为什么此WPF数据网格显示从具有date数据类型的SQL Server数据库导入数据的时间？(Why is this WPF datagrid showing a time when importing data from SQL Server database with date datatype?)

 在这一行： 
 
IEnumerable<int> listOfValues = 
                       property.GetValue(transformedData, null) as IEnumerable<int>;
 
 您正在尝试在List<SomeModel>对象上检索ViewValue属性的值，但List<SomeModel>没有ViewValue属性。 你可以做的一件事是： 
 
IEnumerable<int> listOfValues = 
                       transformedData.Select(i => (int)property.GetValue(i, null));
 
 但更清洁的解决方案是完全避免反射，因为这里不需要： 
 
interface IViewValue
{
    int ViewValue { get; set; }
}

public class SomeViewModel : IViewValue
{
    public int ViewValue { get; set; }
}

private int SumValues<T, TRes>(IEnumerable<T> data, Func<T, TRes> transformation)
                                            where TRes : IViewValue
{
    var transformedData = data.Select(transformation);
    IEnumerable<int> listOfValues = transformedData.Select(i => i.ViewValue);
    var sum = listOfValues.Sum();

    return sum;
}

In this line:
 
IEnumerable<int> listOfValues = 
                       property.GetValue(transformedData, null) as IEnumerable<int>;
 
You're trying to retrieve the value of the ViewValue property on a List<SomeModel> object, but List<SomeModel> doesn't have a ViewValue property. One thing you could do is this:
 
IEnumerable<int> listOfValues = 
                       transformedData.Select(i => (int)property.GetValue(i, null));
 
But a much cleaner solution would be to avoid reflection entirely as it's not needed here:
 
interface IViewValue
{
    int ViewValue { get; set; }
}

public class SomeViewModel : IViewValue
{
    public int ViewValue { get; set; }
}

private int SumValues<T, TRes>(IEnumerable<T> data, Func<T, TRes> transformation)
                                            where TRes : IViewValue
{
    var transformedData = data.Select(transformation);
    IEnumerable<int> listOfValues = transformedData.Select(i => i.ViewValue);
    var sum = listOfValues.Sum();

    return sum;
}