当我们使用单个用户调试下面的代码时它工作正常。但是当我们尝试运行负载测试时，当用户数超过30时我们就会得到 ＆＃34;转换为值类型＆＃39; System.Int32＆＃39;失败，因为具体化值为null。结果类型的通用参数或查询必须使用可空类型。＆＃34;异常。
这是我们获得例外的代码段。
profile.AccessRights = (
from t in entities.Opportunities
join x in entities.OpportunityWorkloadGroups on t.OpportunityId equals x.OpportunityId into oppworkloads
from ow in oppworkloads.DefaultIfEmpty()
join m in entities.OpportunityWorkloads on ow.OpportunityWorkloadGroupId equals m.OpportunityWorkloadGroupId into oppworkloadmodules
from om in oppworkloadmodules.DefaultIfEmpty()
join y in entities.OpportunityUsers on om.OpportunityWorkloadId equals y.OpportunityWorkloadId into users
from ou in users.DefaultIfEmpty()
where (((t.LookupOpportunityStatu.Name.Equals(Constants.EstimationStatusCompletedName) || t.LookupOpportunityStatu.Name.Equals(Constants.OpportunityStatusDiscardedName)
|| t.LookupOpportunityStatu.Name.Equals(OSEConstants.OpportunityStatusCompletedWithDiscards)) && !t.IsRestricted) ? true : ou.User.Alias == null ? true : ou.User.Alias == alias)
select new Microsoft.OneEstimator.DataAccess.Entities.AccessRights()
{
MasterUserId = userId,
MasterUserRole = roleName,
OpportunityId = t.OpportunityId,
IsOpportunityOwner = t.OpportunityOwner == userId ? true : false,
IsRestricted = t.IsRestricted,
StatusName = t.LookupOpportunityStatu.Name,
OpportunityWorkloadId = ow.OpportunityWorkloads.Any(m => m.OpportunityWorkloadGroupId == ow.OpportunityWorkloadGroupId) ? ow.OpportunityWorkloads.FirstOrDefault(m => m.OpportunityWorkloadGroupId == ow.OpportunityWorkloadGroupId).OpportunityWorkloadId : 0,
EstimationId = ow.OpportunityWorkloadGroupId == null ? 0 : ow.IsActive == false ? 0 : ow.OpportunityWorkloadGroupId,
RoleName = ou.Role == null ? string.Empty : ou.User.Alias == alias ? ou.Role.RoleName : string.Empty,
HasRightsForWA = ow.WorkloadGroupVersion != null ? entities.WorkloadGroupUsers.Any(y => y.WorkloadGroupId == ow.WorkloadGroupVersion.WorkloadGroup.WorkloadGroupId && y.UserId == userId && y.Role.RoleName.Equals(OSEConstants.Estimator)) : true,
WorkstreamUserRoleName = ow.WorkloadGroupVersion != null ? entities.WorkloadGroupUsers.FirstOrDefault(y => y.WorkloadGroupId == ow.WorkloadGroupVersion.WorkloadGroup.WorkloadGroupId && y.UserId == userId).Role.RoleName : string.Empty
}).ToList();
我想我对DefaultIfNull（）做错了不确定。