將數據錶轉換爲列表

Question

public static IList<Task> GetAllTasks() 
    { 
     return _taskSet.Task.ToList<Task>(); 
     // return sampleData.ToList(); 
    } 

我正在將dataTable轉換爲列表，並且出現以下錯誤。如何將表格轉換爲列表。

Error 1 Instance argument: cannot convert from  orkTimeTable.Dataset.TaskSet.TaskDataTable' to 'System.Collections.Generic.IEnumerable<WorkTimeTable.Model.Task>' c:\users\huzaifa.gain\documents\visual studio 2010\Projects\WorkTimeTable\WorkTimeTable\Model\TaskDataService.cs 24 20 WorkTimeTable 

Error 2 'WorkTimeTable.Dataset.TaskSet.TaskDataTable' does not contain a definition for 'ToList' and the best extension method overload 'System.Linq.Enumerable.ToList<TSource>(System.Collections.Generic.IEnumerable<TSource>)' has some invalid arguments c:\users\huzaifa.gain\documents\visual studio 2010\Projects\WorkTimeTable\WorkTimeTable\Model\TaskDataService.cs 24 20 WorkTimeTable 

Answer 1

總有：

List<DataRow> list = dt.AsEnumerable().ToList(); 

或者你可以使用動態或靜態類型爲你的具體情況

Answer 2

嘗試：

public static IList<Task> GetAllTasks() 
{ 
    return _taskSet.Task.AsEnumerable().ToList(); 
} 

Answer 3

這將採取類似的領域從T類中的數據表和填充字段：

public List<T> ToList<T>(this DataTable dt) 
{ 
    List<T> res = new List<T>(); 
    try { 
     if (dt != null && dt.Rows.Count > 0) { 
      object prps = typeof(T).GetProperties; 
      object prpnames = prps.Select((System.Object f) => f.Name).ToList; 
      for (i = 0; i <= dt.Rows.Count - 1; i++) { 
       T Tinst = Activator.CreateInstance(typeof(T)); 
       for (j = 0; j <= dt.Columns.Count - 1; j++) { 
        int prpInd = prpnames.IndexOf(dt.Columns(j).ColumnName); 
        if (prpInd >= 0) { 
         prps(prpInd).SetValue(Tinst, dt(i)(j), null); 
        } 
       } 
       res.Add(Tinst); 
      } 
     } 
    } catch (Exception ex) { 
     PromptMsg(ex); 
    } 
    return res; 
} 

用法：如果我們有名字，姓氏，othercolumns一個DataTable ...和

public class classSample{ 

    private string _FirstName; 
    public string FirstName{ 
     get { 
      return _FirstName; 
     } 
     set { 
      _FirstName = value; 
     } 
    } 

    private string _LastName; 
    public string LastName{ 
     get { 
      return _LastName; 
     } 
     set { 
      _LastName = value; 
     } 
    } 

} 

因此，這將返回classSample的列表：

someDT.ToList<classSample>(); 

Answer 4

public static IList<Task> GetAllTasks() 
    { 
     List<Task> taskList = new List<Task>(); 
     foreach (TaskSet.TaskRow r in _taskSet.Task.AsEnumerable()) 
      taskList.Add(new WorkTimeTable.Model.Task() 
          { 
           Name = r.Name, Description = r.Description, ToDateTime = r.ToDate, FromDateTime = r.FromDate, TotalTime = r.TimeSpan 
          }); 
     return taskList; 
    } 

Answer 5

用於以下類將數據錶轉換爲列表。

public static class Helper 
{ 



    public static List<T> DataTableToList<T>(this DataTable dataTable) where T : new() 
    { 
     var dataList = new List<T>(); 

     //Define what attributes to be read from the class 
     const System.Reflection.BindingFlags flags = System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance; 

     //Read Attribute Names and Types 
     var objFieldNames = typeof(T).GetProperties(flags).Cast<System.Reflection.PropertyInfo>(). 
      Select(item => new 
      { 
       Name = item.Name, 
       Type = Nullable.GetUnderlyingType(item.PropertyType) ?? item.PropertyType 
      }).ToList(); 

