C#List-to-DataTable扩展方法未检索属性

Question

我想将KNMOLijst类型的ObservableCollection转换为DataTable。我为它找到了一个扩展方法，但它没有检索我的属性？

扩展方式：

public static class ListToDataTable
{
public static DataTable ToDataTable<T>(this IList<T> items)
{
DataTable dataTable = new DataTable(typeof(T).Name);
//Get all the properties
PropertyInfo[] Props = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance);
foreach (PropertyInfo prop in Props)
{
//Defining type of data column gives proper data table 
var type = (prop.PropertyType.IsGenericType && prop.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>) ? Nullable.GetUnderlyingType(prop.PropertyType) : prop.PropertyType);
//Setting column names as Property names
dataTable.Columns.Add(prop.Name, type);
}
foreach (T item in items)
{
var values = new object[Props.Length];
for (int i = 0; i < Props.Length; i++)
{
//inserting property values to datatable rows
values[i] = Props[i].GetValue(item, null);
}
dataTable.Rows.Add(values);
}
//put a breakpoint here and check datatable
return dataTable;
}
}

下面的代码没有检索任何属性，我也试图将非公开成员包括在绑定标记中，但这似乎对我不起作用

//Get all the properties
PropertyInfo[] Props = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance);

这是它收到的KNMOLijst类型：

public class KNMOLijst
{
public string VoorLetters { get; set; }
public string Voornaam { get; set; }
public string TussenVoegsel { get; set; }
public string Achternaam { get; set; }
public string Geslacht { get; set; }
public DateTime GeboorteDatum { get; set; }
public string InstrumentNaam { get; set; }
public KNMOLijst()
{
}
}

我确保这些房产是公开的。

这是扩展方法接收的列表。

generatedList.Add(new KNMOLijst()
{
VoorLetters = (string)(row["VoorLetters"]),
Voornaam = (string)(row["Voornaam"]),
TussenVoegsel = (string)(row["TussenVoegsel"]),
Achternaam = (string)row["Achternaam"],
Geslacht = (string)row["Geslacht"],
GeboorteDatum = (DateTime)row["GeboorteDatum"],
InstrumentNaam = (string)row["InstrumentNaam"]
});

调用ToDataTable方法的视图模型。

public class SecretarisViewModel : BaseViewModel
{
private readonly SecretarisBLL secretarisBll;
private ObservableCollection<object> generatedList;
public ObservableCollection<object> GeneratedList
{
get { return generatedList; }
set
{
generatedList = value;
NotifyPropertyChanged();
}
}
private DataTable generatiedDataTable;
public DataTable GeneratedDataTable
{
get => generatiedDataTable;
set
{
generatiedDataTable = value;
NotifyPropertyChanged();
}
}
public SecretarisViewModel()
{
secretarisBll = new SecretarisBLL();
GeneratedList = new ObservableCollection<object>();
generatiedDataTable = new DataTable();
}
public async Task GetKNMOList()
{
var dataset = await secretarisBll.GetKNMOList();
foreach (DataRow row in dataset.Tables[0].Rows)
{
generatedList.Add(new KNMOLijst()
{
VoorLetters = (string)(row["VoorLetters"]),
Voornaam = (string)(row["Voornaam"]),
TussenVoegsel = (string)(row["TussenVoegsel"]),
Achternaam = (string)row["Achternaam"],
Geslacht = (string)row["Geslacht"],
GeboorteDatum = (DateTime)row["GeboorteDatum"],
InstrumentNaam = (string)row["InstrumentNaam"]
});
}
GeneratedDataTable = generatedList.ToDataTable();
}
}

为什么它无法获取我的列表的属性？

Answer 1

生成的列表是CCD_ 1，所以我认为，如果我在其中添加一个新的KNMOLijst行，它会是KNMOLijst类型吗？

否，如果列表的类型为ObservableCollection<object>，则T是没有公共属性的System.Object。所以让它成为ObservableCollection<KNMOLijst>。

如果你不能做到这一点，请修改方法，从第一项中派生类型：

public static DataTable ToDataTable<T>(this IList<T> items)
{
Type type = items.FirstOrDefault()?.GetType();
if (type == null)
throw new InvalidOperationException("The properties are derived from the first item, so the list must not be empty");
DataTable dataTable = new DataTable(type.Name);
//Get all the properties
PropertyInfo[] Props = type.GetProperties(BindingFlags.Public | BindingFlags.Instance);
// ...
}

顺便说一句，这种行为(在空列表上抛出InvalidOperationException(与CopyToDataTable类似，后者也做同样的事情。它还需要使用反射来获取列。