nhibernate:字符串的读写列表 [英] nhibernate : read write list of string

问题描述

我知道我可以使用nhibernate读取下面的字符串写列表

I know I can read write list of string like below using nhibernate

HasMany(x => x.Attachments)
    .KeyColumn("RowId")
    .Table("PostTable").Element("PostKey");

但这会创建一个额外的表，例如 UserType 或其他名称，以便我们可以直接写入列表...如果是的话，使用nhibernate自定义UserType的任何示例吗?带有示例代码...

But this creates an extra table, is there a way e.g. UserType or something else, so that we can directly write to list... if yes any example of custom UserType using nhibernate?? with sample code...

我还希望如果我向列表中添加值，也应该保存.我在下面看到了示例代码，如果我们将值添加到列表中，该代码会中断...

I also want that If i add value to list that also should be saved. I have seen below example code which breaks in case we add value to list...

   private virtual string StringValue
   public virtual IList<string> valueList
        { 
          get { return StringValue; }
          set { StringValue = string.Join(value, "|"); } 
         }

推荐答案

您可以使用IUserType来做到这一点，

You can do this with IUserType like so:

public class DelimitedList : IUserType
{
    private const string delimiter = "|";

    public new bool Equals(object x, object y)
    {
        return object.Equals(x, y);
    }

    public int GetHashCode(object x)
    {
        return x.GetHashCode();
    }

    public object NullSafeGet(IDataReader rs, string[] names, object owner)
    {
        var r = rs[names[0]];
        return r == DBNull.Value 
            ? new List<string>()
            : ((string)r).SplitAndTrim(new [] { delimiter });
    }

    public void NullSafeSet(IDbCommand cmd, object value, int index)
    {
        object paramVal = DBNull.Value;
        if (value != null)
        {
            paramVal = ((IEnumerable<string>)value).Join(delimiter);
        }
        var parameter = (IDataParameter)cmd.Parameters[index];
        parameter.Value = paramVal;
    }

    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;
    }

    public SqlType[] SqlTypes
    {
        get { return new SqlType[] { new StringSqlType() }; }
    }

    public Type ReturnedType
    {
        get { return typeof(IList<string>); }
    }

    public bool IsMutable
    {
        get { return false; }
    }
}

然后定义IList< string>属性为type ="MyApp.DelimitedList，MyApp".

Then define the IList<string> property as type="MyApp.DelimitedList, MyApp".

注意:SplitAndTrim是一个字符串扩展，具有我创建的各种替代.这是核心方法:

NOTE: SplitAndTrim is a string extension with various overrides that I created. Here is the core method:

public static IList<string> SplitAndTrim(this string s, StringSplitOptions options, params string[] delimiters)
    {
        if (s == null)
        {
            return null;
        }
        var query = s.Split(delimiters, StringSplitOptions.None).Select(x => x.Trim());
        if (options == StringSplitOptions.RemoveEmptyEntries)
        {
            query = query.Where(x => x.Trim() != string.Empty);
        }
        return query.ToList();
    }

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