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Does Queryability and Lazy Loading in C# blur the lines of Data Access vs Business Logic?


I am experiencing a mid-career philosophical architectural crisis. I see the very clear lines between what is considered client code (UI, Web Services, MVC, MVP, etc) and the Service Layer. The lines from the Service layer back, though, are getting more blurred by the minute. And it all started with the ability to query code with Linq and the concept of Lazy loading.

I have created a Business Layer that consists of Contracts and Implementations. The Implementations then could have dependencies to other Contracts and so on. This is handled via an IoC Container with DI. There is one service that handles the DataAccess and all it does is return a UnitOfWork. This UnitOfWork creates a transaction when extantiated and commits the data on the Commit method. [View this Article (Testability and Entity Framework 4.0)]:

    public interface IUnitOfWork : IDisposable {
        IRepository<T> GetRepository<T>() where T : class;
        void Commit();
    }

The Repository is generic and works against two implementations (EF4 and an in-memory DataStore). T is made up of POCOs that get generated from the database schema or some EF4 object mapped from multiple DB objects. Testability is built into the Repository design. We can leverage the in-memory implementation to assert results with expectations since we are abstracting the data access query generator.

    public interface IRepository<T> where T : class {
        IQueryable<T> Table { get; }
        void Add(T entity);
        void Remove(T entity);
    }

While the data source is abstracted, IQueryable still gives me the ability to create queries anywhere I want within the business logic layer. Here is an example.

    public interface IFoo {
        Bar[] GetAll();
    }

    public class FooImpl : IFoo {
        IDataAccess _dataAccess;
        public FooImpl(IDataAccess dataAccess) {
            _dataAccess = dataAccess;
        }

        public Bar[] GetAll() {
            Bar[] output;
            using (var work = _dataAccess.DoWork()) {
                output = work.GetRepository<Bar>().Table.Where(b => b.IsActive == true).ToArray();
            }
            return output;
        }
    }

Now you can see how the queries could get even more complex as you perform joins with complex filters.

Therefore, my questions is:

  1. Is queryability considered data access or business logic when behind a repository layer that acts like an in-memory abstraction?

This article was originally a question posted on StackOverflow.

Red Gate’s SQL Source Control


I have been looking for a product like this for years and it is almost here. I am talking about an integrated source control IDE for SQL Server. Check out the following link and the details below:

SQL Source Control

Store your SQL Server databases under source control

  • Source control your database
  • Work directly in Management Studio, not with offline scripts
  • Connect your database to your existing source control system
  • Know who changed what, when, and why
  • Help the whole team stay in sync by easily getting the latest database version

There will be frequent early access releases as we develop SQL Source Control

  • The first early access release will support only Subversion
  • The next early access release will support Team Foundation Server
  • They’ll release version 1 in 2010
  • Sign up for the early access program and they’ll keep you updated

http://www.red-gate.com/products/SQL_Source_Control/index.htm

Dynamically loading javascript files


Below is a little piece of code that helped us facilitate dynamically loading javascript files.

// Please go here for details on the script below:
// http://unixpapa.com/js/dyna.html
var head = document.getElementsByTagName("head")[0];
var script = document.createElement('script');
script.setAttribute("id", id);
script.setAttribute("type", 'text/javascript');
script.setAttribute("src", url);
script.onload = function(){
   loadedCallback(sender, id);
};
script.onreadystatechange = function(){
   if (this.readyState == 'loaded' || this.readyState == 'complete') {
      loadedCallback(sender, id);
   }
};
head.appendChild(script);

As you can see the same callback loadedCallback(sender, id); is called twice. The first under the load function is only picked up by Firefox, Opera, etc. and the onreadystatechange is a Microsoft event. Took me forever to figure the Microsoft solution.

Recent Project List Cleaner


I have cleaned my Recent Project List in Visual Studio using a reg file before and even used a tool that integrates directly into visual studio. But, a new tool that I have found does the same as the latter but seems to have a tighter intergration with Visual Studio.

Please check out for Visual Studio 2005.

or for Visual Studio 2008

Happy .NETting