"))
             {
                 return LuResult<PkGuidAddDbo>.Error(LuStatus.InputError, "someText must end with '_edited'", "");