C# 将 IList 转换为列表
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Cast IList to List
提问by Pankaj
I am trying to cast IListtype to Listtype but I am getting error every time.
我正在尝试将IList类型转换为List类型，但每次都会出错。
List<SubProduct> subProducts= Model.subproduct;
Model.subproductreturns IList<SubProduct>.
Model.subproduct返回IList<SubProduct>。
采纳答案by Pbirkoff
Try
尝试
List<SubProduct> subProducts = new List<SubProduct>(Model.subproduct);
or
或者
List<SubProduct> subProducts = Model.subproducts as List<SubProduct>;
回答by Webleeuw
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).
隐式转换失败是因为List<>implements IList，反之亦然。所以你可以说IList<T> foo = new List<T>()，但不能List<T> foo = (some IList-returning method or property)。
回答by Mark Seemann
How about this:
这个怎么样：
List<SubProduct> subProducts = Model.subproduct.ToList();
回答by bluish
In my case I had to do this, because none of the suggested solutions were available:
就我而言，我必须这样做，因为没有任何建议的解决方案可用：
List<SubProduct> subProducts = Model.subproduct.Cast<SubProduct>().ToList();
回答by Hudhaifa Yoosuf
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.
这会将 IList 对象转换为 List 对象。
回答by Ghebrehiywet
This is the best option to cast/convert list of generic object to list of string.
这是将通用对象列表转换/转换为字符串列表的最佳选择。
object valueList;
List<string> list = ((IList)valueList).Cast<object>().Select(o => o.ToString()).ToList();
回答by user11331434
The other answers all recommend to use AddRange with an IList.
其他答案都建议将 AddRange 与 IList 一起使用。
A more elegant solution that avoids the casting is to implement an extension to IList to do the job.
避免强制转换的更优雅的解决方案是实现对 IList 的扩展来完成这项工作。
In VB.NET:
在 VB.NET 中：
<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#:
在 C# 中：
public void AddRange<T>(this ref IList<T> Exttype, IEnumerable<T> ElementsToAdd)
{
foreach (var ele in ElementsToAdd)
{
Exttype.Add(ele);
}
}
回答by JasonLandbridge
If you have an IList containing interfaces, you can cast it like this:
如果你有一个包含接口的 IList，你可以像这样转换它：
List to IList
列表到 IList
List<Foo> Foos = new List<Foo>();
IList<IFoo> IFoos = Foos.ToList<IFoo>();
IList to List
IList到列表
IList<IFoo> IFoos = new List<IFoo>();
List<Foo> Foos = new List<Foo>(IFoos.Select(x => (Foo)x));
This assumes Foohas IFoointerfaced.
这假设Foo已经IFoo接口了。
回答by Golden Lion
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>();
}
