Question

我有一张Excel表格，其中包含列和列映射列表。

List<Mapping> _mapping

Mapping是一个包含两个字符串的类

public class Mapping
{
    public string ExcelColumn { get; set; } //the excel column name
    public string MapTo { get; set; } //the column in sql database that it maps to
}

基本上，我正在尝试将两个数据集结合起来，类似于SQL WHERE [field1] IN [field2]子句。但我有两个问题：

无法将[]索引应用于Class
EnumerableRowCollection不包含Field

代码：

var allActivity = GetActivity();

using (DataTable excelData = GetExcelDataAsTable()) //get datatable representation of EXCEL SHEET
{
    var excelDataRows = excelData.AsEnumerable();

    //do this for each field mapped
    foreach(Mapping fieldMapping in _mapping)
    {
        var result = from activity in allActivity //where clause contains errors
                     where activity[fieldMapping.MapTo].Contains(excelDataRows.Field<string>(fieldMapping.ExcelColumn))
                     select activity;
    }
}

这是GetActivity()，它返回一个IEnumerable

private IEnumerable<TradeActivity> GetActivity()

Answer 1

想出来......

首先，我们需要能够通过字符串名称引用类属性。将其添加到班级

public object this[string propertyName]
{
    get { return this.GetType().GetProperty(propertyName).GetValue(this, null); }
    set { this.GetType().GetProperty(propertyName).SetValue(this, value, null); }
}

需要隔离其中一个数据集：

var excelColumn = excelData.AsEnumerable().Select(r => r[fieldMapping.ExcelColumn]);

然后执行where子句：

var result = from activity in allActivity
             where excelColumn.Contains(activity[fieldMapping.MapTo])
             select activity;

在LINQ查询中按列名引用DataRows，然后通过与另一个数据集

1 个答案: