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Mapping problem, object reference not set to an instance

I got a small problem here. I got a course class and a User. I want to show all the Users inside a Course through the API.
the error i get,
'Object reference not set to an instance of an object.'
And this is my controller method,
var objList = _courseRepo.GetUsers(CourseId);
if (objList == null)
{
return NotFound();
}
var objToShow = new List<ViewCourseDetailsDTO>();
foreach (var obj in objList)
{
objToShow.Add(_mapper.Map<ViewCourseDetailsDTO>(obj));
}
return Ok(objToShow);
The Error i got is inside the Foreach-loop. It says that i need to create an object...
This is how my DTO classes looks like,
public class ViewCourseDetailsDTO
{
public int CourseId { get; set; }
public string CourseTitle { get; set; };
public ICollection<UserDTO>? Users { get; set; } = new List<UserDTO>();
}
And this one,
public class UserDTO
{
public string ID { get; set; }
public string UserName { get; set; }
public string Name { get; set; }
}
Do you think i have to break out the UserDTO somehow? Is it Therefore u think ?
if you want to see my CourseRepository than its here,
public ICollection<Course> GetUsers(int courseId)
{
return _db.Course.Where(c => c.CourseId == courseId).Include(a => a.Users).ToList();
}
Would be really grateful if you could help me out here.

Wohooo I found it, damnit!
On my controller, i forgot to put in mapper here,
public CourseController(ICourseRepository courseRepo, IMapper mapper)
{
_courseRepo = courseRepo;
_mapper = mapper;
}
I had injected it correct at the top but forgot to put it inside there ^

New class selected by LINQ query, how to transfer to another model?

I'm really not understanding this as I've only dabbled in MVC and C#. I apologize if my terminology is wrong or confusing, I will do my best to answer questions. I have a couple models like so:
public class DataSharingModels
{
public string ReferenceID { get; set; }
public NBTC NBTCGroup { get; set; }
public Contractors ContractorsGroup { get; set; }
public Coordinators CoordinatorsGroup { get; set; }
public NGO NGOGroup { get; set; }
public Public PublicGroup { get; set; }
public SelectList FA_RA_List { get; set; }
}
public class NBTC
{
public String NBTC_FA_Centroid { get; set; }
public String NBTC_FA_Bound { get; set; }
public String NBTC_RA_Centroid { get; set; }
//more properties...
}
The DataSharingModels class contains the public NBTC NBTCGroup property. It is not public List<NBTC> NBTCGroup because there will only be one produced per instance of the controller being hit.
Now in my controller, I have a LINQ statement that selects a new NBTC class:
var nbtcVals = (from ds in db.SharingPermissions
where ds.FocalRefID.ToString() == ReferenceID
&& ds.ShareGroup == "NBTC"
select new NBTC
{
NBTC_FA_Centroid = ds.CIP_FA_Centroid,
NBTC_FA_Bound = ds.CIP_FA_Boundary,
NBTC_RA_Centroid = ds.CIP_RA_Centroid,
//more properties...
});
Where I'm going wrong is I would like to add that to my DataSharingModels model. I thought the nbtcVals type would be NBTC, but it's IQueryable<##.Models.NBTC>. I understand I could do this, but it seems redundant:
DataSharingModels dsm = new DataSharingModels();
if (nbtcVals.Any())
{
foreach (var i in nbtcVals)
{
dsm.NBTCGroup.NBTC_FA_Centroid = i.NBTC_FA_Centroid;
dsm.NBTCGroup.NBTC_FA_Boundary = i.NBTC_FA_Bound;
dsm.NBTCGroup.NBTC_RA_Centroid = i.NBTC_RA_Centroid;
//more properties...
}
}
What is a more direct way to do this? There must be one. I supposed I could also return an anonymous type in the LINQ query and then assign each property in the foreach like dsm.NBTCGroup.NBTC_RA_Centroid = i.NBTC_RA_Centroid but that seems the same as the other way.

var nbtcgroup = (from ds in db.SharingPermissions
where ds.FocalRefID.ToString() == ReferenceID
&& ds.ShareGroup == "NBTC"
select new NBTC
{
NBTC_FA_Centroid = ds.CIP_FA_Centroid,
NBTC_FA_Bound = ds.CIP_FA_Boundary,
NBTC_RA_Centroid = ds.CIP_RA_Centroid,
//more properties...
})
.OrderByDescending(n => n.Id) // or some other property that could identify sorting
.FirstOrDefault();
This one has a translation to SQL (LIMIT or TOP depending on backend).

