A better way of evaluating two objects

Question

I'm struggling to find a better way of evaluating two objects that may or may not be a list of strings.

I feel that there must be a better way of doing the below. Does anyone have some advice that can help me please?

I'm getting the objects from a web service, so there is no way of knowing beforehand what type of objects they are.

private bool EvaluateDataLists(object dataLeft, object dataRight)
{
    bool isDataLeftList = dataLeft is List<string>;
    bool isDataRightList = dataRight is List<string>;

    if (isDataLeftList && !isDataRightList)
    {
        foreach (var entry in dataLeft as List<string>)
        {
            if (Expression.Evaluate(entry, dataRight.ToString(), valueOperator))
                return true;
        }
    }
    else if (!isDataLeftList && isDataRightList)
    {
        foreach (var entry in dataRight as List<string>)
        {
            if (Expression.Evaluate(dataLeft.ToString(), entry, valueOperator))
                return true;
        }
    }
    else if (isDataLeftList && isDataRightList)
    {
        foreach (var leftEntry in dataLeft as List<string>)
        {
            foreach (var rightEntry in dataRight as List<string>)
            {
                if (Expression.Evaluate(leftEntry, rightEntry, valueOperator))
                    return true;
            }
        }
    }

    return false;
}

Answer 1

If I have understood your question/code correctly does this solve your problem or help?

private bool EvaluateDataLists(object dataLeft, object dataRight)
{
    List<string> left = (dataLeft is List<string>) ? dataLeft as List<string> : new List<string> { dataLeft.ToString() };
    List<string> right = (dataRight is List<string>) ? dataRight as List<string> : new List<string> { dataRight.ToString() };

    foreach (string item in left)
    {
        if (right.Where(r => Expression.Evaluate(item, r, valueOperator)).Count > 0)
        {
            return true;
        }
    }
    return false;
}

If so, I would probably refactor the two halves of the method into two separate methods - one to ensure you have lists of strings, and a second do iterate and compare