public static void Configure <T>(this ISupportPaging grid,
IQueryable <T> query,
Func <int> totalRowCount,
int pageSize = 100)
{
ValidateInput(grid, query, totalRowCount, pageSize);
grid.PageSize = pageSize;
grid.OnGotoFirst = () => grid.SetDataSource(First, query);
grid.OnGotoPrev = () => grid.SetDataSource(Prev, query);
grid.OnGotoNext = () => grid.SetDataSource(Next, query);
grid.OnGotoLast = () => grid.SetDataSource(Last, query);
if (grid.TotalPages == null)
{
//local copy to avoid possible multiple enumerations.
var total = totalRowCount();
//
grid.TotalPages = () => CalculatePages(grid, total);
}
//Goes to the first page.
grid.SetDataSource(First, query);
grid.CleanUp = () =>
PagingCache.Remove(grid);//<= to avoid memory leaks.
if (grid.EndConfigure != null)
{
grid.EndConfigure();
}
grid.Configured = true;
}
static IEnumerable <T> Prev <T>(this ISupportPaging grid, IQueryable <T> dataSource)
{
if (grid.CurrentPage != 0)
{
grid.CurrentPage--;
}
return(grid.GetPage(dataSource));
}
static IEnumerable <T> Last <T>(this ISupportPaging grid, IQueryable <T> dataSource)
{
if (grid.TotalPages() > 0)
{
grid.CurrentPage = grid.TotalPages() - 1;
}
return(grid.GetPage(dataSource));
}
static IEnumerable <T> Next <T>(this ISupportPaging grid, IQueryable <T> dataSource)
{
if (grid.CurrentPage < grid.TotalPages() - 1)
{
grid.CurrentPage++;
}
return(grid.GetPage(dataSource));
}
internal static void Remove(ISupportPaging grid)
{
var key = new CacheKey(grid);
if (_storage.ContainsKey(key))
{
_storage.Remove(key);
}
}
static void SetDataSource <T>(this ISupportPaging grid, Func <ISupportPaging, IQueryable <T>, IEnumerable <T> > gotoPage, IQueryable <T> source)
{
grid.DataSource = null;
grid.DataSource = QueryToSortableDataSource(gotoPage(grid, source));
if (grid.OnPageChange != null)
{
grid.OnPageChange();
}
}
private static int CalculatePages(ISupportPaging grid, int total)
{
var result = total / grid.PageSize;
if (total % grid.PageSize != 0)
{
result++;
}
return(result);
}
private static IEnumerable <T> GetCached <T>(ISupportPaging grid)
{
var key = new CacheKey(grid);
if (!_storage.ContainsKey(key))
{
return(null);
}
return((IEnumerable <T>)_storage[key]);
}
private static void Cache <T>(ISupportPaging grid, IEnumerable <T> queryResult)
{
var key = new CacheKey(grid);
if (_storage.ContainsKey(key))
{
_storage.Remove(key);
}
_storage.Add(key, queryResult);
}
public static void Search <T>(this ISupportPaging grid,
IQueryable <T> source,
Func <T, bool> criteria)
{
if (!grid.Configured)
{
throw new InvalidOperationException(
"You have to configure the grid first. Take a look at the configure method");
}
PagingCache.Invalidate();
grid.SetDataSource(First, source.Where(criteria).AsQueryable());
}
public static PageInfo?BuildPage(this ISupportPaging pagingProvider, int?totalRowCount = null)
{
if (pagingProvider.Pagination == null)
{
return(null);
}
var pagination = pagingProvider.Pagination;
return(new PageInfo(pagination.PageIndex, totalRowCount)
{
PageSize = pagination.PageSize
});
}
public static IEnumerable <T> CacheAndReturn <T>(ISupportPaging grid,
IQueryable <T> dataSource)
{
var result = GetCached <T>(grid);
if (result == null)
{
Cache(grid,
//paging in action
(from p in dataSource select p)
.Skip(/*start page*/ grid.CurrentPage * grid.PageSize)
.Take(grid.PageSize)
.ToList()); //only at this point we hit the database
}
//***********************************************************
return(GetCached <T>(grid));
}
private static void ValidateInput <T>(ISupportPaging grid, IQueryable <T> query, Func <int> totalRowCount, int pageSize)
{
if (grid == null)
{
throw new ArgumentNullException("grid");
}
if (query == null)
{
throw new ArgumentNullException("query");
}
if (totalRowCount == null)
{
throw new ArgumentNullException("totalRowCount");
}
if (pageSize < 1)
{
throw new ArgumentException("Page size must be greater than zero.");
}
}
public static IQueryable <T> ApplyPaging <T>(this ISupportPaging pagingProvider, IQueryable <T> query)
{
if (pagingProvider.Pagination == null)
{
return(query);
}
var pagination = pagingProvider.Pagination;
if (pagination.PageSize.HasValue &&
pagination.PageIndex.HasValue)
{
var skip = (pagination.PageIndex.Value - 1) * pagination.PageSize.Value;
var take = pagination.PageSize.Value;
query = query
.Skip(skip)
.Take(take);
}
return(query);
}
static IEnumerable <T> GetPage <T>(this ISupportPaging grid,
IQueryable <T> dataSource)
{
return(PagingCache.CacheAndReturn(grid, dataSource));
}
//
private static IEnumerable <T> InternalSearch <T>(this ISupportPaging grid, IQueryable <T> dataSource)
{
grid.CurrentPage = 0;
PagingCache.Invalidate();//maybe this is not the best way to go....
return(grid.GetPage(dataSource));
}
public CacheKey(ISupportPaging grid)
{
_grid = grid;
_gridPage = grid.CurrentPage;
}
//paging strategies.
static IEnumerable <T> First <T>(this ISupportPaging grid,
IQueryable <T> dataSource)
{
grid.CurrentPage = 0;
return(grid.GetPage(dataSource));
}
