I would now like to expand
a little on what I stumbled through in part I of my Visual Studio 2010 post and touch on
a few other features of VS 2010. Specifically, I want to generate some code based off of an Entity Framework model and tie it up to an actual data source. Im not going to take the easy way and tie to
a SQL Server data source, though, I will tie it to an XML data file instead. Why? Well, why not? This is purely for learning, there are probably much better ways to get strongly-typed classes around XML but it will force us to go down
a path less travelled and maybe learn
a few things along the way. Once we get this XML data and the means to interact
with it, I will revisit data binding to this data in
a WPF form and see if I cant get reading, adding, deleting, and updating working smoothly
with minimal code. To begin, I will use what was learned in the first part of this blog topic and draw out
a data model for the MFL (My Football League) - I dont want the NFL to come down and sue me for using their name in this totally football-related article. The data model looks as follows,
with Teams having Players, and Players having
a position and statistics for each season they played: Note that when making the associations between these entities, I was given the option to create the foreign key but I only chose to select this option for the association between Player and Position. The reason for this is that I am picturing the XML that will contain this data to look somewhat like this: <MFL> <Position/> <Position/> <Position/> <Team> <Player> <Statistic/> </Player> </Team> </MFL> Statistic will be under its associated Player node, and Player will be under its associated Team node no need to have an Id to reference it if we know it will always fall under its parent. Position, however, is more of
a lookup value that will not have any hierarchical relationship to the player. In fact, the Position data itself may be in
a completely different xml file (something Id like to play around with), so in any case,
a player will need to reference the position by its Id. So now that we have
a simple data model laid out, I would like to generate two things based on it:
A class for each entity
with properties corresponding to each entity property An IO class
with methods to get data for each entity, either all instances, by Id or by parent. Now my experience
with code generation in the past has consisted of writing up little apps that use the code dom directly to regenerate code on demand (or using tools like CodeSmith). Surely, there has got to be
a more fun way to do this given that we are using the Entity Framework which already has built-in code generation for SQL Server support. Lets start
with that built-in stuff to give us
a base to work off of. Right click anywhere in the canvas of our model and select Add Code Generation Item: So just adding that code item seemed to do quite
a bit towards what I was intending: It apparently generated
a class for each entity, but also
a whole ton more. I mean
a TON more. Way too much complicated code was generated now that code is likely to be
a black box anyway so it shouldnt matter, but we need to understand how to make this work the way we want it to work, so lets get ready to do some stumbling through that text template (tt) file. When I open the .tt file that was generated, right off the bat I realize there is going to be trouble there is no color coding, no intellisense no nothing! That is going to make stumbling through more like groping blindly in the dark while handcuffed and hopping on one foot, which was one of the alternate titles I was considering for this blog. Thankfully, the community comes to my rescue and I wont have to cast my mind back to the glory days of coding in VI (look it up, kids). Using the Extension Manager (Available under the Tools menu), I did
a quick search for tt editor in the Online Gallery and quickly found the Tangible T4 Editor: Downloading and installing this was
a breeze, and after doing so I got some color coding and intellisense while editing the tt files. If you will be doing any customizing of tt files, I highly recommend installing this extension. Next, well see if that is enough help for us to tweak that tt file to do the kind of code generation that we wantDid you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take
a look: here.
