Using IronRuby at Work: Part 1 – Using EF with IronRuby to retrieve data

• Part 1 – Using EF with IronRuby to retrieve data
• Part 2 – Using AssemblyBuilder and System.Reflection.Emit to create a .NET Assembly
• Part 3 – Creating the Domain class with CodeDom and IronRuby.

I will be giving a talk on this subject at this subject on November 6, 2010 at the Triangle .NET User Group’s RDU Code Camp

This is the first post in a three part series in which I will discuss how I used IronRuby to make my life easier.  In this post I’m going to discuss how IronRuby was used with Entity Framework 4 to retrieve data from a SQL Server database.

The Project – Use IronRuby to Produce a .NET Assembly

Our project consists of using 3 db tables to generate models and domain layer classes.  I chose to use IronRuby as the main language and to product an actual assembly that would contain the models and service classes. The goal of the project is to generate model and domain level code using 3 database tables.

The DB Tables

The three tables are elements, elements_to_views, and views.  The elements table holds all of the fields that will be needed to meet the requirements for this project.  The table’s main purposes is to satisfy a third-party requirement for documentation that means this table will always be up to date.  We will use this table as the main driver in the code generation process.  The views table is a way to group the elements into a set and we will use this to create the model classes.  Despite the name of this table these classes may or may not be used in the UI.  The elements_to_views table is used to relate the elements to their views which in the code means that the elements associated with a view will be a property in the view’s class. 

After setting up the EF entities I tried to interact with them directly from within the IronRuby script without success.  Since I’m new to IronRuby I’m not sure if it was something I was doing wrong or if it is a limitation, so instead of wasting a lot of time on figuring out I decided to create a Repository and ElementsService classes in C# to wrap the classes so I can get on with my IronRuby experimentation. (I’m not going to show the C# code here since I’m concentrating on IronRuby.  If you want to check out the code visit the the bitbucket project.)

Jumping into the IronRuby code…

Let me preface the rest of this post by saying I am a Ruby newb so please let me know if I”m breaking ruby coding practices or anything along those lines.  I’m learning it and loving it!  Any guidance would be appreciated.

After I finished the service class I was ready to start writing the IronRuby code.   My first class was a wrapper for the for the ElementsService C# class which I named….ElementsService.  Here is the code for the class:

What I’d like to discuss first are the two require lines at the top of the file.  The require ‘mscorlib’ brings in core Microsoft library.  The second is a reference to the assembly that contains the EF, Repository and ElementsService class.  The IRCDemo.Data assembly is in the same directory as the elements_service.rb file.Once those two requirements are loaded we have both assemblies at our disposal.  This means that any method that is available to you in C# is also available to you in IronRuby. 

Once we have the two assemblies loaded the script initializes the data context in the initialize method. The constructor in both Ruby and IronRuby classes.  The rest of the class just wraps calls to the C# version of the ElementsService class except for the get_properties method, which I will discuss in a later in the series.

Enough already, show me the data!

So now that we have the data access code in place lets write a script that gets all the data from the elements table.

Not much to this script but that’s the way I like it.  After loading the elements_service file the script instantiate an ElementsService object.  The next call is to the get_elements method which simply makes a call to the C# ElementsService.GetElements method.  When the results of the call are returned I loop through and print out the contents of the element record.  Once the data has been printed out the dispose method is called to ensure that the data context to ensure we clean up after ourselves.

To run the script above at the command prompt in the directory where the script exists enter:

ir blog.rb

will will produce output like this:

Summary

This is a good ending point for the first post in this series.  In this post we’ve laid out the foundation for the next two posts.  We’ve discussed how to interact with .NET assemblies from IronRuby.  In Part 2 we will take the .NET interoperability by using System.Reflection.Emit to create an assembly that contains the .NET model classes. 

You can download the code from here.

If You are Wondering Why I did this..

Why do this in IronRuby?  I’m in the process of teaching myself Ruby and Rails and the more I learn the more I like it.  So I’m looking for any excuse to introduce Ruby into our strictly MSFT environment.  Since this project is a proof of concept I thought it would be a nice starting point.

Addendum

I spent about five minutes attempting to get ActiveRecord to work with my SQL Server database without success that is why I went with the EF approach.  If anyone can point me to a resource that will help me get ActiveRecord up and running with SQL Server I’d appreciate it. Also, if there is anyone who has been successful in loading an EF generated model please let me know how you did  it.