/// <summary>
/// Gets a paged list of users
/// </summary>
/// <param name="page">The page of users to get.</param>
/// <param name="pageSize">Size of the page.</param>
/// <param name="count">The number of users in the page.</param>
/// <returns></returns>
public IEnumerable <T> GetPagedUsers(int page, int pageSize, out long count)
{
// Optional parameters must appear after all other parameters
if (page < 1)
{
page = 1;
}
if (pageSize < 1)
{
pageSize = 25;
}
MongoCursor <T> accountsQuery = _db.Users().FindAllAs <T>();
// MongoCursor.Limit(x) restricts how many records can be retrieved
// But MongoCursor.Skip enumerates the list, removes the first N and returns the rest as an IEnumerable<T>
// This enumeration counts towards Limit. Once Skip is called, Limit is no longer useful.
// Therefore to our Limit we have to add the number of records that will be skipped.
accountsQuery.Limit = page * pageSize;
// Count() locks the cursor, so Limit can't be called anymore
count = accountsQuery.Count();
IEnumerable <T> accounts = accountsQuery.Skip((page - 1) * pageSize);
return(accounts);
}
/// <summary>
/// Paginate mongo cursor
/// </summary>
/// <param name="superset">MongoCursor</param>
/// <param name="pageNumber">Page Number</param>
/// <param name="pageSize">Page Size</param>
/// <exception cref="ArgumentOutOfRangeException"></exception>
public MongoPagedList(MongoCursor <T> superset, int pageNumber, int pageSize)
{
if (pageNumber < 1)
{
throw new ArgumentOutOfRangeException("pageNumber", pageNumber, "PageNumber cannot be below 1.");
}
if (pageSize < 1)
{
throw new ArgumentOutOfRangeException("pageSize", pageSize, "PageSize cannot be less than 1.");
}
// set source to blank list if superset is null to prevent exceptions
TotalItemCount = superset == null ? 0 : unchecked ((int)superset.Count());
PageSize = pageSize;
PageNumber = pageNumber;
PageCount = TotalItemCount > 0
? (int)Math.Ceiling(TotalItemCount / (double)PageSize)
: 0;
HasPreviousPage = PageNumber > 1;
HasNextPage = PageNumber < PageCount;
IsFirstPage = PageNumber == 1;
IsLastPage = PageNumber >= PageCount;
FirstItemOnPage = (PageNumber - 1) * PageSize + 1;
var numberOfLastItemOnPage = FirstItemOnPage + PageSize - 1;
LastItemOnPage = numberOfLastItemOnPage > TotalItemCount
? TotalItemCount
: numberOfLastItemOnPage;
// add items to internal list
if (superset != null && TotalItemCount > 0)
{
Subset.AddRange(pageNumber == 1
? superset.Skip(0).Take(pageSize).ToList()
: superset.Skip((pageNumber - 1) * pageSize).Take(pageSize).ToList()
);
}
}
/// <summary>
/// 对列表进行分页搜索
/// </summary>
/// <param name="bsonDocQuery"></param>
/// <returns></returns>
public List <BsonDocument> Search(int pageIndex, out int pageCount, MongoCursor <BsonDocument> bsonDocQuery)
{
if (bsonDocQuery == null)
{
pageCount = 0; return(null);
}
_totalPages = bsonDocQuery.Count();
pageCount = GetPageCount(_pageSize, _totalPages);
if (pageIndex == 0)
{
pageIndex = 1;
}
return(bsonDocQuery.Skip(_pageSize * ((int)pageIndex - 1)).Take(_pageSize).ToList());
}
/// <summary>
/// Splits a collection of objects into an unknown number of pages with n items per page (for example, if I have a list of 45 shoes and say 'shoes.Partition(10)' I will now have 4 pages of 10 shoes and 1 page of 5 shoes.
/// </summary>
/// <typeparam name="T">The type of object the collection should contain.</typeparam>
/// <param name="superset">The collection of objects to be divided into subsets.</param>
/// <param name="pageSize">The maximum number of items each page may contain.</param>
/// <returns>A subset of this collection of objects, split into pages of maximum size n.</returns>
public static IEnumerable <IEnumerable <T> > Partition <T>(this MongoCursor <T> superset, int pageSize)
{
if (superset.Count() < pageSize)
{
yield return(superset);
}
else
{
var numberOfPages = Math.Ceiling(superset.Count() / (double)pageSize);
for (var i = 0; i < numberOfPages; i++)
{
yield return(superset.Skip(pageSize * i).Take(pageSize));
}
}
}
