Silverlight Bing Maps Control and Drag & Drop

David Justice — Sat, 17 Apr 2010 22:57:00 GMT

I was recently asked to build up a Silverlight tool to show a file full of addresses on a map. I decided to use the Silverlight bing maps control and I must say I was not disappointed with it's functionality. It ended up being extremely simple. The tools used to create this were VS2010, Silverlight 4, Bing maps Silverlight control, and the Bing maps web services.

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Genetic Algorithm -- Add Ur Own Func :)

David Justice — Mon, 29 Jun 2009 08:34:00 GMT

Hi again,

I was a little bored this weekend and needed to add in some GA functionality to a side project. I felt like it would be best to create a simple executer to deal with the iterative behavior of a genetic algorithm. The executer take in funcs provided by the consumer and executes based on a simple iterative model. Below is what I came up with. Cheers!

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.Net 4.0 Reflection vs. Dynamics vs. Property Setting With Times

David Justice — Fri, 26 Jun 2009 16:26:00 GMT

Today I found my self hanging out after a sprint review with my partner in crime Kevin Rohling. TFS was down (not tfs's fault, but some other freak accident...) and I hadn't installed VS 2010 yet, so it seemed like the perfect time to do such things. I got everything up and running, and Kevin and I got into a discussion about Dynamics & performance. We made a quick lunch bet on which is faster, reflection or dynamics for simply setting a property. I figured reflection would be quicker, while Kevin thought dynamics would be faster. Well, I owe him lunch now. The code is below.

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MetaTable Expression Builder for Fetching Any Object Via Collection of Primary Keys

David Justice — Tue, 04 Nov 2008 10:53:00 GMT

Basically, I wanted to build a method that gets an object from a data context whatever the primary key may look like, and whatever type that object may be.  I wrote this code a little while ago when I was exploring the DynamicData libs.  I was checking out some of the code in the libs, and noticed a very slick way one of devs was building expressions to grab back a data item based on a single key ID.  I thought the idea of building up the expression completely ROCKED, but I wanted to expand it out to include composite primary keys.  Below is my implementation of the composite primary key object fetcher.  Hopefully, it will make your life a little easier.
 
(Needed to grab the MetaModel class)
 
using System.Web.DynamicData;
 
(Create a new MetaModel for your Context or Contexts -- make sure they are only registered once!!  This can be an issue if you put this code in a static constructor, and you happen to have a generic class.  That would cause the code to get executed each time you specify a new generic argument for type construction (sry, I digress))

 
Model = new MetaModel();
Model.RegisterContext(typeof([Your Context Type]));
 
(Get your meta table based on the type from your registered context -- need the metadata about the table to figure out the keys)

protected static MetaTable GetMetaTable<T>()
{
    return dataModelMetaModel.GetTable(typeof (T));
}

(This is where the heavy lifting occurs.  I commented what is going on.  There is not much more to say.  Enjoy!)
 

private static T FetchObject<T>(MetaTable metatable, IDictionary<string, object> pks)
    where T : class
{
    IQueryable query = metatable.GetQuery();
 
    //build linq expression tree for where clause
    ParameterExpression entityparam = Expression.Parameter(metatable.EntityType, "e");
    List<Expression> internalExpressons = new List<Expression>();
    Expression equalexpression;
    foreach (MetaColumn member in metatable.PrimaryKeyColumns)
    {
        //convert primary key to proper type
        PropertyInfo columnpropertyinfo = member.EntityTypeProperty;
        MemberExpression columnexpresson = Expression.MakeMemberAccess(entityparam, columnpropertyinfo);
        internalExpressons.Add(Expression.Equal(columnexpresson, Expression.Constant(pks[member.Name])));
    }
 
    // build up the primary key expressions
    if (internalExpressons.Count > 1)
    {
        equalexpression = Expression.And(internalExpressons[0], internalExpressons[1]);
        for (int i = 2; i < internalExpressons.Count; i++)
        {
            equalexpression = Expression.And(equalexpression, internalExpressons);
        }
    }
    else
    {
        equalexpression = internalExpressons[0];
    }
 
    // Create the where clause
    LambdaExpression wherelambda = Expression.Lambda(equalexpression, entityparam);
    MethodCallExpression wherecall = Expression.Call(typeof (Queryable), "Where", new[] {metatable.EntityType},
                                                     query.Expression, wherelambda);
    query = query.Provider.CreateQuery(wherecall);
 
    // Call FirstOrDefault to make sure the connection is closed when finished
    // saw some connections staying open when just grabbing the first object.
    return query.Cast<T>().FirstOrDefault();
}
 
Twitter: @DavidJustice

I Can't Believe That Worked : C#

Silverlight Bing Maps Control and Drag & Drop

Genetic Algorithm -- Add Ur Own Func :)

.Net 4.0 Reflection vs. Dynamics vs. Property Setting With Times

MetaTable Expression Builder for Fetching Any Object Via Collection of Primary Keys