Data from model not passing to view

I have some code that is functioning oddly and was wondering if anyone else hase come across this issue.
I have a view model that collects data from a database via a stored procedure and a vb object (no I do not know vb this is legacy)
When I execute the program the data is collected as expected via the controller. When I debug it I can see all of my parameters populating with information. However when it comes to the view it says that the parameters are null. I have included my code
Models:
public class PersonIncomeViewModel
{
public string IncomeTypeDesc { get; set; }
public string IncomeDesc { get; set; }
public string Income { get; set; }
}
public class PersonIncomeListViewModel
{
public int? PersonId { get; set; }
public List<PersonIncomeListItem> Incomes { get; set; }
public PersonIncomeListViewModel()
{
Incomes = new List<PersonIncomeListItem>();
}
}
public class PersonLookupViewModel : Queue.QueueViewModel
{
public int Action { get; set; }
public bool ShowAdvancedFilters { get; set; }
//Person Search Variables
[Display(Name = #"Search")]
public string SpecialSearch { get; set; }
[Display(Name = #"Person Id")]
public int? PersonId { get; set; }
[Display(Name = #"Full Name")]
public string FullName { get; set; }
[Display(Name = #"SSN")]
public string SSN { get; set; }
public string AddressStatus { get; set; }
public string EmploymentStatus { get; set; }
public PersonIncomeViewModel Income { get; set; }
public List<PersonIncomeListItem> Incomes { get; set; }
public PersonLookupViewModel()
{
Income = new PersonIncomeViewModel();
Incomes = new List<PersonIncomeListItem>();
}
}
Controller:
public ActionResult _Income(int id)
{
var vm = new PersonLookupViewModel();
var personManager = new dtPerson_v10_r1.Manager( ref mobjSecurity);
//var person = personManager.GetPersonObject((int)id, vIncludeIncomes: true);
var person = personManager.GetPersonObject(id, vIncludeIncomes: true);
var look = JsonConvert.SerializeObject(person.Incomes);
foreach (dtPerson_v10_r1.Income income in person.Incomes)
{
if (income.IncomeType_ID == 0)
{
var item = new PersonIncomeListItem
{
IncomeTypeDesc = "Unknown",
IncomeDesc = income.IncomeDesc,
Income = mobjFormat.FormatObjectToCurrencyString(income.Income)
};
vm.Incomes.Add(item);
}
if (income.IncomeType_ID == 1)
{
var item = new PersonIncomeListItem
{
IncomeTypeDesc = "Alimony",
IncomeDesc = income.IncomeDesc,
Income = mobjFormat.FormatObjectToCurrencyString(income.Income)
};
vm.Incomes.Add(item);
}
if (income.IncomeType_ID == 2)
{
var item = new PersonIncomeListItem
{
IncomeTypeDesc = "Child Support",
IncomeDesc = income.IncomeDesc,
Income = mobjFormat.FormatObjectToCurrencyString(income.Income)
};
vm.Incomes.Add(item);
}
}
return PartialView(vm);
}
View:
#using dtDataTools_v10_r1
#using ds_iDMS.Models.Person
#model ds_iDMS.Models.Person.PersonLookupViewModel
#{
var format = new dtDataTools_v10_r1.CustomFormat();
var newInitials = (Model.Income.IncomeTypeDesc.First().ToString() + Model.Income.IncomeDesc.First().ToString() + Model.Income.Income.First().ToString()).ToUpper();
}
using (Html.DSResponsiveRow(numberOfInputs: ExtensionMethods.NumberOfInputs.TwoInputs))
{
using (Html.DSCard(ExtensionMethods.Icon.CustomText, iconInitials: newInitials, color: ExtensionMethods.Colors.PrimaryBlue))
{
<div>#Model.Income.IncomeTypeDesc</div>
<div>#Model.Income.IncomeDesc</div>
<div>#Model.Income.Income</div>
}
}
There are some extensions that we have built but they are irrelevant to the issue
The line that errors out is this one:
var newInitials = (Model.Income.IncomeTypeDesc.First().ToString() + Model.Income.IncomeDesc.First().ToString() + Model.Income.Income.First().ToString()).ToUpper();
Which drives all of the extension methods on the view and as I run the debugger over it all of the parameters read null, however like I said when I run the debugger and check them in the controller they are populated properly.
Sorry about the long post but I wanted to ensure all the detail was there

This is how to pass the Object model to your Partial View
return PartialView("YourViewName", vm);
or using the Views path
return PartialView("~/YourView.cshtml", vm);
EDIT
Try starting your Action Method like this
var vm= new Person();
vm.PersonLookupViewModel = new PersonLookupViewModel();

Problem solved I had issues with some of my vb objects and had the vb person take a look at them and she fixed them.
Thank you for all the help
EDIT
What had to happen is the vb object had to be re-written and my logic was just fine as it was in the beginning. I marked the one response to my question as the answer because had it been in true MVC without vb objects attached to it, that would have worked perfectly

Model binding for nested objects

I have a class
public class Offer
{
public Int32 OfferId { get; set; }
public string OfferTitle { get; set; }
public string OfferDescription { get; set; }
}
and another class
public class OfferLocationViewModel
{
public Offer Offer { get; set; }
public Int32 InTotalBranch { get; set; }
public Int32 BusinessTotalLocation { get; set; }
}
Now in my controller I have the following
public ActionResult PresentOffers(Guid id)
{
DateTime todaysDate=Utility.getCurrentDateTime();
var rOffers=(from k in dc.GetPresentOffers(id,todaysDate)
select new OfferLocationViewModel()
{
Offer. //I dont get anything here..
}).ToList();
return PartialView();
}
Now the problem is in my controller, I can not access any property of the 'Offer' class !!
I thought, since i am creating a new OfferLocationViewModel() and this has a property of type 'Offer', I will be able to access the properties..But I can not.
Can anyone give me some idea about how to do that?

