it is possible to implement FindBy method in Entity framework while we have this GenericRepository class :
public class Repository<T> : IRepository<T> where T : class, IAggregateRoot
{
private readonly DbSet<T> _entitySet;
public IQueryable<T> FindBy(Expression<Func<T, bool>> predicate)
{
//IQueryable<T> query=_entitySet.
}
}
how can I Implement FindBy in this case !??
My Repository has the following method to return a single entity by a given expression.
public T FindSingle(Expression<Func<T, bool>> predicate) {
return _entitySet.FirstOrDefault(predicate);
}
Now the caller can use any expression to get a single entity, like
var entity = _repository.FindSingle(entity=> entity.Id == 23);
or
var entity = _repository.FindSingle(entity=> entity.Name == "Hello World");
If your interface IAggregateRoot defines a property Id you can also add an an explicit method to your generic interface to get a single entity by its Id.
public interface IAggregateRoot {
int Id {get;}
}
public class GenericRepository {
public T FindSingleById(int id) {
return _entitySet.FirstOrDefault(entity=>entity.Id == id);
}
}
This should work
public class Repository<T> : IRepository<T> where T : class, IAggregateRoot
{
private readonly DbSet<T> _entitySet;
public IQueryable<T> FindBy(Expression<Func<T, bool>> predicate)
{
return _entitySet.Where(predicate).
}
}