Cannot Use LINQ-Method In Razor View ASP.Net

Question

I call a model in view.cshtml like this:

@model IEnumerable<Spiirit_Project.Models.Deliverable>

Then I use this LINQ-method in view.cshtml so:

@{ var a = Model.Where(p => p.deliverable_research_year_id == 169).Count(); }

When I run my project, there is error: "Value cannot be null. Parameter name: source".

my "Deliverable" Table is not null but I get this error. How to fix this error?

there is my controller:

public ActionResult CreateDeliverable(int? idResearch, int? idBaseline, int? idYear){
ViewBag.IdResearch = idResearch;
ViewBag.IdBaseline = idBaseline;
ViewBag.IdYear = idYear;
ViewBag.Year = db.Deliverable_Research_Years.Find(idYear);
ViewBag.Deliverable = db.Deliverables.ToList();

return View();
}

Your model is null, regardless of your claim. If you want to prove us wrong, add a screenshot of the Visual Studio debugger with the value of Model. — Camilo Terevinto
– Camilo Terevinto, Commented Jan 10, 2019 at 2:04
Please add the controller code to your question (not in comments). — mjwills
– mjwills, Commented Jan 10, 2019 at 2:17
return View(db.Deliverables.ToList()); - and no need to assign to ViewBag.Deliverable. Then have a read of stackoverflow.com/questions/6242810/why-is-the-view-model-null . — mjwills
– mjwills, Commented Jan 10, 2019 at 2:18
It is better to use Model than ViewBag - stackoverflow.com/questions/21716953/… — mjwills
– mjwills, Commented Jan 10, 2019 at 4:32
Best practice is not ViewBag. Read the link I provided. If you need multiple objects, then create your own AghnatModel class with multiple properties (for each of things you need). Then use @model Spiirit_Project.Models.AghnatModel. — mjwills
– mjwills, Commented Jan 10, 2019 at 4:41

Aghnat Atqiya · Accepted Answer · 2019-01-10 02:51:33Z

3

@mjwills tell me in comment to pass in the model to the view. So I change my controller like this:

public ActionResult CreateDeliverable(int? idResearch, int? idBaseline, int? idYear){
ViewBag.IdResearch = idResearch;
ViewBag.IdBaseline = idBaseline;
ViewBag.IdYear = idYear;
ViewBag.Year = db.Deliverable_Research_Years.Find(idYear);

return View(db.Deliverables.ToList());
}

This is work correctly!

answered Jan 10, 2019 at 2:51

Aghnat Atqiya

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Comments

Richard Schneider · Accepted Answer · 2019-01-10 01:59:31Z

-2

Try

@{ var a = Model?.Where(p => p.deliverable_research_year_id == 169).Count() ?? 0; }

This is assuming that deliverable_research_year_id is NOT a nullable type.

answered Jan 10, 2019 at 1:59

Richard Schneider

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1 Comment

Camilo Terevinto Over a year ago

This assumes that the OP can use C# 6+ and it doesn't solve any kind of problems, it just hides a bug.

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