public static IList<Task> GetAllTasks()
{
return _taskSet.Task.ToList<Task>();
// return sampleData.ToList();
}
我正在将dataTable转换为列表，我收到以下错误。我怎样才能将表转换为List。
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
答案 0 :(得分：1)
始终：
List<DataRow> list = dt.AsEnumerable().ToList();
或者您可以为特定情况使用动态或静态类型
答案 1 :(得分：1)
尝试：
public static IList<Task> GetAllTasks()
{
return _taskSet.Task.AsEnumerable().ToList();
}
答案 2 :(得分：1)
这将采用T类中数据表和填充字段的类似字段：
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：如果我们有一个包含FirstName，LastName，othercolumns ...和
的数据表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，这将返回classSample列表：
someDT.ToList<classSample>();
答案 3 :(得分：1)
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;
}
答案 4 :(得分：0)
使用以下类将数据表转换为列表。
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;
}
}
您可以将数据表转换为列表
var mytbl=dt.DataTableToList();