How to: Access the Report Parameters Object in Calculated Fields Expressions 如何：在计算字段表达式中访问报表参数对象

This topic describes how you can access data of a report parameters object (inherited from ReportParametersObjectBase and specified using IReportDataV2.ParametersObjectType) in calculated field expressions.

本主题介绍如何在计算字段表达式中访问报表参数对象的数据（从报表参数对象库继承并使用 IReportDataV2.参数对象类型指定）。

Note 注意

The approach described in this topic is not supported by the Mobile platform.

移动平台不支持本主题中描述的方法。

 

Override the Parameters Object's ToString method.

覆盖参数对象的 ToString 方法。

public class DemoParameters : ReportParametersObjectBase {
    // ...
    public override string ToString() {
        return City;
    }
}

As a result, you can refer to the ToString result with the "[Parameters.XafReportParametersObject]" expression, e.g.:

因此，您可以使用"[参数.XafReport参数对象]" 表达式引用 ToString 结果，例如：

Concat([Full Name],' from ', [Parameters.XafReportParametersObject])

Alternatively, you can create a report script, handle the GetValue event of a certain field and then access a parameter value as demonstrated in the How to: Access the Report Parameters Object in Report Scripts topic.

或者，您可以创建报表脚本，处理特定字段的 GetValue 事件，然后访问参数值，如"如何：在报表脚本中访问报表参数对象"主题中所示。

private void calculatedFieldCity_GetValue(object sender, DevExpress.XtraReports.UI.GetValueEventArgs e) {
    DevExpress.XtraReports.Parameters.Parameter param =
            (DevExpress.XtraReports.Parameters.Parameter)
                ((DevExpress.XtraReports.UI.XtraReport)e.Report).Parameters["XafReportParametersObject"];
    if (param != null) {
        ReportV2Demo.Module.BusinessObjects.Contact contact = 
        (ReportV2Demo.Module.BusinessObjects.Contact)e.Row;
        ReportV2Demo.Module.Reports.DemoParameters xafParameter =
            (ReportV2Demo.Module.Reports.DemoParameters)param.Value;
        e.Value = contact.FullName + " from " + xafParameter.City;
    }
}