Linq to Sql Left join and get Average

Joined:	27/10/2007
Level:	Gold
Points:	314

Points:	5

Hi ,
Let's say i have an Linq query :

var query = from course in _unitOfWork.Course.GetAll()
join candidate in _unitOfWork.CandidateCourses.GetAll() on course.Id equals candidate.Course_id
join cr in _unitOfWork.CourseReviews.GetAll() on course.Id equals cr.Course_id into g from rt in g.DefaultIfEmpty()
where candidate.UserId == CandidateId
select new CourseFields
{
Id = course.Id,
Course_name = course.Course_name,
Course_description = course.Course_description,
Rating = g.Average(x => x.Rating),
TotalSections = sections.Count(),

};
return query;

Here i am getting exception in calculating Average of Rating, When there is no data in table for that particular course.

Can someone help where i am doing wrong..

Joined:	30/04/2012
Level:	Gold
Points:	7233

Points:	4

You can use this code snippet in Linq to Sql Left join and get Average

from s1 in gzClasses.e_userLongSessions                    
join s2 in gzClasses.e_userLongSessions
    on new {w = s1.workerId, n = s1.sessionNum} 
equals new {w = s2.workerId, n = s2.sessionNum - 1}
    into joined                    
from s2Null in joined.DefaultIfEmpty()                    
group new {s1, s2Null} by s1.workerId into g                    
orderby g.Key
select g.Average(e => (e.s2Null.startTime - e.s1.endTime).TotalSeconds);


Or 

Rating = g.DefaultIfEmpty(0).Average(x => x.Rating),

Linq to Sql Left join and get Average

About dotnetspider.com

Quick Links

General

Services