Value Object and its collection

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Value Object and its collection

Here's a nifty way to build a Value Object for consumption across your app and then have access to each type as a collection.

First the test:

        [Test]
        public void CanLoadStreetTypesList()
        {
            IList<StreetTypes> types = StreetTypes.ALL;
            foreach(StreetTypes type in types)
            {
                Console.Out.WriteLine(type.Name + " - " + type.Abbreviation);
            }
            Assert.IsTrue(types.Count>0);
        }

So basically I want a list of all the types of a StreetTYpes Value object.

Here's my StreetTypes VO :

    public sealed class StreetTypes
    {
        private string _name;
        private string _abbreviation;
 
        public string Name
        {
            get { return _name; }
        }
 
        public string Abbreviation
        {
            get { return _abbreviation; }
        }
 
        private StreetTypes()
        {
        }
        private StreetTypes(string name, string abbreviation)
        {
            _name = name;
            _abbreviation = abbreviation;
        }
        private static IList<T> All<T>(T obj)
        {
            IList<T> types = new List<T>();
            FieldInfo[] fields = typeof(T).GetFields(BindingFlags.Static | BindingFlags.Public);
            foreach (FieldInfo field in fields)
            {
                if (field.FieldType.Equals(typeof(T)))
                {
                    types.Add((T)field.GetValue(obj));
                }
            }
 
            return types;
        }
 
        public static readonly StreetTypes ACCESS_ROAD = new StreetTypes("Access Road", "AcRd");
        public static readonly StreetTypes ALLEY = new StreetTypes("Alley", "Aly");
        public static readonly StreetTypes AVENUE = new StreetTypes("Avenue", "Ave");
        public static readonly StreetTypes BOULEVARD = new StreetTypes("Boulevard", "Blvd");
        public static readonly StreetTypes BRIDGE = new StreetTypes("Bridge", "Brg");
        public static readonly StreetTypes CIRCLE = new StreetTypes("Circle", "Cir");
        public static readonly StreetTypes COURT = new StreetTypes("Court", "Ct");
        public static readonly StreetTypes CUTOFF = new StreetTypes("Cutoff", "Cto");
        public static readonly StreetTypes DRIVE = new StreetTypes("Drive", "Dr");
        public static readonly StreetTypes EXPRESSWAY = new StreetTypes("Expressway", "Expy");
        public static readonly StreetTypes EXTENSION = new StreetTypes("Extension", "Ext");
        public static readonly StreetTypes FREEWAY = new StreetTypes("Freeway", "Fwy");
        public static readonly StreetTypes HIGHWAY = new StreetTypes("Highway", "Hwy");
        public static readonly StreetTypes KEY = new StreetTypes("Key", "Ky");
        public static readonly StreetTypes LANE = new StreetTypes("Lane", "Ln");
        public static readonly StreetTypes LOOP = new StreetTypes("Loop", "Loop");
        public static readonly StreetTypes OVERPASS = new StreetTypes("Overpass", "Opas");
        public static readonly StreetTypes PARK = new StreetTypes("Park", "Park");
        public static readonly StreetTypes PARKWAY = new StreetTypes("Parkway", "Pkwy");
        public static readonly StreetTypes RAMP = new StreetTypes("Ramp", "Ramp");
        public static readonly StreetTypes ROAD = new StreetTypes("Road", "Rd");
        public static readonly StreetTypes RISE = new StreetTypes("Rise", "Rise");
        public static readonly StreetTypes STREET = new StreetTypes("Street", "St");
        public static readonly StreetTypes TERRACE = new StreetTypes("Terrace", "Ter");
        public static readonly StreetTypes TRAIL = new StreetTypes("Trail", "Trl");
        public static readonly StreetTypes TUNNEL = new StreetTypes("Tunnel", "Tunl");
        public static readonly StreetTypes WALK = new StreetTypes("Walk", "Walk");
        public static readonly StreetTypes WAY = new StreetTypes("Way", "Way");
        public static IList<StreetTypes> ALL
        {
            get
            {
                return All<StreetTypes>(new StreetTypes());
            }
        }
 
 
    }

The ALL property returns a collection that uses reflection in the embedded All(T obj) method. This All method is great because I can use it to reflect on any similar Value Object that wants to spit out a collection of all iits static type/fields. Now when I add a new streettype (since that happens so much), the collection will 'reflect' the changes without relying on me adding it to the collection.

Print posted @ Friday, August 11, 2006 12:39 PM

Feedback

# re: Value Object and its collection

Mike,
Very slick. My only improvements would be:

// Make Street Types as immutable as possible
private readonly string _name;
private readonly string _abbreviation;

// Cache All
private static IList<StreetTypes> _all;

public static IList<StreetTypes> All
{
get
{
if( _all == null )
//...Only reflect the first time
return _all;
}
}

// Override equals, gethashcode, ==, !=

and move All<T> to a static Utility class.

-Bill 8/14/2006 4:40 AM | Bill Pierce

# re: Value Object and its collection

Thanks Bill...I got a similar tip from someone else and implemented...I appreciate the feedback! 8/14/2006 5:11 AM | Mike

Mike Nichols - SonOfNun Technology