Question

Given this:

class InvoiceHeader {
    public int InvoiceHeaderId { get; set; }
    IList<InvoiceDetail> LineItems { get; set; }
}

I’m currently using this code to detect if a class has a collection property:

void DetectCollection(object modelSource)
{       
    Type modelSourceType = modelSource.GetType();
    foreach (PropertyInfo p in modelSourceType.GetProperties())
    {
        if (p.PropertyType.IsGenericType &&  p.PropertyType.GetGenericTypeDefinition() == typeof(IList<>))
        {
            System.Windows.Forms.MessageBox.Show(p.Name);
        }
    }
}

Is there a general way to detect if the LineItems is an enumerable type? Some will use other enumerable type (e.g. ICollection), not an IList.

Answer 1

Your code doesn’t actually check if the properties are Enumerable types but if they are generic IList’s. Try this:

if(typeof(IEnumerable).IsAssignableFrom(p.PropertyType))
{
   System.Windows.Forms.MessageBox.Show(p.Name);
}

Or this

if (p.PropertyType.GetInterfaces().Contains(typeof(IEnumerable)))
{
    System.Windows.Forms.MessageBox.Show(p.Name);
}