Group Concatenation with Linq - linq

Question

I have this:
var lstAssignmentDetails =
(from t1 in _unitOfWork.ReferralDetailsRepository.Get()
.Where(m => (m.ChartStatusID == (int)Utility.ReferralChartStatus.NotStaffed
|| m.ChartStatusID == (int)Utility.ReferralChartStatus.Partially_Staffed
|| m.ChartStatusID == (int)Utility.ReferralChartStatus.Restaff)
&& m.IsDeleted == false).OrderByDescending(x => x.ReferralDetailsId)
join t2 in _unitOfWork.ReferralRepository.Get() on t1.ReferralId equals t2.ReferralId
join t3 in _unitOfWork.PatientRepository.Get() on t2.PatientId equals t3.PatientId
join t4 in _unitOfWork.ClientRepository.Get() on t2.ClientId equals t4.ClientID
join t5 in _unitOfWork.DisciplineRepository.Get() on t1.DesciplineID equals t5.DesciplineID
join t6 in _unitOfWork.UserRepository.Get() on t2.CreatedBy equals t6.UserID
join t7 in _unitOfWork.PersonRepository.Get() on t6.PersonID equals t7.PersonID
join rt in _unitOfWork.ReferralTherapistRepository.Get() on t2.ReferralId equals rt.ReferralId
join t in _unitOfWork.TherapistRepository.Get() on rt.TherapistId equals t.TherapistId
join u in _unitOfWork.UserRepository.Get() on t.UserId equals u.UserID
join p in _unitOfWork.PersonRepository.Get() on u.PersonID equals p.PersonID
select new ReferralTempModel()
{
ReferralId = t1.ReferralId,
ClientName = t4.ClientName,
PatientName = t3.LastName + "," + t3.FirstName,
RefferalDate = t2.RefferalDate,
DisciplineID = t1.DisciplineID,
ReferralDetailsId = t1.ReferralDetailsId,
PatientId = t2.PatientId,
ClientID = t4.ClientID,
DiscName = t5.DesciplineType,
IsRejected = t1.IsRejected,
CreatedBy = t7.LastName + "," + t7.FirstName,
ChartstatusId = t1.ChartStatusID.Value
}).ToList();
return lstAssignmentDetails;
There are multiple ReferralTherapists for each referral. I need all the ReferralTherapists for each referral to be concatenated into one field. Essentially what I want to do is a GROUP_CONCAT using LINQ.
I know this is probably a duplicate, but none of the previous questions handles anything as complicated as this. Trying to add GroupBy always seems to create an error no matter where I place it.

Answer 1

Start by not joining other referrals as t2 when constructing your flat list, and adding therapist's name to the anonymous type:
var flatListAssignmentDetails =
(from t1 in _unitOfWork.ReferralDetailsRepository.Get()
.Where(m => (m.ChartStatusID == (int)Utility.ReferralChartStatus.NotStaffed
|| m.ChartStatusID == (int)Utility.ReferralChartStatus.Partially_Staffed
|| m.ChartStatusID == (int)Utility.ReferralChartStatus.Restaff)
&& !m.IsDeleted)
join t2 in _unitOfWork.ReferralRepository.Get() on t1.ReferralId equals t2.ReferralId
join t3 in _unitOfWork.PatientRepository.Get() on t2.PatientId equals t3.PatientId
join t4 in _unitOfWork.ClientRepository.Get() on t2.ClientId equals t4.ClientID
join t5 in _unitOfWork.DisciplineRepository.Get() on t1.DesciplineID equals t5.DesciplineID
join t6 in _unitOfWork.UserRepository.Get() on t2.CreatedBy equals t6.UserID
join t7 in _unitOfWork.PersonRepository.Get() on t6.PersonID equals t7.PersonID
select new {
t1.ReferralId,
t4.ClientName,
PatientName = t3.LastName + "," + t3.FirstName,
t2.RefferalDate,
t1.DisciplineID,
t1.ReferralDetailsId,
t2.PatientId,
t4.ClientID,
DiscName = t5.DesciplineType,
t1.IsRejected,
CreatedBy = t7.LastName + "," + t7.FirstName,
ChartstatusId = t1.ChartStatusID.Value,
TherapistName = p.LastName + "," + p.FirstName
}).ToList();
Now you can group your list, and concatenate therapist names:
var listAssignmentDetails = flatListAssignmentDetails
.GroupBy(r => r.ReferralId)
.Select(g => new ReferralTempModel {
ReferralId = g.First().ReferralId,
ClientName = g.First().ClientName,
PatientName = g.First().PatientName,
RefferalDate = g.First().RefferalDate,
DisciplineID = g.First().DisciplineID,
ReferralDetailsId = g.First().ReferralDetailsId,
PatientId = g.First().PatientId,
ClientID = g.First().ClientID,
DiscName = g.First().DiscName,
IsRejected = g.First()..IsRejected,
CreatedBy = g.First().CreatedBy,
ChartstatusId = g.First().ChartStatusID,
TherapistNames = string.Join(", ", g.Select(r => r.TherapistName))
}).ToList();
One thing to note here is that all fields that are tied to all referrals in the group are obtained through g.First() construct. The field with "group concatenation" is produced using string.Join method on a projection of TherapistName from the group.