Joining multiple tables in asp.net mvc5 using Entity Framework

Question

I'm trying to join two models and then select values from the joined table. What I've implemented is by far this from my understanding and gathering informations from different solutions in SO. But in x I'm always getting the values from first context context.EventSessionTeamModels but nothing from the second one. But everything from the Select block is needed to be fetched from the second one context.SessionModels. Maybe I've joined them in a wrong way. I need to know what needs to be done. Let me know if any other portion of the code is need other than the below code.

IQueryable<SessionShortModel>  shortInfoSession = context.EventSessionTeamModels
 .Join(context.SessionModels, x => x.session_id, y => y.session_id, (x, y) => x)
 .Where(x => x.event_id == eid && x.bp_id == attendeeId && x.role_code == "ATD")
 .Select(x => new SessionShortModel {
     StartTime = x.start_date,
     EndTime = x.end_date,
     Day = DbFunctions.TruncateTime(x.start_date),
     Year = x.start_date.Year,
     Month = x.start_date.Month,
     Name = x.session_name
    });

Anik Saha · Accepted Answer · 2016-01-19 21:44:14Z

1

May be it solve your issue. You get data from first table as you are using "x". Changing variable to "Y" you will get data from second table.

var data =(from ep in context.EventSessionTeamModels
             join e in context.SessionModels on ep.session_id equals e.session_id
             where ep.event_id == eid && ep.bp_id == attendeeId && ep.role_code == "ATD"
             select new SessionShortModel{
                 StartTime = e.start_date,
                 EndTime = e.end_date,
                 Day = DbFunctions.TruncateTime(e.start_date),
                 Year = e.start_date.Year,
                 Month = e.start_date.Month,
                 Name = e.session_name
             });

edited Jan 19, 2016 at 21:44

answered Jan 19, 2016 at 19:44

Anik Saha

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1 Comment

Gert Arnold Over a year ago

Maybe... care to explain why this would help?

J4ime · Accepted Answer · 2016-01-14 08:23:25Z

0

In EF you must to relationship the entities, EventSessionTeamModels needs has the propierty SessionModels

List<SessionShortModel>  shortInfoSession = context.EventSessionTeamModels
 .Include("SessionModels")
 .Where(x => x.SessionModels.event_id == eid && x.SessionModels.bp_id == attendeeId && x.SessionModels.role_code == "ATD")
 .Select(x => new SessionShortModel {
     StartTime = x.start_date,
     EndTime = x.end_date,
     Day = DbFunctions.TruncateTime(x.start_date),
     Year = x.start_date.Year,
     Month = x.start_date.Month,
     Name = x.session_name
    }).ToList();

answered Jan 14, 2016 at 8:23

J4ime

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2 Comments

Gert Arnold Over a year ago

I agree that navigation properties are more appropriate than joins, but the Include doesn't have any effect here, because the query ends with a projection.

J4ime Over a year ago

EventSessionTeamModels must has the propierty IEnumerabe<SessionModels> sessionsModels = get;set; and the relationship in the mapping info

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