Добавил свойство IsDeleted в модель Phone. Создал миграцию. Поменял выборку из БД в экшене Index

Lesson49/Controllers/PhonesController.cs

@@ -22,7 +22,7 @@ namespace Lesson49.Controllers
         public IActionResult Index(string searchString) //Phones/Create
         {
             List<Phone> phones = _db.Phones
-                .Include(p => p.Brand)
+                .Include(p => p.Brand).Where(p => p.IsDeleted == false)
                 .ToList();
             if (!string.IsNullOrEmpty(searchString))
                 phones = phones.Where(p => p.Name.Contains(searchString, StringComparison.OrdinalIgnoreCase)).ToList();
@@ -66,7 +66,8 @@ namespace Lesson49.Controllers
             Phone phone = _db.Phones.FirstOrDefault(p => p.Id == id);
             if (phone != null)
             {
-                _db.Phones.Remove(phone);
+                phone.IsDeleted = true;
+                _db.Phones.Update(phone);
                 _db.SaveChanges();
                 return RedirectToAction("Index");
             }

Lesson49/Migrations/20210331141323_AddIsDeletedFieldInPhones.Designer.cs

+// <auto-generated />
+using Lesson49.Models.Data;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+
+namespace Lesson49.Migrations
+{
+    [DbContext(typeof(MobileContext))]
+    [Migration("20210331141323_AddIsDeletedFieldInPhones")]
+    partial class AddIsDeletedFieldInPhones
+    {
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder
+                .HasAnnotation("ProductVersion", "3.1.13");
+
+            modelBuilder.Entity("Lesson49.Models.Brand", b =>
+                {
+                    b.Property<int>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER");
+
+                    b.Property<bool>("IsActive")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<string>("Name")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("WebSite")
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("Id");
+
+                    b.ToTable("Brands");
+                });
+
+            modelBuilder.Entity("Lesson49.Models.Order", b =>
+                {
+                    b.Property<int>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER");
+
+                    b.Property<string>("Address")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("ContactPhone")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Name")
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("PhoneId")
+                        .HasColumnType("INTEGER");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("PhoneId");
+
+                    b.ToTable("Orders");
+                });
+
+            modelBuilder.Entity("Lesson49.Models.Phone", b =>
+                {
+                    b.Property<int>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER");
+
+                    b.Property<int>("BrandId")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<bool>("IsDeleted")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<string>("Name")
+                        .HasColumnType("TEXT");
+
+                    b.Property<double>("Price")
+                        .HasColumnType("REAL");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("BrandId");
+
+                    b.ToTable("Phones");
+                });
+
+            modelBuilder.Entity("Lesson49.Models.Order", b =>
+                {
+                    b.HasOne("Lesson49.Models.Phone", "Phone")
+                        .WithMany()
+                        .HasForeignKey("PhoneId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+                });
+
+            modelBuilder.Entity("Lesson49.Models.Phone", b =>
+                {
+                    b.HasOne("Lesson49.Models.Brand", "Brand")
+                        .WithMany()
+                        .HasForeignKey("BrandId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}

Lesson49/Migrations/20210331141323_AddIsDeletedFieldInPhones.cs

+using Microsoft.EntityFrameworkCore.Migrations;
+
+namespace Lesson49.Migrations
+{
+    public partial class AddIsDeletedFieldInPhones : Migration
+    {
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<bool>(
+                name: "IsDeleted",
+                table: "Phones",
+                nullable: false,
+                defaultValue: false);
+        }
+
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "IsDeleted",
+                table: "Phones");
+        }
+    }
+}

Lesson49/Migrations/MobileContextModelSnapshot.cs

@@ -69,6 +69,9 @@ namespace Lesson49.Migrations
                     b.Property<int>("BrandId")
                         .HasColumnType("INTEGER");
 
+                    b.Property<bool>("IsDeleted")
+                        .HasColumnType("INTEGER");
+
                     b.Property<string>("Name")
                         .HasColumnType("TEXT");
 

Lesson49/Models/Phone.cs

@@ -8,5 +8,7 @@
         public int BrandId { get; set; }
         public Brand Brand { get; set; }
         public double Price { get; set; }
+
+        public bool IsDeleted { get; set; }
     }
 }
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