从C＃中的IList访问字段值

Question

I have a IList<T> which has data and i want to access the field value from the IList.

I have written below code to get field value

IList<T> source;
source.FirstOrDefault().Field("ParentID")

I want to access ParentID field value.

But it is giving following error while building the solution:

"'T' does not contain a definition for 'Field' and no extension method 'Field' accepting a first argument of type 'T' could be found (are you missing a using directive or an assembly reference?)"

I have added System.Xml, System.Xml.Linq and System.Collections.Generic assembly, but still it doesn't work. Can anybody help?

Answer 1

Here is some generics 101.

Let's say you had a class named Node , which contained a property named ParentID .

public class Node 
{
    public int ParentId { get; set; }
}

Now you define a list of nodes. Basically an array of objects. In List<T> the T refers to the type of objects in your list. So you would define it as such:

IList<Node> source;

Then you would need to populate your list named source .

And then you could select the ParentId with the code you wrote.

source.FirstOrDefault().Field("ParentID")

Answer 2

将source.FirstOrDefault（）强制转换为适当的类，例如： ((Employee)source.FirstOrDefault()).Field("ParentID")