Doing Notes for my Boise Code Camp Presentation

I presented this afternoon at the Boise Code Camp. All in all, it went OK. However, I had a really rough start. I am proud that I was able to brush it off and go on (I even got a couple of complements). It is important to continue on when I am bombing and debug my performance after the ordeal is over. After an Improv show (at least at the Blue Door Theatre), the performers do “Notes”.

I have observed that many code camp presentations start out scripted and eventually move into improv. It isn’t like a short games or a Harold where it can go in any direction; more like a Larry David script that has a story arc but no written dialog. This pivot usually occurs when the first question is asked. The presentation becomes a dialog that follows the outline of the presentation. I usually am good at engaging the audience in that dialog; I guess I am good at crowd work.

Rough Start

I had a lot of trouble getting started. I umed, I spoke too fast, spoke in a single note, I left stuff off (I didn’t even properly introduce myself), it took too long to get into a groove. My first 5 minutes were really weak. I didn’t rehearse that part of the presentation enough. I didn’t speak the words out loud enough. The first 5 minutes sets the pace for the rest of the show.

Improvements in Other Areas

I felt good about the rest of the talk. Last time out I had trouble talking and coding at the same time; this time I felt comfortable coding on stage. The steps of my demos were well defined and rehearsed; I even had completed demos that I could use if I had a demo failure. I also felt comfortable changing the demos based on questions or comments of my audience. I need to keep the improvements I made and fix what didn’t work

Perspective

It is not my goal to oust Scott Hanselman as the Jon Skeet of technical speaking. I am using technical speaking (and Improv for that matter) to help me get outside of myself and the traditional dweeb mindset. I am getting out of my shell and doing thing I wouldn’t have done and going places I wouldn’t have gone 3 years ago.

EF Eager Loading Using Include()

Setup for this post

(if you want to run the code as displayed)

• Building an EF 4 Model Assembly for Pubs DB – To setup my Pubs model.
• Create Entity Framework Data Context for LINQPad 4 – To set up EF in LINQPad.
• Since I’m using C# Expression, I don’t need to declare EF_CONNECTION_STRING. I’m not sure why LINQPad can pick up the connection for C# Expression but not C# Program.

Lazy Loading is cool; you don’t have to load things you don’t need. However, each item you load is more expensive for each item you load; it can be a net saving if you can avoid loading enough unneeded data.

If you, the smart human, knew that you need to load that data, wouldn’t it be nice to tell the Entity Framework to go ahead and get the data NOW. I can tell EF to Eager Load specific related tables with the Include method. All I have to do is pass in the name of the navigator property of the related object you would like to load.

NOTE: LINQPad 4 is good at displaying the results of these queries in a way that may help you visualize what is happening. I spent a good amount of time trying to include that display: it was ugly.

For example, if I ran this query (LINQPad: C# Expression):

from s in stores.Include("sales")
    select s

This query would fetch all the stores and related sales.

If I wanted to load more than related object I could chain includes like this:

from s in stores.Include("sales").Include("discounts")
    select s

I get all the stores, related sales and discounts.

If I wanted to load related objects to related objects I would put a dot (".") between each level of related objects like this:

from d in discounts.Include("store.sales")
    select d

Here I get the discounts and the stores and the sales per store; the sales will appear below the stores.

Getting TSQL Query With ToTraceString() in EF

Setup for this post

(if you want to run the code as displayed)

• Building an EF 4 Model Assembly for Pubs DB – To setup my Pubs model.
• Create Entity Framework Data Context for LINQPad 4 – To set up EF in LINQPad.
• Querying EF ObjectContext from LINQPad – Why am I using EF_CONNECTION_STRING

I use ObjectQuery.ToTraceString() to figure out what is going on behind the scenes. ToTraceString() returns the TSQL (assuming you are using the SQL Server provider) for that ObjectQuery.

Since I can see the TSQL code that EF generates I can poke around and figure what is going around behind the curtain.

For example if you ran this in LINQPad:

void Main()
{
    PubsModel.pubsEntities context = new PubsModel.pubsEntities(EF_CONNECTION_STRING);

    // Entity SQL:
    // Returns ObjectQuery<T> directly
    ObjectQuery<author> esqlq = context.CreateQuery<author>(
        "SELECT VALUE a FROM authors AS a");
    esqlq.ToTraceString().Dump("--CreateQuery");
    
    // Linq to Entities
    // ObjectQuery<T> implements IQueryable<T>
    // This statement returns an ObjectQuery<T>
    // casted as IQueryable<T>
    IQueryable<author> linqq = from a in context.authors select a;    
    // So it must be cast back to execute ToTraceString()
    ((ObjectQuery)linqq).ToTraceString().Dump("--Linq Query");
}

You would get:

--CreateQuery

SELECT 
[Extent1].[au_id] AS [au_id], 
[Extent1].[au_lname] AS [au_lname], 
[Extent1].[au_fname] AS [au_fname], 
[Extent1].[phone] AS [phone], 
[Extent1].[address] AS [address], 
[Extent1].[city] AS [city], 
[Extent1].[state] AS [state], 
[Extent1].[zip] AS [zip], 
[Extent1].[contract] AS [contract]
FROM [dbo].[authors] AS [Extent1]  

--Linq Query

SELECT 
[Extent1].[au_id] AS [au_id], 
[Extent1].[au_lname] AS [au_lname], 
[Extent1].[au_fname] AS [au_fname], 
[Extent1].[phone] AS [phone], 
[Extent1].[address] AS [address], 
[Extent1].[city] AS [city], 
[Extent1].[state] AS [state], 
[Extent1].[zip] AS [zip], 
[Extent1].[contract] AS [contract]
FROM [dbo].[authors] AS [Extent1]  

Querying EF ObjectContext from LINQPad

I have noticed that if I create an ObjectContext or a decendant of ObjectContext (like pubsEntities from Building an EF 4 Model Assembly for Pubs DB), LINQPad can’t get the connection string correctly.

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <connectionStrings>
    <add name="pubsEntities" 
         connectionString="metadata=res://*/PubsModel.csdl|
         res://*/PubsModel.ssdl|res://*/PubsModel.msl;
         provider=System.Data.SqlClient;
         provider connection string='data source=.\SQLEXPRESS;
         attachdbfilename=&quot;C:\MDF\pubs.mdf&quot;;
         integrated security=True;connect timeout=30;
         user instance=True;multipleactiveresultsets=True;App=EntityFramework'" 
         providerName="System.Data.EntityClient" />
  </connectionStrings>
</configuration>

So I take the connection string from the app.config:

And copy it to a LINQPad C# Program .linq file as a constant on the top of the file (I am calling the constant EF_CONNECTION_STRING):

const string EF_CONNECTION_STRING = 
    @"metadata=res://*/PubsModel.csdl|res://*/PubsModel.ssdl|res://*/PubsModel.msl;" +
    @"provider=System.Data.SqlClient;" +
    @"provider connection string='data source=.\SQLEXPRESS;attachdbfilename=" + "\"" + 
    @"C:\MDF\pubs.mdf" + "\"" + 
    @";;integrated security=True;connect timeout=30;user instance=True;" +
    @"multipleactiveresultsets=True;App=EntityFramework'";

void Main()
{
    PubsModel.pubsEntities context = new PubsModel.pubsEntities(EF_CONNECTION_STRING);
    // Use Context Here
}