在 Fluent NHibernate 中将 IUserType 映射到组件属性

Question

我正在尝试为州和国家/地区代码实现一个 IUserType ，这将允许我访问两个字母的代码（存储在数据库中的内容）以及全名。我正在遵循 NHibernate 3.0 Cookbook (p. 225) 中的示例，但我的问题是我的 StreetAddress 类当前在我的自动映射配置中映射为组件：

public override bool IsComponent(Type type)
{
    return type == typeof(StreetAddress);
}

将此类标识为组件，我不知道如何使用 IUserType 作为组件类的属性，因为该类没有显式映射。我无法告诉流畅的 NHibernate 使用 IUserType 规范。

Answer 1

@Firo 很接近，但事实证明有一个更简单的解决方案。这里有两个步骤。首先，我必须告诉 Fluent NHibernate 不要映射位于我的域层中的 State 和 Country 类：

public override bool ShouldMap(Type type)
{
    return type.Name != "State" && type.Name != "Country";
}

接下来，我只需为 State 和 Country 类创建约定 ：代码>IUserType类。事实证明，这比 @Firo 建议的更容易：

public class CountryUserTypeConvention : UserTypeConvention<CountryType>
{
}

public class StateUserTypeConvention : UserTypeConvention<StateType>
{
}

这些 IUserTypes 的定义是从原始问题中引用的食谱中取出的，但如果您不想阅读它：

public class CountryType : GenericWellKnownInstanceType<Country, string>
{
    // The StateType is pretty much the same thing, only it uses "StateCode" instead of "CountryCode"
    private static readonly SqlType[] sqlTypes =
        new[] {SqlTypeFactory.GetString(2)};

    public CountryType()
        : base(new Countries(),
               (entity, id) => entity.CountryCode == id,
               entity => entity.CountryCode)
    {
    }

    public override SqlType[] SqlTypes
    {
        get { return sqlTypes; }
    }
}

那就得出来自GenericWellKnownInstanceType：

[Serializable]
public abstract class GenericWellKnownInstanceType<T, TId> :
    IUserType where T : class
{
    private Func<T, TId, bool> findPredicate;
    private Func<T, TId> idGetter;
    private IEnumerable<T> repository;

    protected GenericWellKnownInstanceType(
        IEnumerable<T> repository,
        Func<T, TId, bool> findPredicate,
        Func<T, TId> idGetter)
    {
        this.repository = repository;
        this.findPredicate = findPredicate;
        this.idGetter = idGetter;
    }

    public Type ReturnedType
    {
        get { return typeof (T); }
    }

    public bool IsMutable
    {
        get { return false; }
    }

    public new bool Equals(object x, object y)
    {
        if (ReferenceEquals(x, y))
        {
            return true;
        }
        if (ReferenceEquals(null, x) ||
            ReferenceEquals(null, y))
        {
            return false;
        }
        return x.Equals(y);
    }

    public int GetHashCode(object x)
    {
        return (x == null) ? 0 : x.GetHashCode();
    }

    public object NullSafeGet(IDataReader rs,
                              string[] names, object owner)
    {
        int index0 = rs.GetOrdinal(names[0]);
        if (rs.IsDBNull(index0))
        {
            return null;
        }
        var value = (TId) rs.GetValue(index0);
        return repository.FirstOrDefault(x =>
                                         findPredicate(x, value));
    }

    public void NullSafeSet(IDbCommand cmd,
                            object value, int index)
    {
        if (value == null)
        {
            ((IDbDataParameter) cmd.Parameters[index])
                .Value = DBNull.Value;
        }
        else
        {
            ((IDbDataParameter) cmd.Parameters[index])
                .Value = idGetter((T) value);
        }
    }

    public object DeepCopy(object value)
    {
        return value;
    }

    public object Replace(object original,
                          object target, object owner)
    {
        return original;
    }

    public object Assemble(object cached, object owner)
    {
        return cached;
    }

    public object Disassemble(object value)
    {
        return value;
    }

    /// <summary>
    /// The SQL types for the columns
    /// mapped by this type.
    /// </summary>
    public abstract SqlType[] SqlTypes { get; }
}

这些类的存储库只是State 和Country 对象的一对ReadOnlyCollection。再次，来自食谱：

public class States : ReadOnlyCollection<State>
{
    // Truncated in the interest of brevity
    public static State Arizona = new State("AZ", "Arizona");
    public static State Florida = new State("FL", "Florida");
    public static State California = new State("CA", "California");
    public static State Colorado = new State("CO", "Colorado");
    public static State Oklahoma = new State("OK", "Oklahoma");
    public static State NewMexico = new State("NM", "New Mexico");
    public static State Nevada = new State("NV", "Nevada");
    public static State Texas = new State("TX", "Texas");
    public static State Utah = new State("UT", "Utah");

    public States() : base(new State[]
                               {
                                   Arizona, Florida, California, Colorado,
                                   Oklahoma, NewMexico, Nevada, Texas, Utah
                               }
        )
    {
    }
}

希望这对那里的人有帮助。

Answer 2

我无法测试它，但使用约定应该是可能的

public class ComponentConvention : IComponentConvention, IComponentConventionAcceptance
{
    public void Accept(IAcceptanceCriteria<IComponentInspector> criteria)
    {
        criteria.Expect(x => x.Type == typeof(StreetAddress);
    }

    public void Apply(IComponentInstance instance)
    {
        instance.Properties.First(p => p.Name == "CountrCode").CustomType<MyUserType>();
    }
}