FluentNHibernate 异常：复合用户类型上的“属性映射的列数错误”答案

【问题标题】：FluentNHibernate Exception: "Property mapping has wrong number of columns" on composite user typeFluentNHibernate 异常：复合用户类型上的“属性映射的列数错误”
【发布时间】：2018-07-25 09:27:07
【问题描述】：

我正在尝试将我的域模型中的一组实体映射到我的数据库中以逗号分隔的 id 字符串。我已经编写了一个复合用户类型来为我处理这个问题：

       public class CustomerSetToCommaString : ICompositeUserType
{
    public object GetPropertyValue(object component, int property)
    {
        throw new NotImplementedException();
    }

    public void SetPropertyValue(object component, int property, object value)
    {
        throw new NotImplementedException();
    }

    public bool Equals(object x, object y)
    {
        var set1 = x as ISet<Customer>;
        var set2 = x as ISet<Customer>;

        return (x == null) ? y == null : set1.SetEquals(set2);
    }

    public int GetHashCode(object x)
    {
        var set = x as ISet<Customer>;
        unchecked
        {
            return set == null ? 0 : set.Sum(relatie => relatie.GetHashCode());
        }
    }

    public object NullSafeGet(DbDataReader dr, string[] names, ISessionImplementor session, object owner)
    {
        var str = (string)NHibernateUtil.String.Get(dr, names[0], session);
        IList<int> ids = str.Split(',').Select(id => int.Parse(id.Trim())).ToList();
        return ((ISession) session).QueryOver<Customer>().WhereRestrictionOn(customer => customer.Id).IsInG(ids).List()
            .ToHashSet();
    }

    public void NullSafeSet(DbCommand cmd, object value, int index, bool[] settable, ISessionImplementor session)
    {
        var set = value as ISet<Customer>;
        NHibernateUtil.String.Set(cmd, string.Join(", ", set.Select(customer => customer.Id.ToString()).ToArray()), index, session);
    }

    public object DeepCopy(object value)
    {
        return ((ISet<Customer>) value).ToHashSet();
    }

    public object Disassemble(object value, ISessionImplementor session)
    {
        return DeepCopy(value);
    }

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

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

    public string[] PropertyNames => new string[0];
    public IType[] PropertyTypes  => new IType[0];
    public Type ReturnedClass => typeof(ISet<Customer>);
    public bool IsMutable => true;
}

但是，当尝试使用 Map(x => x.Customers).CustomType<CustomerSetToCommaString>.Column("Customers"); 我得到属性映射的列数错误的异常。它不应该尝试映射到单个列吗？我错过了什么吗？

【问题讨论】：

标签： c# nhibernate orm fluent-nhibernate

【解决方案1】：

经过一天令人沮丧的调试和谷歌搜索后，我找到了答案。问题出在这一行：

public IType[] PropertyTypes  => new IType[0];

这指定需要填充的列。当我将其更改为：

public IType[] PropertyTypes  => new IType[1]{NHibernateUtil.String};

我指定该列是单个字符串，这解决了问题。

【讨论】：