c# - 为什么调用 modelBuilder.Entity() 会添加配置？

Question

我想即时将域类型添加到上下文中。重写 OnModelCreating ，添加类型和配置添加的类型是我假设的非常自然的方式:

public MyContext : DbContext
{
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);
        modelBuilder.Entity<MyEntity>();
        modelBuilder.Configurations.Add(new MyEntityConfig())(); // throws exception            
    }
}

class MyEntityConfig : EntityTypeConfiguration<MyEntity>
{
}

但令人惊讶的是，modelBuilder.Configurations.Add(new MyEntityConfig())()抛出以下异常:

An exception of type 'System.InvalidOperationException' occurred in EntityFramework.dll but was not handled in user code.

Additional information: A configuration for type 'MyEntity' has already been added. To reference the existing configuration use the Entity() or ComplexType() methods.

检查 modelbuilder.Configurations透露调用.Set<T>导致自动添加配置。

有什么解决办法吗？

Answer 1

感谢 sstan 和 DavidL，命令的正确执行顺序是:

base.OnModelCreating(modelBuilder);
modelBuilder.Configurations.Add(new MyEntityConfig())(); 
modelBuilder.Entity<MyEntity>();