種子數據是重複代碼第一次遷移

我已經使用代碼第一次遷移種子數據庫，但是我注意到當我在index.html中查看種子數據時，數據被複制。種子數據是重複代碼第一次遷移

這是在配置文件是我接種數據：

內部密封類配置：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(); 


    } 
}

}

我真的不能確定是我錯的，花費數天時間在此！真的很感謝任何人的幫助！謝謝！

來源

2016-11-14 Swati Sinha

您需要在AddOrUpdate中指定密鑰以防止重複，因爲Seed（）在每個發佈的更新數據庫都運行。

// 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();

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

來源

2016-11-14 17:38:31

感謝，我這樣做，但它指出p沒有在當前的背景下存在的，在下面的代碼中，p是被我認爲錯誤是因爲它是（在P）突出顯示紅色：新{p.ISBN，p.Title} –

對不起，無意識地複製了代碼。如果你已經建立了一個集合，你不需要foreach。請參閱編輯。 –

謝謝，試過你的代碼，它不起作用，下面的代碼中的書出現爲錯誤，context.Books.AddOrUpdate（p => new {p.ISBN，p.Title}，books）; –

種子數據是重複代碼第一次遷移

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