System.InvalidOperationException: The type MyContext+Northwind was not mapped. Check that the type has not been explicitly excluded by using the Ignore method or NotMappedAttribute data annotation. Verify that the type was defined as a class, is not primitive, nested or generic, and does not inherit from EntityObject.
错误原因:
entity framework不能将内部类与数据库匹配。
错误代码如下所示:
1 using System; 2 using System.Collections.Generic; 3 using System.Linq; 4 using System.Text; 5 using System.Data.Entity; 6 using System.ComponentModel.DataAnnotations; 7 8 namespace TestCodeFirst 9 { 10 public class MyContext 11 { 12 public class Product 13 { 14 public int ProductID { get; set; } 15 public int CategoryID { get; set; } 16 [Required(ErrorMessage = "Product Name不能为空")] 17 public string ProductName { get; set; } 18 public Decimal? UnitPrice { get; set; } 19 public bool Discontinued { get; set; } 20 public virtual Category Category { get; set; } 21 } 22 23 public class Category 24 { 25 public int CategoryID { get; set; } 26 public string CategoryName { get; set; } 27 public string Description { get; set; } 28 public byte[] Picture { get; set; } 29 public virtual ICollection<Product> Product { get; set; } 30 } 31 public class Northwind : DbContext 32 { 33 public DbSet<Product> Products { get; set; } 34 public DbSet<Category> Categorys { get; set; } 35 } 36 } 37 }
解决的办法:Northwind作为内部类。正确的代码如下所示
1 namespace TestCodeFirst 2 { 3 public class Product 4 { 5 public int ProductID { get; set; } 6 public int CategoryID { get; set; } 7 [Required(ErrorMessage="Product Name不能为空")] 8 public string ProductName { get; set; } 9 public Decimal? UnitPrice { get; set; } 10 public bool Discontinued { get; set; } 11 public virtual Category Category { get; set; } 12 } 13 14 public class Category 15 { 16 public int CategoryID { get; set; } 17 public string CategoryName { get; set; } 18 public string Description { get; set; } 19 public byte[] Picture { get; set; } 20 public virtual ICollection<Product> Product { get; set; } 21 } 22 public class Northwind:DbContext 23 { 24 public DbSet<Product> Products { get; set; } 25 public DbSet<Category> Categorys { get; set; } 26 } 27 }