实体框架代码首先允许在单独的文件中流畅的映射？ [英] Does Entity Framework Code First allow for fluent mappings in separate files?

问题描述

我正在使用Entity Framework Code First开发一个相当大的数据库模式。我喜欢通过数据注释方法的Fluent API，因为它将我的域对象作为简单的POCO。

为了使用Fluent API，我必须覆盖OnModelCreating从DbContext继承的类。

我不喜欢所有的实体的所有映射都在这种方法中。我以前使用过FluentNHibernate，每个实体都有它自己的映射类。 EF有什么类似的吗？

我想我可以创建自己的接口来实现映射类，并在OnModelCreating方法中调用它们。我可以使用反射或IoC来发现它们。我没有特别看到这种方法有什么问题，但是我想知道实体框架是否已经附带这样的东西？

解决方案

您可以从 EntityTypeConfiguration< TEntity> 派生的实体创建一个配置类，并将这些类放入单独的文件中。在派生的 DbContext 中，将这些配置类的实例添加到模型构建器。示例：

  public class UserConfiguration：EntityTypeConfiguration< User> 
 {
 public UserConfiguration（）
 {
 HasKey（u => u.UserName）; 
 
属性（u => u.UserName）
 .HasMaxLength（50）
 .IsRequired（）; 
 
 //等
} 
} 
 
 public class RoleConfiguration：EntityTypeConfiguration< Role> 
 {
 public RoleConfiguration（）
 {
 HasKey（r => r.RoleName）; 
 
 //等
} 
} 
  

派生上下文：

  public class MyContext：DbContext 
 {
 // ... 
 
 protected override void OnModelCreating（DbModelBuilder modelBuilder）
 {
 modelBuilder.Configurations.Add（new UserConfiguration（））; 
 modelBuilder.Configurations.Add（new RoleConfiguration（））; 
} 
} 
  

还有一个 ComplexTypeConfiguration< ; T> 您可以从中配置复杂类型。

I am developing a rather large database schema using Entity Framework Code First. I prefer the Fluent API over the Data Annotations approach, as it leaves my domain objects as simple POCOs.

In order to use Fluent API, I have to override OnModelCreating in the class that inherits from DbContext.

I don't like that all mappings for all of my entities are in this one method. I have used things like FluentNHibernate before, where each entity has it's own mapping class. Does EF have anything similar?

I suppose I could create my own interface to implement a mapping class and call them all within the OnModelCreating method. I could use reflection or an IoC to discover them all. I don't particularly see anything wrong with this approach, but I was wondering if Entity Framework already comes with something like this out of the box?

解决方案

You can create one configuration class per entity derived from EntityTypeConfiguration<TEntity> and put these classes into separate files. In your derived DbContext you add instances of those configuration classes to the model builder. Example:

public class UserConfiguration : EntityTypeConfiguration<User>
{
    public UserConfiguration()
    {
        HasKey(u => u.UserName);

        Property(u => u.UserName)
            .HasMaxLength(50)
            .IsRequired();

        // etc.
    }
}

public class RoleConfiguration : EntityTypeConfiguration<Role>
{
    public RoleConfiguration()
    {
        HasKey(r => r.RoleName);

        // etc.
    }
}

Derived context:

public class MyContext : DbContext
{
    //...

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Configurations.Add(new UserConfiguration());
        modelBuilder.Configurations.Add(new RoleConfiguration());
    }
}

There is also a ComplexTypeConfiguration<T> you can derive from to configure complex types.

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