列表

我试图把 IList类型转换成 List类型,但是每次都出错。

List<SubProduct> subProducts= Model.subproduct;

返回 IList<SubProduct>

141371 次浏览
List<SubProduct> subProducts= (List<SubProduct>)Model.subproduct;

The implicit conversion failes because List<> implements IList, not viceversa. So you can say IList<T> foo = new List<T>(), but not List<T> foo = (some IList-returning method or property).

Try

List<SubProduct> subProducts = new List<SubProduct>(Model.subproduct);

or

List<SubProduct> subProducts = Model.subproducts as List<SubProduct>;

How about this:

List<SubProduct> subProducts = Model.subproduct.ToList();

In my case I had to do this, because none of the suggested solutions were available:

List<SubProduct> subProducts = Model.subproduct.Cast<SubProduct>().ToList();
List<ProjectResources> list = new List<ProjectResources>();
IList<ProjectResources> obj = `Your Data Will Be Here`;
list = obj.ToList<ProjectResources>();

This Would Convert IList Object to List Object.

This is the best option to cast/convert list of generic object to list of string.

object valueList;
List<string> list = ((IList)valueList).Cast<object>().Select(o => o.ToString()).ToList();

The other answers all recommend to use AddRange with an IList.

A more elegant solution that avoids the casting is to implement an extension to IList to do the job.

In VB.NET:

<Extension()>
Public Sub AddRange(Of T)(ByRef Exttype As IList(Of T), ElementsToAdd As IEnumerable(Of T))
For Each ele In ElementsToAdd
Exttype.Add(ele)
Next
End Sub


And in C#:

public void AddRange<T>(this ref IList<T> Exttype, IEnumerable<T> ElementsToAdd)
{
foreach (var ele in ElementsToAdd)
{
Exttype.Add(ele);
}
}

If you have an IList containing interfaces, you can cast it like this:

List to IList

List<Foo> Foos = new List<Foo>();
IList<IFoo> IFoos = Foos.ToList<IFoo>();

IList to List

IList<IFoo> IFoos = new List<IFoo>();
List<Foo> Foos = new List<Foo>(IFoos.Select(x => (Foo)x));

This assumes Foo has IFoo interfaced.

    public async Task<List<TimeAndAttendanceShift>> FindEntitiesByExpression(Expression<Func<TimeAndAttendanceShift, bool>> predicate)
{
IList<TimeAndAttendanceShift> result = await _dbContext.Set<TimeAndAttendanceShift>().Where(predicate).ToListAsync<TimeAndAttendanceShift>();


return result.ToList<TimeAndAttendanceShift>();
}