Added better Insert skip check.

Author: sdanyliv

Source/LinqToDB.EntityFrameworkCore/EFCoreMetadataReader.cs

@@ -263,6 +263,17 @@ public T[] GetAttributes<T>(Type type, MemberInfo memberInfo, bool inherit = tru
 							}
 						}
 
+						var behaviour = prop.GetBeforeSaveBehavior();
+						var skipOnInsert = prop.ValueGenerated.HasFlag(ValueGenerated.OnAdd);
+
+						if (skipOnInsert)
+						{
+							skipOnInsert = isIdentity || behaviour != PropertySaveBehavior.Save;
+						}
+
+						var skipOnUpdate = behaviour != PropertySaveBehavior.Save ||
+						                   prop.ValueGenerated.HasFlag(ValueGenerated.OnUpdate);
+
 						return new T[]
 						{
 							(T)(Attribute)new ColumnAttribute
@@ -275,7 +286,9 @@ public T[] GetAttributes<T>(Type type, MemberInfo memberInfo, bool inherit = tru
 								IsPrimaryKey    = isPrimaryKey,
 								PrimaryKeyOrder = primaryKeyOrder,
 								IsIdentity      = isIdentity,
-								IsDiscriminator = discriminator == prop
+								IsDiscriminator = discriminator == prop,
+								SkipOnInsert    = skipOnInsert,
+								SkipOnUpdate    = skipOnUpdate
 							}
 						};
 					}

Tests/LinqToDB.EntityFrameworkCore.PostgreSQL.Tests/Models/NpgSqlEntities/NpgSqlEnititesContext.cs

@@ -24,10 +24,17 @@ protected override void OnModelCreating(ModelBuilder modelBuilder)
 			modelBuilder.Entity<EntityWithArrays>(entity =>
 			{
 			});
+
+			modelBuilder.Entity<EntityWithXmin>(entity =>
+			{
+				entity.UseXminAsConcurrencyToken();
+			});
+
 		}
 
 		public virtual DbSet<Event> Events { get; set; } = null!;
 		public virtual DbSet<EntityWithArrays> EntityWithArrays { get; set; } = null!;
+		public virtual DbSet<EntityWithXmin> EntityWithXmin { get; set; } = null!;
 
 	}
 }

Tests/LinqToDB.EntityFrameworkCore.PostgreSQL.Tests/NpgSqlTests.cs

@@ -87,6 +87,19 @@ where Sql.Ext.PostgreSQL().Overlaps(m.Guids, guids)
 			}
 		}
 
+		[Test]
+		public void TestConcurrencyToken()
+		{
+			using var db = CreateNpgSqlEntitiesContext();
+
+			var toInsert = Enumerable.Range(1, 10)
+				.Select(i => new EntityWithXmin { Value = "Str" + i })
+				.ToArray();
+
+			db.BulkCopy(toInsert);
+		}
+
+
 		[Test]
 		public void TestUnnest()
 		{