full entity framework repository interface

Question

I am looking for full ef repository interface (and implementation). I have this:

public interface IRepository<T> where T: class
{
    IQueryable<T> GetQuery();

    IEnumerable<T> GetAll();
    IEnumerable<T> Find(Func<T, bool> where);
    T Single(Func<T, bool> where);
    T First(Func<T, bool> where);

    void Delete(T entity);
    void Add(T entity);
    void Attach(T entity);
    void SaveChanges();
}

And I am looking an interface of all methods include SingleOrDefault and so on.
Where I can find such thing?

Answer 1

There are two ways to define repository. First is by exposing IQueryable which is enough to do anything:

public interface IRepository<T> where T: class
{
    IQueryable<T> GetQuery();

    // This method requires additional knowledge about entity
    // or more compilcated approach. The point of the method
    // is to check EF's internal storage first before querying DB 
    // T GetById(int Id);        

    void Delete(T entity);
    void Add(T entity);
    void Attach(T entity);
}

Having anything like GetAll or First is simply redundant because GetQuery servers it all. The second approach is specific repository where you don't expose IQueryable:

public interface IRepository<T> where T : class
{
    IEnumerable<T> GetAll();

    // Expressions!!!! Func will load all items to memeory
    // and then perform filtering by linq-to-objects!!!!!!
    IEnumerable<T> Find(Expression<Func<T, bool>> where);
    T Single(Expression<Func<T, bool>> where);
    T First(Expression<Func<T, bool>> where);

    void Delete(T entity);
    void Add(T entity);
    void Attach(T entity);
}

The second version is then derived by concrete repository interfaces which add methods like GetXXXOrderedByName, GetXXXWithRelatedYYY, etc.

Another point is that SaveChanges is usually not part of repository because you can need to modify items from multiple repositories and save changes on all of them by single method. For this purpose another pattern exists - unit of work.