internal static Dictionary <MethodInfo, Expression> Gather(Expression expression)
{
var gatherer = new OrderGatherer();
gatherer.Visit(expression);
return(gatherer.orderBys);
}
/// <summary>
/// 当客户端排序定义为空时，使用预定义的排序表达式。
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="source"></param>
/// <param name="orderPredicate"></param>
/// <returns></returns>
private static IQueryable <T> UseDefinitionQuery <T>(IQueryable <T> source, Expression <Func <IQueryable <T>, IQueryable <T> > > orderPredicate)
{
var sourceType = typeof(T);
var parExp = Expression.Parameter(sourceType, "s");
var orderBys = OrderGatherer.Gather(orderPredicate.Body);
var expression = source.Expression;
foreach (var kvp in orderBys)
{
expression = Expression.Call(null, kvp.Key, new[] { expression, kvp.Value });
}
return(source.Provider.CreateQuery <T>(expression));
}
