Implementing Generic Repository using Entity framework code first

Question

I'm experiencing my first try on implementing Generic Repository Pattern and Unit of framework. I'm not using MVC on the project in hand. Please take a look at this method included in Generic Repository class:

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();
        }
    }

it must be a powerful method and accomplishes the goal of DRY well. My problem is that, I cannot order the result as descending? Can anyone write some lines of code to help me on this? Thanks,

score 2 · Answer 1 · answered May 17 '13 at 14:28

2

Have a look at this: http://prodinner.codeplex.com/ and this http://efmvc.codeplex.com/. These projects are good examples of simple architecture and you can see how generic repository is implemented and how it is used.

answered May 17 '13 at 14:28

eternity

1,668
15
25

Netricity · Accepted Answer · 2013-05-17T14:23:14.577

0

To filter by product category, try this:

var repo = new GenericRepository<Product>();

var results = repo.Get(
    p => p.Category.Name == "Foo");

Here we declare an instance of the Generic Repository, with an entity type of Product, then we pass a lamda expression that performs the filtering on each Product's Category whose name is "Foo".

edited May 17 '13 at 14:23

answered May 17 '13 at 14:17

Netricity

2,550
1
22
28

Well... Do you have any idea about where the filter operation is taken place? I precisely mean; the web server memory or the database? And also can you help how to order the result descending? Sorry, this is the first time working with this pattern and I know I need to study more about GENERICS in C# :( But I'd appreciate if could help me again.. – user2394196 May 17 '13 at 14:28
The filtering takes place in the database; EF converts your lambda expression to SQL and passes it to the database. Sorry, I don't know about the ordering, as I'm not familiar with that Func syntax. Perhaps someone else can help with that? – Netricity May 17 '13 at 14:44
PS, if you still need help with this, maybe don't mark the question as answered – Netricity May 17 '13 at 14:46
By this way some amount of memory are being saved and good deal. Ok my friend no problem for not answering the ordering.. Thanks again – user2394196 May 17 '13 at 14:48
oOopsSs.. Yes.. you're right.. But sorry I just cant hit the button of 'This answer is useful' I lack of some reputation and some stuff like that – user2394196 May 17 '13 at 14:51
Sorry bothering you with some comments but I finally figure it out and like to share it with you: return unitOfWork.CermonyCategoryRepository.Get(orderBy: cc => cc.OrderByDescending(s => s.CermCatID)).ToList(); – user2394196 May 17 '13 at 15:01
Glad you sussed it. Looks pretty simple once you know what you're doing. The intellisense makes it look complex. – Netricity May 17 '13 at 15:34

Implementing Generic Repository using Entity framework code first

2 Answers2

Linked