我正在研究我的第一个 EntityFramework 解决方案，但我很困惑。
当我遍历生成的“日历”实体对象时，该属性calendar.ref_calendar_premisis.premisis未实例化（null）。我明白为什么，我停用了延迟加载，因为我想控制语法树投影中的条件“包含”，如下所示：
private List<CalendarBlockDTO> FillUserCalendar(DateTime start, DateTime end, int uid, bool everything)
{
var result = new List<CalendarBlockDTO>();
using (var db = new ViggoEntities())
{
//We need to disable lazyloading to use the "expression tree" syntax
db.Configuration.LazyLoadingEnabled = false;
//flip our "everything" so we can compare it to our "special" column
int specialScope = Convert.ToInt32(!everything);
//Build a query "Projection" with "expression tree" syntax
var query = from c in db.calendars
select new
{
calendarEntry = c,
createdByUser = c.MadeByUser,
premisesBookings = c.ref_calendar_premises.Where
(
rcp => rcp.deleted == 0 &&
(
//started before the start-parameter AND ended after start-parameter
(rcp.timestart < start && rcp.timeend > start) ||
//OR startet before the end-parameter AND ended after the end-parameter
(rcp.timestart < end && rcp.timeend > end) ||
//OR startet before the start-parameter AND ended after the end-paremeter
(rcp.timestart < start && rcp.timeend > end) ||
//OR startet after the start-parameter AND ended before the end-parameter
(rcp.timestart > start && rcp.timeend < end)
)
),
attendingGroups = c.ref_groups_calendar.Where
(
rug => rug.deleted == 0
),
groups = c.ref_groups_calendar.Select( rgc => rgc.usergroup ),
////Assignments not implemented yet
////assignments = c.
schedules = c.ref_calendar_schedule.Where
(
sch => sch.deleted == 0
)
};
var calEntries =
query.ToArray().Select(c => c.calendarEntry).
Where(
//If only special requested, show only special
c => c.special >= specialScope &&
//If not "MadeInInfo", show for creator as well
(c.madeininfo==0 && c.made_by == uid) ||
//Else, show to involved users
(c.ref_groups_calendar.Any(rgc => rgc.usergroup.ref_users_groups.Any(rug => rug.userid == uid)))
);
foreach (var calendar in calEntries)
{
//I WANT THIS TO NOT THROW AN EXCEPTION, PREMIS SHOULD NOT BE NULL
if (calendar.name == "Dinner with Allan" && calendar.ref_calendar_premises.Any(rcp => rcp.premis == null))
throw new Exception("Premis not instantiated!");
result.AddRange(CalendarToCalendarBlockDTOs(calendar));
}
}
return result;
}
我尝试添加类似：
...
room = c.ref_calendar_premises.Select(r => r.premis),
...
......但无济于事。在我们的测试数据中，已经为“与艾伦共进晚餐”活动预订了一个房间，但我似乎无法让它加载 premis-entyties。
我以前没有使用 EntityFramework、LINQ to SQL 或任何其他 ORM 的经验，所以我可能遗漏了一些显而易见的东西。
有什么建议么？