Best way to get sub properties using GetProperty

Question

public class Address
{
    public string ZipCode {get; set;}
}

public class Customer
{
    public Address Address {get; set;}
}

how can I access eitther "ZipCode" or "Address.ZipCode" with reflection? For example:

Typeof(Customer).GetProperty("ZipCode")?

Answer 1

You'd need something like:

PropertyInfo addressProperty = typeof(Customer).GetProperty("Address");
ProportyInfo zipCodeProperty = addressProperty.PropertyType.GetProperty("ZipCode");

object address = addressProperty.GetValue(customer, null);
object zipCode = zipCodeProperty.GetValue(address, null);

Basically if you want to take a string "Address.ZipCode" and navigate down it, you need to split it by "." and then call GetProperty on the appropriate type at every step to get the property itself, then PropertyInfo.GetValue to get the next value in the chain. Something like this:

public static object FollowPropertyPath(object value, string path)
{
    Type currentType = value.GetType();

    foreach (string propertyName in path.Split('.'))
    {
        PropertyInfo property = currentType.GetProperty(propertyName);
        value = property.GetValue(value, null);
        currentType = property.PropertyType;
    }
    return value;
}

Call it like this:

object zipCode = FollowPropertyPath(customer, "Address.ZipCode");

Note that this works on the compile-time types of the properties. If you want it to cope with the execution time type (e.g. if customer.Address didn't have a ZipCode property, but the actual type returned by Address did) then change property.PropertyType to property.GetType().

Also note that this doesn't have any error handling etc :)