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  • Entity Framework搜索指定字段解决方案

    public class Book
    {
            [Key]
            [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
            public int Id { get; set; }
    
            [Required, MaxLength(50)]
            public string Title { get; set; }
            public Double? Price { get; set; }
    }

    解决方案一:

    var bkList = db.Books.Select(allBooks => new { Id = allBooks.Id, Title = allBooks.Title }).Select(b => new Book { Id=b.Id,Title=b.Title});

    解决方案二:

    var bkList2 = db.Books.Select(allBooks => new { Id = allBooks.Id, Title = allBooks.Title }).ToList().ConvertAll<Book>(b => new Book(){ Id=b.Id,Title=b.Title});

    解决方案三:

    //声明一个与Book一模一样的克隆类
    public class BookClone
    {
        public int Id { get; set; }
    
        public string Title { get; set; }
    
        public Double Price { get; set; }
    }
    
    var bkList3 = db.Books.Select(allBooks => new BookClone { Id = allBooks.Id, Title = allBooks.Title });

    这三种方案都可以解决The entity or complex type '{0}' cannot be constructed in a LINQ to Entities query. 的异常

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  • 原文地址:https://www.cnblogs.com/pcmax/p/Entity_Framework.html
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