Can't pass data into view layer in asp.net : NullReferenceException: Object reference not set to an instance of an object

Question

I'm new in the asp.net and try to create simle project, but have the iisue on the first steps: I have the NullReferenceException: Object reference not set to an instance of an object. in the view layer.

Packages in solution:

Startup.cs:

  public void ConfigureServices(IServiceCollection services)
  {
      services.AddControllersWithViews();
      services.AddMvc();
      services.AddTransient<ICars, MockCars>();
      services.AddTransient<ICategories, MockCategories>();
      services.AddMvc(option => option.EnableEndpointRouting = false);
  }

  public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
  {
      app.UseDeveloperExceptionPage();
      app.UseStatusCodePages();
      app.UseStaticFiles();
      app.UseMvcWithDefaultRoute();
  }

Controller:

public ViewResult List()
  {
      IEnumerable<Car> result = _cars.Cars; //not null - checked
      return View(result);
  }

View:

    @page
    @using Shop.Models
    @model IEnumerable<Car>
    
    @{
        Layout = null;
    }
    
    <!DOCTYPE html>
    <html>
    <head>
        <title></title>
    </head>
    <body>
    <div>
        <h2>All cars</h2>
        @{
            foreach (var car in Model)//    <----    NullReferenceException 
            {
                <div>
                    <h2>Model: @car.name. @car.shortDescriotion</h2>
                    <p>Price: @car.price.ToString("c")</p>
                </div>
            }
        }
    </div>
    </body>
    </html>

Exception:

    > NullReferenceException: Object reference not set to an instance of an
    > object. AspNetCore.Views_Cars_List.get_Model()
    > AspNetCore.Views_Cars_List.<ExecuteAsync>b__8_1() in List.cshtml
    > +
    >         foreach (var car in Model) Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext.SetOutputContentAsync()
    > AspNetCore.Views_Cars_List.ExecuteAsync() in List.cshtml
    > +
    >     Layout = null; Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageCoreAsync(IRazorPage
    > page, ViewContext context)
    > Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageAsync(IRazorPage
    > page, ViewContext context, bool invokeViewStarts)
    > Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderAsync(ViewContext
    > context)
    > Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ViewContext
    > viewContext, string contentType, Nullable<int> statusCode)
    > Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ViewContext
    > viewContext, string contentType, Nullable<int> statusCode)
    > Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ActionContext
    > actionContext, IView view, ViewDataDictionary viewData,
    > ITempDataDictionary tempData, string contentType, Nullable<int>
    > statusCode)
    > Microsoft.AspNetCore.Mvc.ViewFeatures.ViewResultExecutor.ExecuteAsync(ActionContext
    > context, ViewResult result)
    > Microsoft.AspNetCore.Mvc.ViewResult.ExecuteResultAsync(ActionContext
    > context)
    > Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResultFilterAsync>g__Awaited|29_0<TFilter,
    > TFilterAsync>(ResourceInvoker invoker, Task lastTask, State next,
    > Scope scope, object state, bool isCompleted)
    > Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResultExecutedContextSealed
    > context)

The video tutorial I followed all works well, but not in my case. Where could I was wrong?

Vlad DX · Accepted Answer · 2020-11-22 20:50:29Z

When you use the @page directive, you tell that this view is a Razor Page View.

@page makes the file into an MVC action - which means that it handles requests directly, without going through a controller

Microsoft Docs: Introduction to Razor Pages in ASP.NET Core / Razor Pages

But you probably want to use ASP.NET Core MVC View:

In ASP.NET Core MVC the View is an HTML template with embedded Razor markup.

Microsoft Docs: Views in ASP.NET Core MVC

So, the fix should be simple. Remove the @page directive from your view and it should work.

@using Shop.Models
@model IEnumerable<Car>
    
@{
    Layout = null;
}
    
<!DOCTYPE html>
<html>
<head>
    <title></title>
</head>
<body>
<div>
    <h2>All cars</h2>
    @{
        foreach (var car in Model)
        {
            <div>
                <h2>Model: @car.name. @car.shortDescriotion</h2>
                <p>Price: @car.price.ToString("c")</p>
            </div>
        }
    }
</div>
</body>
</html>

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