In a class initializer like new OfferLocationViewModel { ... } you can only set the immediate properties, i.e. 'Offer = new Offer()'.
You can't access the contained type's properties through the initializer.
Though you can initialize the view model's Offer to a new Offer with the given properties like this:
var rOffers = (from k in dc.GetPresentOffers(id,todaysDate)
select new OfferLocationViewModel {
Offer = new Offer {
OfferId = ...,
OfferTitle = ...,
OfferDescription = ...
}
}).ToList();

MVC3 linq joins

As a novice am trying my hands on MVC3,razor, EF I have Three connected Tables that I want to produce a view from it. In a simpleton's brief the following are about the tables
PJUsers - ID, memUID(this unique Id from membership),FirstName,LastName
PJAwards - user nominates another user for an award, this links with awardtypesID as foreign key ( awardId,bool:awardok)
PJAwartypes - (awardtypeID, awardName)
The query in the controller is like this
var lists =
from tl in db.PJawards
join u in db.PJUsers on tl.nomineeId equals u.ID into tl_u
join i in db.PJUsers on tl.nominatorId equals i.MemUID into tl_i
where tl.awardOk
orderby tl.awardDated ascending
from u in tl_u.DefaultIfEmpty()
from i in tl_i.DefaultIfEmpty()
select new
{
Status = tl.awardOk,
nomineeFname = u.FirstName,
nomineeLname = u.LastName,
award = tl.PJawards.awardName,
Dated = tl.awardDated,
nominatorFname = i.FirstName,
nominatorLname = i.LastName,
nomineeCountry = u.Citizen,
nomineeResidence = u.Residence,
awardtypeId = tl.ID
};
somewhere i read that i have to construct a model class similar to the query in the controller
{
public class AwardUserInfo
{
public AwardUserInfo() { }
public bool Status { get; set; }
public string nomineeFname { get; set; }
public string nomineeLname { get; set; }
public string award { get; set; }
public string Dated { get; set; }
public string nominatorFname { get; set; }
public string nominatorLname { get; set; }
public string nomineeCountry { get; set; }
public string nomineeResidence { get; set; }
public int awardtypeId { get; set; }
}
}
Please I learn by examples so to be able to help me assume I don't know anything

somewhere i read that i have to construct a model class similar to the query in the controller
Try this.
I guess your ef-model is similar to
So You can create a ViewModel class
public class PJAwardsViewModel
{
public int Id { get; set; }
public string NominatorFName { get; set; }
public string NomineeFname { get; set; }
public string AwardName { get; set; }
public bool IsAwarded { get; set; }
}
It will be also good if You add some service class
public class PJAwardsService
{
public static List<PJAwards> GetAll()
{
using (var context = new YourDBEntities())
{
return context.PJAwards
.Include(x => x.PJUsers)
.Include(x => x.PJUsers1)
.Include(x => x.PJAwartypes).ToList();
}
}
}
(Don't forget to write using System.Data.Entity; )
Then You can add a ViewModelHelper class
public class PJAwardsViewModelHelper
{
public static PJAwardsViewModel PopulatePJAwardsViewModel(PJAwards pjaward)
{
return new PJAwardsViewModel
{
Id = pjaward.Id,
NominatorFName = pjaward.PJUsers.FirstName,
NomineeFname = pjaward.PJUsers1.FirstName,
AwardName = pjaward.PJAwartypes.AwardName,
IsAwarded = pjaward.IsAwarded
};
}
public static List<PJAwardsViewModel> PopulatePJAwardsViewModelList(List<PJAwards> pjawardsList)
{
return pjawardsList.Select(x => PopulatePJAwardsViewModel(x)).ToList();
}
}
At the end Your controller index method will look like this
public ActionResult Index()
{
var pjawards = PJAwardsViewModelHelper.PopulatePJAwardsViewModelList(PJAwardsService.GetAll().ToList());
return View(pjawards);
}
The only thing You should do is add a view (build the project before). Choose PJAwardsViewModel as a Model class and List as a scaffold template.
Enjoy it.

Here is a step by step guide by Steven Sanderson on how to use Asp.net MVC3, EF Code First with MVCScaffolding (powershell automation).
http://blog.stevensanderson.com/2011/01/13/scaffold-your-aspnet-mvc-3-project-with-the-mvcscaffolding-package/
It is a multipart blog post takes you through the exciting journey of MVC3.
All the best.