基于条件按降序排序

Question

我希望编写一个LINQ to Entity查询，该查询可以根据输入参数按升序或降序排序。有没有什么方法可以实现这个功能。 以下是我的代码，请提供建议。

    public List<Hosters_HostingProviderDetail> GetPendingApproval(SortOrder sortOrder)
    {
        List<Hosters_HostingProviderDetail> returnList = new List<Hosters_HostingProviderDetail>();
        int pendingStateId = Convert.ToInt32(State.Pending);
        //If the sort order is ascending
        if (sortOrder == SortOrder.ASC)
        {
            var hosters = from e in context.Hosters_HostingProviderDetail
                          where e.ActiveStatusID == pendingStateId
                          orderby e.HostingProviderName ascending
                          select e;
            returnList = hosters.ToList<Hosters_HostingProviderDetail>();
            return returnList;
        }
        else
        {
            var hosters = from e in context.Hosters_HostingProviderDetail
                          where e.StateID == pendingStateId
                          orderby e.HostingProviderName descending
                          select e;
            returnList = hosters.ToList<Hosters_HostingProviderDetail>();
            return returnList;
        }
    }

- Vinay Kumar Chella

Answer 1

我认为您无法将条件放入较大的查询中，但是您可以将其分成另一个C#语句，如下所示：

// Common code:
var hosters = from e in context.Hosters_HostingProviderDetail
              where e.ActiveStatusID == pendingStateId;

// The difference between ASC and DESC:
hosters = (sortOrder == SortOrder.ASC ? hosters.OrderBy(e => e.HostingProviderName) : hosters.OrderByDescending(e => e.HostingProviderName));

// More common code:
returnList = hosters.ToList<Hosters_HostingProviderDetail>();

- EMP

Answer 2

您可以通过以下步骤进一步减少它：

var hosters = from e in context.Hosters_HostingProviderDetail
              where e.ActiveStatusID == pendingStateId
              select e;

if (sortOrder == SortOrder.ASC)
   hosters = hosters.OrderBy(e => e.HostingProviderName);
else
    hosters = hosters.OrderByDescending(e => e.HostingProviderName);

return hosters.ToList<Hosters_HostingProviderDetail>();

- dnolan