标签：new int tran 插入 ati 有一个 tor 一个 是你
假设你有一个表Authors ,主键是AuthorId
Author author = new Author() { AuthorId = 1001, Name = "Johny", Books = new List<Book> { new Book() { Title = "Learn VB.NET"}, new Book() { Title = "C# Fundamentals for Absolute Beginners"}, } };
你想保存这个图,但是你指定了主键的值是1001,这里你不能直接savechanges,你应该首先打开IDENTITY_INSERT,保存后再删除
using (var context = new BookStore()) { Author author = new Author() { AuthorId = 1001, Name = "Johny", Books = new List<Book> { new Book() { Title = "Learn VB.NET"}, new Book() { Title = "C# Fundamentals for Absolute Beginners"}, } }; context.Authors.Add(author); context.Database.ExecuteSqlCommand(@"SET IDENTITY_INSERT [dbo].[Authors] ON"); context.SaveChanges(); context.Database.ExecuteSqlCommand(@"SET IDENTITY_INSERT [dbo].[Authors] OFF"); }
但是这时保存的数据的 id不是1001,而会是数据库identity生成的序号
解决的方法是派生一个 datacontext的子类重写OnModelCreating
public class TempBookStore : BookStore { protected override void OnModelCreating(DbModelBuilder modelBuilder) { modelBuilder.Entity<Author>() .Property(a => a.AuthorId) .HasDatabaseGeneratedOption(DatabaseGeneratedOption.None); base.OnModelCreating(modelBuilder); } }
然后在事务中savechangs
using (var context = new TempBookStore()) { using (var transaction = context.Database.BeginTransaction()) { Author author = new Author() { AuthorId = 1001, Name = "Johny", Books = new List<Book> { new Book() { Title = "Learn VB.NET"}, new Book() { Title = "C# Fundamentals for Absolute Beginners"}, } }; context.Authors.Add(author); context.Database.ExecuteSqlCommand(@"SET IDENTITY_INSERT [dbo].[Authors] ON"); context.SaveChanges(); context.Database.ExecuteSqlCommand(@"SET IDENTITY_INSERT [dbo].[Authors] OFF"); transaction.Commit(); } }
标签：new int tran 插入 ati 有一个 tor 一个 是你
原文地址：https://www.cnblogs.com/nocanstillbb/p/11494987.html
