实体框架，POCO和私有财产

Question

I've created the following POCO class and also made Contact.FirstName and Contact.LastName properties private ( these properties are mapped to appropriate properties in an Entity Framework model ).

public class Contact
{
    public int ContactID { get; set; }
    private string FirstName { get; set; }
    public string LastName { get; private set; }
}

I expected to get an exception due to EF not being able to assign values to these two properties, but somehow EF still managed to assign values to them. How is that possible, since only code in Contact class should have accesses to private properties?

Thank you

Answer 1

在具有足够信任级别的环境中，可以使用反射来访问通常无法访问的成员。

Answer 2

For completeness' sake: EF5 code first doesn't (at least by default) map private properties to a database table column.

The following class:

public class Person {
  public int PersonId { get; set; }
  private string Name { get; set; }
}

With the following DbContext:

public class PrivatePropertiesContext : DbContext {
  public DbSet<Person> People {
    get;
    set;
  }
}

Generates a People table with only one column: dbo.People.PersonId (PK, int, not null)

A public key property is required by default code first conventions. If the PersonId property in the Person class would be private or protected, entity framework throws the following exception:

System.Data.Entity.Edm.EdmEntityType: : EntityType 'Person' has no key defined. Define the key for this EntityType.
System.Data.Entity.Edm.EdmEntitySet: EntityType: EntitySet 'People' is based on type 'Person' that has no keys defined.

Answer 3

Yes - EF, code first are utilizing that in couple places.

I've seen similar behavior with private constructors - EF/CF can still construct your objects even if you 'hide' it, or try to :) (that was the behavior in earlier versions, not sure now).

And I remember having some discussion with CF people on why they don't initialize complex-type properties - vs they still are ok with accessing private members (if I recall correctly), was a long ago.

So, a bit of general question - but in that sense hope this clarifies something at least.