SSRS如何在表中显示动态列数？

Question

我有一个xml数据源，它返回一个像这样的xml：

<ArrayOfAttendanceStudentExchangeModel xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <AttendanceStudentExchangeModel>
        <Counter>1</Counter>
        <FatherLastName>Roque</FatherLastName>
        <MotherLastName>Parisaca</MotherLastName>
        <Names>Sergio Gustavo</Names>
        <Attendances>
            <string>P</string>
            <string>F</string>
            <string>F</string>
            <string>P</string>
            <string>P</string>
            <string>P</string>
            <string>P</string>
            <string>P</string>
        </Attendances>
    </AttendanceStudentExchangeModel>
</ArrayOfAttendanceStudentExchangeModel>

web api方法将某种类型的Collection作为XMl返回。

public class AttendanceStudentExchangeModel
{
    public int Counter { get; set; }
    public string FatherLastName { get; set; }
    public string MotherLastName { get; set; }
    public string Names { get; set; }
    public string[] Attendances { get; set; }
}

[HttpGet]
public HttpResponseMessage GetAttendanceSheet(string codigoDocente, int codigoHorario, int periodCode)
{
    {
        AttendanceSheetService attendanceSheetBuilder = new AttendanceSheetService();
        var attendanceSheetResult = attendanceSheetBuilder.GetAttendanceSheetCollection(codigoDocente, codigoHorario, periodCode);

        var content = new ObjectContent<List<AttendanceStudentExchangeModel>>(attendanceSheetResult, Configuration.Formatters.XmlFormatter);
        return new HttpResponseMessage()
        {
            Content = content
        };
    }
}

数据集中的查询：

<Query>
    <ElementPath>
        ArrayOfAttendanceStudentExchangeModel {} /AttendanceStudentExchangeModel
    </ElementPath>
</Query>

我手动定义了字段：

结果：

结果所需：

出勤人数（Asistencias）可能因查询而异。

我怎样才能做到这一点？