public static FutureCount FutureCount <TEntity>(this IQueryable <TEntity> source, ObjectQuery <TEntity> sourceQuery)
where TEntity : class
{
if (source == null)
{
return(new FutureCount(0));
}
// create count expression
var expression = Expression.Call(
typeof(Queryable),
"Count",
new[] { source.ElementType },
source.Expression);
// create query from expression using internal ObjectQueryProvider
ObjectQuery countQuery = sourceQuery.CreateQuery(expression, typeof(int));
if (countQuery == null)
{
throw new ArgumentException("The source query must be of type ObjectQuery or DbQuery.", "source");
}
var futureContext = GetFutureContext(sourceQuery);
var future = new FutureCount(countQuery, futureContext.ExecuteFutureQueries);
futureContext.AddQuery(future);
return(future);
}
/// <summary>
/// 分页查询
/// </summary>
/// <typeparam name="TKey">排序类型</typeparam>
/// <param name="pageIndex">当前页</param>
/// <param name="pageSize">每页大小</param>
/// <param name="isAsc">是否升序排列，默认升序</param>
/// <param name="predicate">查询条件表达式</param>
/// <param name="keySelector">排序表达式</param>
/// <returns></returns>
public virtual IPage <T> Page <TKey>(int pageIndex, int pageSize, Expression <Func <T, bool> > predicate,
Expression <Func <T, TKey> > keySelector, bool isAsc = true)
{
if (pageIndex <= 0 && pageSize <= 0)
{
throw new Exception("pageIndex或pageSize不能小于等于0！");
}
IPage <T> page = new Page <T>()
{
PageIndex = pageIndex,
PageSize = pageSize
};
int skip = (pageIndex - 1) * pageSize;
if (predicate == null)
{
FutureCount fcount = this.dbset.FutureCount();
FutureQuery <T> futureQuery = isAsc
? this.dbset.AsNoTracking().OrderBy(keySelector).Skip(skip).Take(pageSize).Future()
: this.dbset.AsNoTracking().OrderByDescending(keySelector).Skip(skip).Take(pageSize).Future();
page.TotalItems = fcount.Value;
page.Items = futureQuery.ToList();
page.TotalPages = page.TotalItems / pageSize;
if ((page.TotalItems % pageSize) != 0)
{
page.TotalPages++;
}
}
else
{
var queryable = this.dbset.AsNoTracking().Where(predicate);
FutureCount fcount = queryable.FutureCount();
FutureQuery <T> futureQuery = isAsc
? queryable.OrderBy(keySelector).Skip(skip).Take(pageSize).Future()
: queryable.OrderByDescending(keySelector).Skip(skip).Take(pageSize).Future();
page.TotalItems = fcount.Value;
page.Items = futureQuery.ToList();
page.TotalPages = page.TotalItems / pageSize;
if ((page.TotalItems % pageSize) != 0)
{
page.TotalPages++;
}
}
return(page);
}
/// <summary>
/// Provides for defering the execution of the <paramref name="source" /> query to a batch of future queries.
/// </summary>
/// <typeparam name="TEntity">The type of the elements of <paramref name="source" />.</typeparam>
/// <param name="source">An <see cref="T:System.Linq.IQueryable`1" /> to add to the batch of future queries.</param>
/// <returns>An instance of <see cref="FutureCount"/> that contains the result of the query.</returns>
/// <seealso cref="T:EntityFramework.Future.FutureCount"/>
public static FutureCount FutureCount <TEntity>(this IQueryable <TEntity> source)
where TEntity : class
{
if (source == null)
{
return(new FutureCount(0));
}
ObjectQuery sourceQuery = source.ToObjectQuery();
if (sourceQuery == null)
{
// Early return for test scenarios, here so it only slows down the error path
if (source is IFutureTestQueryable)
{
return(new FutureCount(source, null));
}
throw new ArgumentException("The source query must be of type ObjectQuery or DbQuery.", "source");
}
// create count expression
var expression = Expression.Call(
typeof(Queryable),
"Count",
new[] { source.ElementType },
source.Expression);
// create query from expression using internal ObjectQueryProvider
ObjectQuery countQuery = sourceQuery.CreateQuery(expression, typeof(int));
var futureContext = GetFutureContext(sourceQuery);
var future = new FutureCount(countQuery, futureContext.ExecuteFutureQueries);
futureContext.AddQuery(future);
return(future);
}
