将DataTable转换为IEnumerable <T>

Question

我正在尝试将DataTable转换为IEnumerable.其中T是我创建的自定义类型.我知道我可以通过创建一个List来实现它,但我认为使用IEnumerable有一种更流畅的方法.这就是我现在拥有的.

    private IEnumerable<TankReading> ConvertToTankReadings(DataTable dataTable)
    {
        var tankReadings = new List<TankReading>();
        foreach (DataRow row in dataTable.Rows)
        {
            var tankReading = new TankReading
                                  {
                                      TankReadingsID = Convert.ToInt32(row["TRReadingsID"]),
                                      TankID = Convert.ToInt32(row["TankID"]),
                                      ReadingDateTime = Convert.ToDateTime(row["ReadingDateTime"]),
                                      ReadingFeet = Convert.ToInt32(row["ReadingFeet"]),
                                      ReadingInches = Convert.ToInt32(row["ReadingInches"]),
                                      MaterialNumber = row["MaterialNumber"].ToString(),
                                      EnteredBy = row["EnteredBy"].ToString(),
                                      ReadingPounds = Convert.ToDecimal(row["ReadingPounds"]),
                                      MaterialID = Convert.ToInt32(row["MaterialID"]),
                                      Submitted = Convert.ToBoolean(row["Submitted"]),
                                  };
            tankReadings.Add(tankReading);
        }
        return tankReadings.AsEnumerable();
    }

关键部分是我创建一个List然后使用AsEnumerable()返回它.

Answer 1

还有一个名为"AsEnumerable()"的DataSetExtension方法(在System.Data中),它接受一个DataTable并返回一个Enumerable.有关更多详细信息,请参阅MSDN文档,但它基本上如下所示:

dataTable.AsEnumerable()

缺点是它枚举了DataRow,而不是你的自定义类."Select()"LINQ调用可以转换行数据,但是:

private IEnumerable<TankReading> ConvertToTankReadings(DataTable dataTable)
{
    return dataTable.AsEnumerable().Select(row => new TankReading      
            {      
                TankReadingsID = Convert.ToInt32(row["TRReadingsID"]),      
                TankID = Convert.ToInt32(row["TankID"]),      
                ReadingDateTime = Convert.ToDateTime(row["ReadingDateTime"]),      
                ReadingFeet = Convert.ToInt32(row["ReadingFeet"]),      
                ReadingInches = Convert.ToInt32(row["ReadingInches"]),      
                MaterialNumber = row["MaterialNumber"].ToString(),      
                EnteredBy = row["EnteredBy"].ToString(),      
                ReadingPounds = Convert.ToDecimal(row["ReadingPounds"]),      
                MaterialID = Convert.ToInt32(row["MaterialID"]),      
                Submitted = Convert.ToBoolean(row["Submitted"]),      
            });
}

Answer 2

该实现没有错.您可以给yield关键字一个镜头,看看你喜欢它:

private IEnumerable<TankReading> ConvertToTankReadings(DataTable dataTable)
    {
        foreach (DataRow row in dataTable.Rows)
        {
            yield return new TankReading
                                  {
                                      TankReadingsID = Convert.ToInt32(row["TRReadingsID"]),
                                      TankID = Convert.ToInt32(row["TankID"]),
                                      ReadingDateTime = Convert.ToDateTime(row["ReadingDateTime"]),
                                      ReadingFeet = Convert.ToInt32(row["ReadingFeet"]),
                                      ReadingInches = Convert.ToInt32(row["ReadingInches"]),
                                      MaterialNumber = row["MaterialNumber"].ToString(),
                                      EnteredBy = row["EnteredBy"].ToString(),
                                      ReadingPounds = Convert.ToDecimal(row["ReadingPounds"]),
                                      MaterialID = Convert.ToInt32(row["MaterialID"]),
                                      Submitted = Convert.ToBoolean(row["Submitted"]),
                                  };
        }

    }

也AsEnumerable没有必要,因为List<T>已经是IEnumerable<T>