Question

我有一张桌子：

ForObjectTypeID (short, PK)
ForObjectID (int, PK)
UserID (int, PK)
Upvote (bool)
ShadowBannedVote (bool)

鉴于ObjectTypeID和ObjectID，我希望返回Tuple<int, int, int>，其中各自的值为：

总票数：ShadowBannedVote == false
Total Upvotes： Upvote == true && ShadowBannedVote == false
影子禁止投票总数：ShadowBannedVote == true

它需要是一个单独的编译查询，而不是分成多个查询。这是我已经得到的，我只是无法解决如何在返回值中执行总和和计数。

public static readonly Func<DBContext, ObjectType, int, Tuple<int, int, int>> GetTotalVotes = CompiledQuery.Compile(
    (DBContext db, ObjectType forObjectType, int forObjectID) =>
    db.UserVotes.Where(c => c.ForObjectTypeID == (short)forObjectType && c.ForObjectID == forObjectID)
    .Select(c=> new {c.Upvote, c.ShadowBannedVote}).Select(c=> new Tuple<int, int, in>(0, 0, 0)));

Answer 1

有兴趣看看这是否可行，但有一个解决方案是：

public static readonly Func<DBContext, ObjectType, int, IEnumerable<Tuple<bool, bool>>> GetTotalVotes = CompiledQuery.Compile(
    (DBContext db, ObjectType forObjectType, int forObjectID) =>
    db.UserVotes.Where(c => c.ForObjectTypeID == (short)forObjectType && c.ForObjectID == forObjectID)
    .Select(c=> new Tuple<bool, bool>(c.Upvote, c.ShadowBannedVote)));

然后简单地计算出应用程序逻辑中的数字。

Answer 2

您可以尝试按常量分组，求和并取结果，例如

  public static readonly Func<DBContext, ObjectType, int, Tuple<int, int, int>> GetTotalVotes = CompiledQuery.Compile(
        (DBContext db, ObjectType forObjectType, int forObjectID) 
   => 
   db.UserVotes
    .Where(c => c.ForObjectTypeID == (short)forObjectType 
             && c.ForObjectID == forObjectID)
    .Select(c => new { c.Upvote, c.ShadowBannedVote })
    .GroupBy(c => 1)
    .Select(c => new Tuple<int, int, int>(
        c.Count(r => !r.ShadowBannedVote), 
        c.Count(r => r.Upvote && !r.ShadowBannedVote), 
        c.Count(r => r.ShadowBannedVote)
    )).Single());

LINQ编译查询选择和多列

2 个答案: