Question

In my project, my data layer keeps a number of List collections to store the last returned data from SQl DB searches. I find myself repeating a lot of code. One in particular is used to see if a data object is already in the database, so that it can be updated instead of added. Here is an example:

public List<ClassA> ListClassA;
public List<ClassB> ListClassB;
    public override bool ContainsClassA(ClassA group)
    {
        if (null == group)
        {
            throw new ArgumentNullException();
        }
        return ListClassA.Where(x => x.ClassA_ID == group.ClassA_ID).ToList().Count > 0;
    }

    public override bool ContainsClassB(ClassB group)
    {
        if (null == group)
        {
            throw new ArgumentNullException();
        }
        return ListClassB.Where(x => x.ClassB_ID == group.ClassB_ID).ToList().Count > 0;
    }

Is there a way in which I can do this using the one function and Generics?
Would I need to rename the index fields so that they match e.g. ClassA_ID and ClassB_ID to ID?

Answer 1

Have both classes implement an interface with an ID property, and then use a generic with a constraint (where T : [your interface name]).

Also,

ListClassA.Where(x => x.ClassA_ID == group.ClassA_ID).ToList().Count > 0

is a bit redundant, you could just use

ListClassA.Any(x => x.ClassA_ID == group.ClassA_ID)