Filtering on template list with property name as string

Question

Hi I have to apply filter on generic class. The sample class is as follows

public class Sample
{
    List sourceList = new List();         


        

Answer 1

You can use Reflection for retrieving the property value and you can use a simple switch statement upon the operator to perform the filtering:

public IEnumerable ApplyFilter(string propertyName, EnumOperator op, object value)
{
    foreach (T item in sourceList)
    {
        object propertyValue = GetPropertyValue(item, propertyName);
        if (ApplyOperator(item, propertyValue, op, value)
        {
            yield return item;
        }
    }
}

private object GetPropertyValue(object item, string propertyName)
{
    PropertyInfo property = item.GetType().GetProperty(propertyName);
    //TODO handle null
    return property.GetValue();
}

private bool ApplyOperator(object propertyValue, EnumOperator op, object value)
{
    switch (op)
    {
        case EnumOperator.Equals:
            return propertyValue.Equals(value);
        //TODO other operators
        default:
            throw new UnsupportedEnumException(op);
    }
}

(An optimization would be to look up the PropertyInfo once outside of the loop.)