给定代码:
/// <summary>
/// Get a games high scores
/// </summary>
public static List<Score> GetGameHighScores(int gameID, HighScoreType type, int? skip = null, int? take = null)
{
var r = new List<Score>();
using (var db = new ArcadeContext())
{
var q = new List<ArcadeScore>();
if (skip != null && take != null)
{
switch (type)
{
case HighScoreType.ScoreRank:
q =
db.ArcadeScores.Where(c => c.GameID == gameID && c.ScoreRank > 0)
.OrderBy(c => c.ScoreRank)
.Skip(skip.Value)
.Take(take.Value)
.ToList();
break;
case HighScoreType.UserRank:
q =
db.ArcadeScores.Where(c => c.GameID == gameID && c.UserRank > 0)
.OrderBy(c => c.UserRank)
.Skip(skip.Value)
.Take(take.Value)
.ToList();
break;
}
}
else
{
switch (type)
{
case HighScoreType.ScoreRank:
q =
db.ArcadeScores.Where(c => c.GameID == gameID && c.ScoreRank > 0)
.OrderBy(c => c.ScoreRank)
.ToList();
break;
case HighScoreType.UserRank:
q =
db.ArcadeScores.Where(c => c.GameID == gameID && c.UserRank > 0)
.OrderBy(c => c.UserRank)
.ToList();
break;
}
}
r.AddRange(q.Select(arcadeScore => new Score(arcadeScore)));
}
return r;
}
skip
和 take
是可选参数(在需要分页时使用),获取正确记录的最佳方法是什么而不像上面那样重复自己?
最佳答案
与其在四个单独的查询之间切换,不如根据您的条件构建单个查询:
IQueryable<Score> query = db.ArcadeScores.Where(c => c.GameID == gameID);
switch(type)
{
case HighScoreType.ScoreRank:
query = query.Where(c => c.ScoreRank > 0).OrderBy(c => c.ScoreRank);
break;
case HighScoreType.UserRank:
query = query.Where(c => c.UserRank > 0).OrderBy(c => c.UserRank);
break;
}
if (skip.HasValue && take.HasValue)
query = query.Skip(skip.Value).Take(take.Value);
return query.ToList();
关于c# - 使用 Linq 查询 + 可选参数避免重复代码,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/17405348/