/// <summary>
/// Returns a single page of results from an IOrderedQueryable.
/// </summary>
/// <typeparam name="T">The collection type.</typeparam>
/// <param name="source">The collection to be paged.</param>
/// <param name="request">An IPageRequest specifying a PageSize and a PageNumber to reduce the collection by.</param>
/// <returns>the IOrderedQueryable with Skip() and Take() applied.</returns>
public static IQueryable <T> Page <T>(this IOrderedQueryable <T> source, IPageRequest request)
{
if (request != null)
{
return(source.Page(request.PageNumber, request.PageSize));
}
return(source);
}
/// <summary>
/// Расширение для постраничного вывода коллекции
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="obj">Коллекция</param>
/// <param name="page">Номер страницы</param>
/// <param name="pageSize">Количество элементов на странице</param>
/// <param name="objectsCount">Общее количество объектов в коллекции</param>
/// <returns></returns>
public static IQueryable <T> Page <T>(this IOrderedQueryable <T> obj, int page, int pageSize, out int objectsCount)
{
objectsCount = obj.Count();
if (page > 1 && (page - 1) * pageSize >= objectsCount)
{
page = (objectsCount - 1) / pageSize + 1;
}
return(obj.Page(page, pageSize));
}
public static Page <T> ToPage <T>(this IOrderedQueryable <T> source, Query r)
{
return(new Page <T>
{
PageSize = r.PageSize,
Count = source.Count(),
List = source.Page(r).ToList(),
PageIndex = r.Page
});
}
public static async Task <AiurPagedCollection <T> > BuildAsync <T>(
IOrderedQueryable <T> query,
IPageable pager,
ErrorType code,
string message)
{
var items = await query.Page(pager).ToListAsync();
return(new AiurPagedCollection <T>(items)
{
TotalCount = await query.CountAsync(),
CurrentPage = pager.PageNumber,
CurrentPageSize = pager.PageSize,
Code = code,
Message = message
});
}
public void Entities_Page()
{
//Arrange
const int total = 33;
const int page = 2;
const int pageSize = 10;
PopulateTestData(total, 0);
//Act
var expected = _context.Blogs.OrderBy(b => b.BlogId).Page(page, pageSize).ToArray();
IOrderedQueryable queryable = _context.Blogs.Select("it").OrderBy("BlogId");
bool any = queryable.Any();
var count = queryable.Count();
var result = queryable.Page(page, pageSize).ToDynamicArray <Blog>();
//Assert
Assert.Equal(true, any);
Assert.Equal(total, count);
Assert.Equal(expected, result);
}
/// <summary>
/// Esegue l'operazione per tutte le entità nella in entities, salvando ad ogni pagina
/// </summary>
/// <remarks>http://stackoverflow.com/questions/5940225/fastest-way-of-inserting-in-entity-framework/5942176#5942176</remarks>
/// <typeparam name="TEntity"></typeparam>
/// <param name="context"></param>
/// <param name="entities"></param>
/// <param name="action"></param>
public static void BulkOperation <TEntity>(this DbContext context, IOrderedQueryable <TEntity> entities, Action <TEntity> action, int pagingCount = 100)
{
using (var scope = new TransactionScope(TransactionScopeOption.Required, TimeSpan.FromMinutes(15)))
{
var entitiesCount = entities.Count();
var pagesCount = (int)Math.Ceiling((decimal)entitiesCount / (decimal)pagingCount);
for (int i = pagesCount - 1; i >= 0; i--)
{
var pagedEntities = entities.Page(i, pagingCount).ToList();
foreach (var entity in pagedEntities)
{
action(entity);
}
context.SaveChanges();
// clear the entities tracking
context.ChangeTracker.Entries().ToList().ForEach(e => e.State = EntityState.Detached);
}
scope.Complete();
}
}
