This tutorial made use of the IDisposable interface for the UnitofWork class and an overrided dispose method in the controller.

However many other tutorials do not do this. May I ask why and if it is necessary to implement the IDisposable interface.

Thank you very much

forums.asp.net/

This StackOverflow thread also has some useful information:stackoverflow.com/

Unit of work interface:

using ContosoUniversity.Models;

namespace ContosoUniversity.DAL

{

public interface IUnitOfWork

{

void Save();

IStudentRepository StudentRepository { get; }

}

}

Unit of work implementing interface:

using ContosoUniversity.Models;

namespace ContosoUniversity.DAL

{

public class UnitOfWork : IUnitOfWork

{

private SchoolEntities context = new SchoolEntities();

private IStudentRepository studentRepository;

public IStudentRepository StudentRepository

{

get

{

if (this.studentRepository == null)

{

this.studentRepository = new StudentRepository(context);

}

return studentRepository;

}

}

public void Save()

{

context.SaveChanges();

}

}

}

Controller class variable and constructors - default constructor creating UofW and non-default allowing it to be passed in:

private IUnitOfWork unitOfWork;

public StudentController () : this (new UnitOfWork())

{

}

public StudentController (IUnitOfWork unitOfWork)

{

this.unitOfWork = unitOfWork;

}

You could do that but the way I would do it is make the mock unit of work class inject mock repositories the same way this unit of work class injects the EF repositories.

why does the get method:

public virtual IEnumerable<TEntity> Get(

Expression<Func<TEntity, bool>> filter = null,

Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBy = null,

string includeProperties = "")

{

IQueryable<TEntity> query = dbSet;

if (filter != null)

{

query = query.Where(filter);

}

foreach (var includeProperty in includeProperties.Split

(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries))

{

query = query.Include(includeProperty);

}

if (orderBy != null)

{

return orderBy(query).ToList();

}

else

{

return query.ToList();

}

}

accepts a Expression<Func<...>> for filter and "only" a Func<...> for orderBy Parameter? Wouldn't be a Func<...> for filter ok, too? (If yes, what would be the difference? Memory vs DB-execution?)

I understand that you can filter/order or better say "narrow down" the implementation with these parameters to get only the specific result you are looking for by the calling method. I am aware that Func<..> is basically just a delegate. However I have never really understood the difference to Expression<...>. Can somebody please clear this up on this example/method?

thanks!

For your second question, different people have different preferences for the best way to organize classes/layers into separate projects. StackOverflow is a great place to pose questions like that and get a lot of thoughtful answers from experienced developers.

I can't seem to figure out how to build the "query" filter outside of the lambda expression or predicate or whatever the "Get" method has in public virtual IEnumerable<TEntity> Get(

Expression<Func<TEntity, bool>> filter = null,

Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBy = null,

string includeProperties = "")

outside of doing it inline. I build a query based on user input for large search forms based on inputs for a results page. I built a GetNonQuery function for the Generic repo that will give me a count of records meeting the same criteria (expression) of the Get Query, but can't build the get query.

The GetAggregate function is as follows for those trying to build a search results page from this sample app.

public virtual object GetAggregate (

Expression<Func<TEntity, bool>> filter = null,

Func<IQueryable<TEntity>, object> aggregate = null)

{

IQueryable<TEntity> query = dbSet;

if (filter != null)

{

query = query.Where(filter);

}

if (aggregate != null)

{

return aggregate( query);

}

else

{

return null;

}

}

example of my query builing usage would be like dynamic link:

IQueryable<whatever> query = null;

if ( name != null)

query = query.Where( x=>x.name == name)

if ( age > 120)

query = query.Where( x=>x.age == "really old")

List<x> myList = query.ToList() (take, skip etc)

above GetAggregate function does the query.Count().

I'm sure I use unit of work by my new project.

Thanks

int pageIndex = (page ?? 1) - 1;

return View(students.ToPagedList(pageIndex, pageSize));

The value of pageIndex upon intial execution equals 0 and apparently the .ToPagedList( ) method will only allow 1 as the smallest value. Perhaps the .ToPagedList( ) method got changed internally at some point in time after this tutorial code was made?

Why do we need to dispose an object context? If SchoolContext is derived from DataContext, it should already implement the IDisposable interface?

Thanks