FluentNHibernate: Automapping OneToMany relation using attribute and convention

问题

This is very similar to my previous question: FluentNHibernate: How to translate HasMany(x => x.Addresses).KeyColumn("PersonId") into automapping

Say I have these models:

public class Person
{
    public virtual int Id { get; private set; }
    public virtual ICollection<Address> Addresses { get; private set; }
}

public class Address
{
    public virtual int Id { get; private set; }
    public virtual Person Owner { get; set; }
}

I want FluentNHibernate to create the following tables:

Person
    PersonId
Address
    AddressId
    OwnerId

This can be easily achieved by using fluent mapping:

public class PersonMapping : ClassMap<Person>
{
    public PersonMapping()
    {
        Id(x => x.Id).Column("PersonId");
        HasMany(x => x.Addresses).KeyColumn("OwnerId");
    }
}

public class AddressMapping : ClassMap<Address>
{
    public AddressMapping()
    {
        Id(x => x.Id).Column("AddressId");
        References(x => x.Person).Column("OwnerId");
    }
}

I want to get the same result by using auto mapping. I tried the following conventions:

class PrimaryKeyNameConvention : IIdConvention
{
    public void Apply(IIdentityInstance instance)
    {
        instance.Column(instance.EntityType.Name + "Id");
    }
}

class ReferenceNameConvention : IReferenceConvention
{
    public void Apply(IManyToOneInstance instance)
    {
        instance.Column(string.Format("{0}Id", instance.Name));
    }
}

// Copied from @Fourth: https://stackoverflow.com/questions/6091290/fluentnhibernate-how-to-translate-hasmanyx-x-addresses-keycolumnpersonid/6091307#6091307
public class SimpleForeignKeyConvention : ForeignKeyConvention
{
    protected override string GetKeyName(Member property, Type type)
    {
        if(property == null)
            return type.Name + "Id";
        return property.Name + "Id";
    }
}

But it created the following tables:

Person
    PersonId
Address
    AddressId
    OwnerId
    PersonId // this column should not exist

So I added a AutoMappingOverride:

public class PersonMappingOverride : IAutoMappingOverride<Person>
{
    public void Override(AutoMapping<Person> mapping)
    {
        mapping.HasMany(x => x.Addresses).KeyColumn("OwnerId");
    }
}

This correctly solved the problem. But I want to get the same result using attribute & convention. I tried:

public class Person
{
    public virtual int Id { get; private set; }

    [KeyColumn("OwnerId")]
    public virtual ICollection<Address> Addresses { get; private set; }
}

class KeyColumnAttribute : Attribute
{
    public readonly string Name;

    public KeyColumnAttribute(string name)
    {
        Name = name;
    }
}

class KeyColumnConvention: IHasManyConvention
{
    public void Apply(IOneToManyCollectionInstance instance)
    {
        var keyColumnAttribute = (KeyColumnAttribute)Attribute.GetCustomAttribute(instance.Member, typeof(KeyColumnAttribute));
        if (keyColumnAttribute != null)
        {
            instance.Key.Column(keyColumnAttribute.Name);
        }
    }
}

But it created these tables:

Person
    PersonId
Address
    AddressId
    OwnerId
    PersonId // this column should not exist

Below is the rest of my code:

ISessionFactory sessionFactory = Fluently.Configure()
    .Database(MsSqlConfiguration.MsSql2008.ConnectionString(connectionString))
    .Mappings(m =>
                m.AutoMappings.Add(AutoMap.Assemblies(typeof(Person).Assembly)
                    .Conventions.Add(typeof(PrimaryKeyNameConvention))
                          .Conventions.Add(typeof(PrimaryKeyNameConvention))
                          .Conventions.Add(typeof(ReferenceNameConvention))
                          .Conventions.Add(typeof(SimpleForeignKeyConvention))
                          .Conventions.Add(typeof(KeyColumnConvention)))

                //m.FluentMappings
                //    .Add(typeof (PersonMapping))
                //    .Add(typeof (AddressMapping))
    )
    .ExposeConfiguration(BuildSchema)
    .BuildConfiguration()
    .BuildSessionFactory();

Any ideas? Thanks.

Update:

The test project can be downloaded from here.

回答1:

Sigh... Learning NHibernate is really a hair pulling experience.

Anyway I think I finally figured out how to solve this problem: Just remove the SimpleForeignKeyConvention and everything will work fine.

It seems the SimpleForeignKeyConvention conflicts with both ReferenceKeyConvention & KeyColumnConvention. It has higher priority than KeyColumnConvention but lower priority than ReferenceKeyConvention.

public class SimpleForeignKeyConvention : ForeignKeyConvention
{
    protected override string GetKeyName(Member property, Type type)
    {
        if(property == null)
            // This line will disable `KeyColumnConvention`
            return type.Name + "Id";

        // This line has no effect when `ReferenceKeyConvention` is enabled.
        return property.Name + "Id";
    }
}

回答2:

I've tested your classes with FHN's auto-mapping feature and it does not create that second PersonId on Address table. I'm using FHN v1.2.0.721 from here

来源：https://stackoverflow.com/questions/6091654/fluentnhibernate-automapping-onetomany-relation-using-attribute-and-convention

标签

nhibernate

fluent-nhibernate

automapping