在实体查询的强类型LINQ中填充列表

Question

I am relatively new to LINQ and I'm simply trying to populate a List in a LINQ to Entities query. Any assistance would be greatly appreciated.

The class "SearchCriteria" looks like this:

public class SearchCriteria
{
   public IList<DTOEventType1> eventTypes { get; set; }
   public IList<DTOLocation1> locs { get; set; }
   [DataType(DataType.Date)]
   [DisplayFormat(ApplyFormatInEditMode = true,
      DataFormatString="0:dd/MM/yyyy}")]
   public DateTime? searchDate { get; set; }
   public List<PortfolioLibraryMVC4V2.Domain.DTO.DTOCalendarEvents> 
      CalendarEvents;
}

and my query is shown below:

var query = from E in medRepo.evt
    join L in medRepo.loc on E.LocationID equals L.LocationID
    join ET in medRepo.evtType on E.EventTypeID equals    
               ET.EventTypeID 
    where IDsOfSelectedEventTypes.Contains(E.EventTypeID) &&
          IDsOfSelectedLocations.Contains(L.LocationID) && 
          E.EventStart > eventslocs.searchDate 

    select new SearchCriteria
    {
        CalendarEvents = query.Select(x => new DTOCalendarEvents
        {
            Name = ET.Name,
            EventStart = E.EventStart,
            EventEnd = E.EventEnd
            }).ToList()
        };

        var datalist = query.ToList();

I'm trying to populate the list "CalendarEvents" in the Class SearchCriteria in the select in the above query. Currently, I get the error message "trying to use the local variable query before it is declared" so obviously my syntax isn't correct. Can someone show me the proper way to do this?

Thanks,

Pete

Answer 1

You can take SearchCriteria outside of the linq query..

var searchCriteria = new SearchCriteria();

searchCriteria.CalendarEvents = (from E in medRepo.evt
                                 join L in medRepo.loc 
                                 on E.LocationID equals L.LocationID
                                 join ET in medRepo.evtType 
                                 on E.EventTypeID equals ET.EventTypeID 
                                 where                     
                                 IDsOfSelectedEventTypes.Contains(E.EventTypeID) 
                                 && IDsOfSelectedLocations.Contains(L.LocationID) 
                                 && E.EventStart > eventslocs.searchDate)
                                .Select(x => new DTOCalendarEvents
                                {
                                 Name = ET.Name,
                                 EventStart = E.EventStart,
                                 EventEnd = E.EventEnd
                                })
                               .ToList();

basically we only need the list of events from the LINQ query.

Answer 2

Give this is a try:

var query = from E in medRepo.evt
    join L in medRepo.loc on E.LocationID equals L.LocationID
    join ET in medRepo.evtType on E.EventTypeID equals    
               ET.EventTypeID 
    where IDsOfSelectedEventTypes.Contains(E.EventTypeID) &&
          IDsOfSelectedLocations.Contains(L.LocationID) && 
          E.EventStart > eventslocs.searchDate 
    select new DTOCalendarEvents
    {
            Name = ET.Name,
            EventStart = E.EventStart,
            EventEnd = E.EventEnd
    };

    var datalist = query.ToList();

var searchCriteria = new SearchCriteria();
searchCriteria.CalendarOfEvents = datalist;