Get null for empty collection in LINQ Group - linq

Question

I am working on LINQ query and part of objective to do SQL database call once to achieve result. I have number of questions which may have collection of answers.
I need to choose all the questions and collection of answer and if there no answer for specific question, I still need it.
for code gives me only question which have answer but not ones without answer
var t3 = (Context.Answers
.Include(answer => answer.AnswerStatusType)
.Where(answer => Context.Questions.Where(q => q.profileId == ProfileId)
.Any(t => t.Id == answer.QuestionId)))
.GroupBy(
x => x.QuestionId,
x => x,
(key, g) => new
{
Question = key,
Answers = g.ToList(),
}
).ToList();

Answer 1

You probably need something like this:
var t3 =
(
from q in Context.Questions
where q.profileId == ProfileId
join a in Context.Answers on q.Id equals a.QuestionId into gas
select new
{
Question = q,
Answers = gas.ToList(),
}
).ToList();

Answer 2

I had the exact same problem and solved it with this giant query, which could probably be optimized, but maybe it will help someone with a similar problem.
// Perform left join to get all the questions (even those that don't have answers)
var results = (from quiz in db.Quizzes
join question in db.Questions on quiz.QuestionID equals question.QuestionID
from answer in db.QuestionAnswers.Where(a => question.QuestionID == a.QuestionID).DefaultIfEmpty()
where quiz.QuizID == quizId
group (answer != null ? new AnswerVM()
{
AnswerId = answer.AnswerID,
AnswerText = answer.AnswerText,
Correct = question.CorrectAnswerID != null ? answer.AnswerID == question.CorrectAnswerID : false,
} : null) // For the questions with no answers
by new
{
question.QuestionID,
question.DisplayOrder,
question.QuestionText,
question.CorrectAnswerID
} into g
select new QuestionVM
{
QuestionId = g.Key.QuestionID,
QuestionText = g.Key.QuestionText,
CorrectAnswerId = g.Key.CorrectAnswerID,
Answers = g.ToList()
})
.AsEnumerable()
.Select(x => {
// If there are no answers then group by will return the list with one value (null),
// then we need to change the answers list to be null (not the list with one null value)
if (x.Answers.Count(a => a != null) <= 0)
{
x.Answers = null;
}
return x;
}).ToList();