CODEWITHSUNDEEP
c#asp.net-mvcasp.net-mvc-3
SCS
SCS

Reputation: 639

Single action requiring instantiation of repository or NullReferenceException occurs

I currently have a controller with several actions, but I've run into a problem with a single action that seems to require the instantiation of the repository within the action itself, or else I get a NullReferenceException during runtime--the action itself doesn't appear to be any different than the other actions in the controller. This is what I have so far:

    public class PatentController : Controller
    {
        IRepositoryExtension patentRepository;

        public PatentController()
        {
            PatentRepository patentRepository = new Proj.Data.PatentRepository();
        }

        //Constructor for unit test project
        public PatentController(IRepositoryExtension repository)
        {
            patentRepository = repository;
        }

        public ActionResult Index()
        {
            return View();
        }

        //Other actions removed for brevity

        public ActionResult DetailsPartial(string id)
        {
            //If this PatentRepository is removed, NullReferenceException occurs
            PatentRepository patentRepository = new Proj.Data.PatentRepository();
            USPTOPatent usptoPatent = patentRepository.GetPatent(id);
            return PartialView("DetailsPartial", usptoPatent);
        }

Is there a particular reason why I need the repository instantiated in the action for it to work? This is the error I get if I comment it out:

Object reference not set to an instance of an object.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:

Line 155: //PatentRepository patentRepository = new Proj.Data.PatentRepository(); Line 156: USPTOPatent usptoPatent = patentRepository.GetPatent(id); Line 157:
return PartialView("DetailsPartial", usptoPatent); Line 158: }

Upvotes: 0

Views: 174

Answers (2)

Moo-Juice
Moo-Juice

Reputation: 38800

Your default constructor assigns the result of the new to a local variable, that will take precedence over the one declared at class scope. Therefore, when the controller is created in this way, the member variable parentRepository has not been initialised.

Change the default ctor to:

 public PatentController()
    {
        /*PatentRepository*/ patentRepository = new Proj.Data.PatentRepository();
    }

Upvotes: 4

Frazell Thomas
Frazell Thomas

Reputation: 6111

Is GetPatent() a static method that returns an instance of USPTOPatent? It looks like that method isn't static.

If the method isn't static the object will need to be instantiated to be utilized.

See: Static and Instance Members.

If the method is static ensure that it is returning an object on all code paths.

Upvotes: 1

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