     //Read Datatable column names and types 
     var dtlFieldNames = dataTable.Columns.Cast<DataColumn>(). 
      Select(item => new 
      { 
       Name = item.ColumnName, 
       Type = item.DataType 
      }).ToList(); 

     foreach (DataRow dataRow in dataTable.AsEnumerable().ToList()) 
     { 
      var classObj = new T(); 

      foreach (var dtField in dtlFieldNames) 
      { 
       System.Reflection.PropertyInfo propertyInfos = classObj.GetType().GetProperty(dtField.Name); 

       var field = objFieldNames.Find(x => x.Name == dtField.Name); 

       if (field != null) 
       { 

        if (propertyInfos.PropertyType == typeof(DateTime)) 
        { 
         propertyInfos.SetValue 
         (classObj, convertToDateTime(dataRow[dtField.Name]), null); 
        } 
        else if (propertyInfos.PropertyType == typeof(Nullable<DateTime>)) 
        { 
         propertyInfos.SetValue 
         (classObj, convertToDateTime(dataRow[dtField.Name]), null); 
        } 
        else if (propertyInfos.PropertyType == typeof(int)) 
        { 
         propertyInfos.SetValue 
         (classObj, ConvertToInt(dataRow[dtField.Name]), null); 
        } 
        else if (propertyInfos.PropertyType == typeof(long)) 
        { 
         propertyInfos.SetValue 
         (classObj, ConvertToLong(dataRow[dtField.Name]), null); 
        } 
        else if (propertyInfos.PropertyType == typeof(decimal)) 
        { 
         propertyInfos.SetValue 
         (classObj, ConvertToDecimal(dataRow[dtField.Name]), null); 
        } 
        else if (propertyInfos.PropertyType == typeof(String)) 
        { 
         if (dataRow[dtField.Name].GetType() == typeof(DateTime)) 
         { 
          propertyInfos.SetValue 
          (classObj, ConvertToDateString(dataRow[dtField.Name]), null); 
         } 
         else 
         { 
          propertyInfos.SetValue 
          (classObj, ConvertToString(dataRow[dtField.Name]), null); 
         } 
        } 
        else 
        { 

         propertyInfos.SetValue 
          (classObj, Convert.ChangeType(dataRow[dtField.Name], propertyInfos.PropertyType), null); 

        } 
       } 
      } 
      dataList.Add(classObj); 
     } 
     return dataList; 
    } 

    private static string ConvertToDateString(object date) 
    { 
     if (date == null) 
      return string.Empty; 

     return date == null ? string.Empty : Convert.ToDateTime(date).ConvertDate(); 
    } 

    private static string ConvertToString(object value) 
    { 
     return Convert.ToString(ReturnEmptyIfNull(value)); 
    } 

    private static int ConvertToInt(object value) 
    { 
     return Convert.ToInt32(ReturnZeroIfNull(value)); 
    } 

    private static long ConvertToLong(object value) 
    { 
     return Convert.ToInt64(ReturnZeroIfNull(value)); 
    } 

    private static decimal ConvertToDecimal(object value) 
    { 
     return Convert.ToDecimal(ReturnZeroIfNull(value)); 
    } 

    private static DateTime convertToDateTime(object date) 
    { 
     return Convert.ToDateTime(ReturnDateTimeMinIfNull(date)); 
    } 

    public static string ConvertDate(this DateTime datetTime, bool excludeHoursAndMinutes = false) 
    { 
     if (datetTime != DateTime.MinValue) 
     { 
      if (excludeHoursAndMinutes) 
       return datetTime.ToString("yyyy-MM-dd"); 
      return datetTime.ToString("yyyy-MM-dd HH:mm:ss.fff"); 
     } 
     return null; 
    } 
    public static object ReturnEmptyIfNull(this object value) 
    { 
     if (value == DBNull.Value) 
      return string.Empty; 
     if (value == null) 
      return string.Empty; 
     return value; 
    } 
    public static object ReturnZeroIfNull(this object value) 
    { 
     if (value == DBNull.Value) 
      return 0; 
     if (value == null) 
      return 0; 
     return value; 
    } 
    public static object ReturnDateTimeMinIfNull(this object value) 
    { 
     if (value == DBNull.Value) 
      return DateTime.MinValue; 
     if (value == null) 
      return DateTime.MinValue; 
     return value; 
    } 
} 

您可以將您的數據表中列出

var mytbl=dt.DataTableToList();