Linq to SQL 一次格式化日期时间

Question

在 Whosebug 上多次询问如何在 linq 中格式化日期时间到 sql 表达式，解决方案总是首先使用 ToList() 强制编译 linq，然后处理使用 .ToString("hh:mm") 格式化选项的奢侈日期时间。

但是我试图一次性完成并且我部分成功了，除了代码既糟糕又丑陋，任何更短的方法来做到这一点，假设日期对象是一个 unix 时间戳存储在db，我正在尝试 return 只是时间部分 4:54 pm。

            production_cycles = from p in db.ProductionCycles
                                where p.IsRunning == true
                                select new Rest.ProductionCycle {
                                    id = p.ID,
                                    name = p.Name,
                                    created = p.Created,
                                    steps = from s in p.Logs
                                            where user_permissions.Contains(s.Permission.ID)
                                            orderby s.ID ascending
                                            select new Rest.Step {
                                                created = s.Created,
                                                created_label = DbFunctions.CreateDateTime(
                           (int)SqlFunctions.DatePart("yyyy", (DateTime)SqlFunctions.DateAdd("ss", s.Created + (offset * 60 * 60), new DateTime(1970, 1, 1, 0, 0, 0, 0))),
                           (int)SqlFunctions.DatePart("m", (DateTime)SqlFunctions.DateAdd("ss", s.Created + (offset * 60 * 60), new DateTime(1970, 1, 1, 0, 0, 0, 0))),
                           (int)SqlFunctions.DatePart("d", (DateTime)SqlFunctions.DateAdd("ss", s.Created + (offset * 60 * 60), new DateTime(1970, 1, 1, 0, 0, 0, 0))),
                           (int)SqlFunctions.DatePart("hh", (DateTime)SqlFunctions.DateAdd("ss", s.Created + (offset * 60 * 60), new DateTime(1970, 1, 1, 0, 0, 0, 0))),
                           (int)SqlFunctions.DatePart("mi", (DateTime)SqlFunctions.DateAdd("ss", s.Created + (offset * 60 * 60), new DateTime(1970, 1, 1, 0, 0, 0, 0))),
                           0

                          ).Value.Hour.ToString() 
                          + ":" +
                            DbFunctions.CreateDateTime(
                           (int)SqlFunctions.DatePart("yyyy", (DateTime)SqlFunctions.DateAdd("ss", s.Created + (offset * 60 * 60), new DateTime(1970, 1, 1, 0, 0, 0, 0))),
                           (int)SqlFunctions.DatePart("m", (DateTime)SqlFunctions.DateAdd("ss", s.Created + (offset * 60 * 60), new DateTime(1970, 1, 1, 0, 0, 0, 0))),
                           (int)SqlFunctions.DatePart("d", (DateTime)SqlFunctions.DateAdd("ss", s.Created + (offset * 60 * 60), new DateTime(1970, 1, 1, 0, 0, 0, 0))),
                           (int)SqlFunctions.DatePart("hh", (DateTime)SqlFunctions.DateAdd("ss", s.Created + (offset * 60 * 60), new DateTime(1970, 1, 1, 0, 0, 0, 0))),
                           (int)SqlFunctions.DatePart("mi", (DateTime)SqlFunctions.DateAdd("ss", s.Created + (offset * 60 * 60), new DateTime(1970, 1, 1, 0, 0, 0, 0))),
                           0

                          ).Value.Minute.ToString()                         


                          ,
                                                username = s.User.Name,

Answer 1

请试试这个：

var baseDate = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
production_cycles = from p in db.ProductionCycles
    where p.IsRunning == true
    select new Rest.ProductionCycle
    {
        id = p.ID,
        name = p.Name,
        created = p.Created,
        steps = from s in p.Logs
            where user_permissions.Contains(s.Permission.ID)
            orderby s.ID ascending
            select new Rest.Step
            {
                created = s.Created,
                created_label = DbFunctions.DiffHours(baseDate, s.Created).ToString + ":" + DbFunctions.DiffMinutes(baseDate, s.Created).ToString + ":" +DbFunctions.DiffSeconds(baseDate, s.Created).ToString

                ////// the rest as usual

            },
    };

Linq to SQL 一次格式化日期时间

Linq to SQL Format Date time in One Take

c#

linq

linq-to-sql