/// <summary>
/// 异步从 <see cref="IDbQueryable{TSource}"/> 创建分页记录 <see cref="PagedList{TSource}"/>
/// </summary>
/// <typeparam name="TSource">返回类型</typeparam>
/// <param name="source">查询序列</param>
/// <param name="pageIndex">当前页</param>
/// <param name="pageSize">页长，1024表示取所有记录</param>
/// <returns></returns>
public static async Task <PagedList <TSource> > ToPagedListAsync <TSource>(this IDbQueryable <TSource> source, int pageIndex, int pageSize = 10)
{
IList <TSource> result = null;
int rowCount = 0;
int pages = 0;
if (pageSize == 1024)
{
result = await source.ToListAsync();
rowCount = result.Count;
pageIndex = 1;
pages = 1;
}
else
{
if (pageSize == 0)
{
pageSize = 10;
}
rowCount = await source.CountAsync();
if (rowCount == 0)
{
result = new List <TSource>(0);
}
else
{
pages = rowCount / pageSize;
if (rowCount % pageSize > 0)
{
++pages;
}
if (pageIndex > pages)
{
pageIndex = pages;
}
if (pageIndex < 1)
{
pageIndex = 1;
}
result = await source.ToListAsync(pageIndex, pageSize);
}
}
return(new PagedList <TSource>(result, pageIndex, pageSize, rowCount));
}
/// <summary>
/// 异步从 <see cref="IDbQueryable<TElement>"/> 创建 <see cref="PagedList<TElement>"/>
/// pageSize = 1024 表示取所有
/// </summary>
public static async Task <PagedList <TElement> > ToPagedListAsync <TElement>(this IDbQueryable <TElement> source, int pageIndex, int pageSize = 10)
{
IList <TElement> result = null;
int totalCount = 0;
int totalPages = 0;
if (pageSize == 1024)
{
result = await source.ToListAsync();
totalCount = result.Count;
pageIndex = 1;
totalPages = 1;
}
else
{
if (pageSize == 0)
{
pageSize = 10;
}
totalCount = await source.CountAsync();
totalPages = totalCount / pageSize;
if (totalCount % pageSize > 0)
{
++totalPages;
}
if (pageIndex > totalPages)
{
pageIndex = totalPages;
}
if (pageIndex < 1)
{
pageIndex = 1;
}
result = await source.ToListAsync(pageIndex, pageSize);
}
return(new PagedList <TElement>(result, pageIndex, pageSize, totalCount));
}
/// <summary>
/// 返回序列中的元素数量
/// </summary>
public static async Task <int> CountAsync <TSource>(this IDbQueryable <TSource> source)
{
int num = await source.CountAsync(null);
return(num);
}