Implementing Generic Repository using Entity framework code first

问题

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,

回答1:

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".

回答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.

来源：https://stackoverflow.com/questions/16611031/implementing-generic-repository-using-entity-framework-code-first