MVC - 实体框架 - 元数据关系

发布于 2024-12-22 10:19:53 字数 1142 浏览 7 评论 0原文

今天我第一次使用 MVC。通常我首先使用带有模型的 EF，但我想尝试 POCO。

所以我已经创建了 3 个实体，当我尝试创建控制器时出现错误：

无法检索“BookExchange.Models.Exchange”的元数据。无法确定类型“BookExchange.Models.Exchange”和“BookExchange.Models.Book”之间关联的主体端。此关联的主体必须使用关系流畅 API 或数据注释显式配置。

我的三堂课：

public class Book
{
    public int BookID { get; set; }
    public string Name { get; set; }
    public string Author { get; set; }
    public string ISBN10 { get; set; }

    public int PersonID { get; set; }
    public virtual Person Person { get; set; }

    public virtual Exchange Exchange { get; set; }
}

public class Person
{
    public int PersonID { get; set; }
    public string Name { get; set; }
    public virtual ICollection<Book> Books { get; set; }
    public virtual ICollection<Exchange> Exchanges { get; set; }
}

public class Exchange
{
    [Key]
    public int BookID { get; set; }

    public int PersonID { get; set; }
    public DateTime ReturnDate { get; set; }

    public virtual Person Person { get; set; }
    public virtual Book Book { get; set; }
}

有谁知道我做错了什么？我不想失去关联属性。

提前致谢！

原文

Today I've been working with MVC for the first time. Also normally I use the EF with model first, but I wanted to try POCO.

So I've made my 3 entities and when I try to make a controller I get an error:

Unable to retrieve metadata for "BookExchange.Models.Exchange". Unable to determine the principal end of an association between the types "BookExchange.Models.Exchange" and "BookExchange.Models.Book". The principal end of this association must be explicitly configured using either the relationship fluent API or data annotations.

My 3 classes:

public class Book
{
    public int BookID { get; set; }
    public string Name { get; set; }
    public string Author { get; set; }
    public string ISBN10 { get; set; }

    public int PersonID { get; set; }
    public virtual Person Person { get; set; }

    public virtual Exchange Exchange { get; set; }
}

public class Person
{
    public int PersonID { get; set; }
    public string Name { get; set; }
    public virtual ICollection<Book> Books { get; set; }
    public virtual ICollection<Exchange> Exchanges { get; set; }
}

public class Exchange
{
    [Key]
    public int BookID { get; set; }

    public int PersonID { get; set; }
    public DateTime ReturnDate { get; set; }

    public virtual Person Person { get; set; }
    public virtual Book Book { get; set; }
}

Does anyone know what I'm doing wrong? I don't want to lose the association properties.

Thanks in advance!

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云归处 2024-12-29 10:19:53

尝试添加外键属性以供参考。例如

public class Book
{
    public int BookID { get; set; }
    public string Name { get; set; }
    public string Author { get; set; }
    public string ISBN10 { get; set; }

    public virtual Person Person { get; set; }
    public int PersonID { get; set; }
    public virtual Exchange Exchange { get; set; }
    public int ExchangeID { get; set; }
}

public class Person
{
    public int PersonID { get; set; }
    public string Name { get; set; }
    public virtual ICollection<Book> Books { get; set; }
    public virtual ICollection<Exchange> Exchanges { get; set; } 
}

public class Exchange
{
    public int ExchangeID { get; set; }

    public int BookID { get; set; }
    public virtual Book Book { get; set; }
    public int PersonID { get; set; }
    public virtual Person Person { get; set; }

    public DateTime ReturnDate { get; set; }
}

，另外，看看 ScottGu 关于代码优先的帖子和这篇关于约定的 EF 帖子。

Try adding foreign key properties for your references. E.g.

public class Book
{
    public int BookID { get; set; }
    public string Name { get; set; }
    public string Author { get; set; }
    public string ISBN10 { get; set; }

    public virtual Person Person { get; set; }
    public int PersonID { get; set; }
    public virtual Exchange Exchange { get; set; }
    public int ExchangeID { get; set; }
}

public class Person
{
    public int PersonID { get; set; }
    public string Name { get; set; }
    public virtual ICollection<Book> Books { get; set; }
    public virtual ICollection<Exchange> Exchanges { get; set; } 
}

public class Exchange
{
    public int ExchangeID { get; set; }

    public int BookID { get; set; }
    public virtual Book Book { get; set; }
    public int PersonID { get; set; }
    public virtual Person Person { get; set; }

    public DateTime ReturnDate { get; set; }
}

Also, take a look at ScottGu's post on code first and this EF post on conventions.

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℡Ms空城旧梦 2024-12-29 10:19:53

试试这个：（删除数据库，这样 EF 将创建新的）

public class Book
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Author { get; set; }
    public string ISBN { get; set; }

    public virtual Person Person { get; set; }
    public virtual Exchange Exchange { get; set; }
}

public class Person
{
    public int Id { get; set; }
    public string Name { get; set; }

    public virtual ICollection<Book> Books { get; set; }
    public virtual ICollection<Exchange> Exchanges { get; set; }
}

public class Exchange
{    
    public int Id { get; set; }   
    public DateTime ReturnDate { get; set; }

    public virtual Person Person { get; set; }
    public virtual Book Book { get; set; }
}

Try this: (Remove database, so EF will create new)

public class Book
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Author { get; set; }
    public string ISBN { get; set; }

    public virtual Person Person { get; set; }
    public virtual Exchange Exchange { get; set; }
}

public class Person
{
    public int Id { get; set; }
    public string Name { get; set; }

    public virtual ICollection<Book> Books { get; set; }
    public virtual ICollection<Exchange> Exchanges { get; set; }
}

public class Exchange
{    
    public int Id { get; set; }   
    public DateTime ReturnDate { get; set; }

    public virtual Person Person { get; set; }
    public virtual Book Book { get; set; }
}

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