种子数据是重复代码第一次迁移

问题描述：

我已经使用代码第一次迁移种子数据库，但是我注意到当我在index.html中查看种子数据时，数据被复制。种子数据是重复代码第一次迁移

这是在配置文件是我接种数据：

内部密封类配置：DbMigrationsConfiguration { 公共配置（） { AutomaticMigrationsEnabled = FALSE; }

protected override void Seed(OnlineBookStore.Models.OnlineBookStoreDB context) 
    { 

     var books = new System.Collections.Generic.List<Book> 
     { 
      new Book { 

     BookStatus = new BookStatus { Status = "New" }, 
      Genre = new Genre { Name = "Thriller" }, 
      Author = new Author { Name = "Paula Hawkins" }, 
      Title = "The Girl On The Train", 
      Description = "Rachel catches the same commuter train   morning. ", 
      ISBN = 0552779776, 

      }, 


     new Book 
     { 
      BookStatus = new BookStatus { Status = "Best Seller" }, 
      Genre = new Genre { Name = "Childrens" }, 
      Author = new Author { Name = "Roald Dahl" }, 
      Title = "The Witches", 
      Description = "Beware. Real witches dress in ordinary clothes", 


      ISBN = 0141365471, 

     }, 
     }, 

     }; 

books.ForEach(s =>context.Books.AddOrUpdate(p => new { p.ISBN, p.Title })); 
      context.SaveChanges(); 


    } 
}

}

我真的不能确定是我错的，花费数天时间在此！真的很感谢任何人的帮助！谢谢！

答

您需要在AddOrUpdate中指定密钥以防止重复，因为Seed（）在每个发布的更新数据库都运行。

// build your books collection 
    var books = new [] 
    { 
     new Book { 

    BookStatus = new BookStatus { Status = "New" }, 
     Genre = new Genre { Name = "Thriller" }, 
     Author = new Author { Name = "Paula Hawkins" }, 
     Title = "The Girl On The Train", 
     Description = "Rachel catches the same commuter train   morning. ", 
     ISBN = 0552779776, 

     }, 


    new Book 
    { 
     BookStatus = new BookStatus { Status = "Best Seller" }, 
     Genre = new Genre { Name = "Childrens" }, 
     Author = new Author { Name = "Roald Dahl" }, 
     Title = "The Witches", 
     Description = "Beware. Real witches dress in ordinary clothes", 


     ISBN = 0141365471, 

    }, 
    }, 

    };  


context.Books.AddOrUpdate(p => new { p.ISBN, p.Title }, books); 
context.SaveChanges();

见http://thedatafarm.com/data-access/take-care-with-ef-4-3-addorupdate-method/

感谢，我这样做，但它指出p没有在当前的背景下存在的，在下面的代码中，p是被我认为错误是因为它是（在P）突出显示红色：新{p.ISBN，p.Title} –

对不起，无意识地复制了代码。如果你已经建立了一个集合，你不需要foreach。请参阅编辑。 –

谢谢，试过你的代码，它不起作用，下面的代码中的书出现为错误，context.Books.AddOrUpdate（p => new {p.ISBN，p.Title}，books）; –

种子数据是重复代码第一次迁移

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