如何用“一对多”关系序列化两个对象?

我有两个班: Lookup 和 LookupItem 那个 查找 名为的成员 Items 这是一个集合 查找项 我无法序列化 查找 或 查找项 . 第一次出错 The type LookupItem was not expected. Use the XmlInclude or SoapInclude attribute to specify types that are not known statically. 第二次我出错了 A circular reference was detected while serializing an object of type Lookup. .

我怎样才能解决这个问题?

我使用以下代码进行序列化:

public static string Serialize(object obj)
{
    XmlSerializer ser = new XmlSerializer(obj.GetType());
    StringBuilder sb = new StringBuilder();
    StringWriter writer = new StringWriter(sb);
    ser.Serialize(writer, obj);
    return sb.ToString();
}

更新: 课程框架:

[活动记录(lazy=true)] 公共类查找:ActiveRecordExtender,IComparable { 公共查找() { }

[Property]
public virtual string Title { set; get; } 

// creating relation
[HasMany(typeof(LookupItem), Cascade = ManyRelationCascadeEnum.All)]
public virtual IList Items { set; get; }

}

[活动记录(lazy=true)] 公共类LookupItem:ActiveRecordExtender { 公共查找项() { }

//creating relation
[BelongsTo("Lookup_ID")]
public virtual Lookup ContainerLookup { set; get; }

[Property]
public virtual string Title { set; get; } 

[Property]
public virtual string Value { set; get; } 

[Property]
public virtual int SortOrder { set; get; }

}

请注意,我正在使用Catle ActiveRecord作为ORM,请注意,此问题与继承无关。 ActiveRecordBase . 因为这个域中没有关系的其他类工作正常。