Object variable empty but RawView contains data in Core MVC project.

Question

Taking my first crack at DI in a MVC project using Core 3.1, and I'm stumped on a fairly basic question. I know I'm biting off several new things in one gulp, but I've done a lot of reading and sample projects so I feel like I understand what SHOULD be happening.

I'm creating an instance of a Service Layer in Startup.cs, and it appears to initialize properly.

The first time my HomeController Index method calls the ServiceLayer, everything seems to work correctly, as I can set and read some Instance vars in the ServiceLayer and it returns data to the Controller as expected.

But the next time a controller method makes a call to the ServiceLayer, the simple instance variables (strings) are still set as expected, but objects that I expected to be persisted in the ServiceLayer are null.

Here's a few snips that I think show my entire setup. I hope I'm missing something easy, but it behaves as if object variables simply don't persist, which really makes no sense.

Startup.cs

        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }
        public Startup(IConfiguration configuration, IWebHostEnvironment env)
        {
            Configuration = configuration;
            Env = env;
        }

        public IWebHostEnvironment Env { get; set; }
        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddRazorPages();
            services.AddSingleton<ServiceMgr>();
            services.AddAutoMapper(typeof(Startup));

            //if (Env.IsDevelopment()
            //{

            //}
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env, ILoggerFactory loggerFactory)
        {
            loggerFactory.AddLog4Net();

            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }
            app.UseHttpsRedirection();
            app.UseStaticFiles();

            app.UseRouting();

            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
                endpoints.MapControllerRoute("default", "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }

HomeController:

    public IActionResult Index()
    {
        _svcMgr.Test();

        _svcMgr._testStr = "Updated";
        mvm = _svcMgr.GetMainViewModel();
        mvm.JobBatch.StatusMsg = "Test Not started";


        return View(mvm);
    }
   public IActionResult DisplayJobs(string BatchID)
    {
        log.Info("HomeController.DisplayJobs - In Display Jobs");
        mvm = _svcMgr.GetMainViewModel(BatchID);
        //mvm.JobBatch = new JobBatchViewModel(BatchID); //** Fix this ASAP to do Read from Repo

        return PartialView("Jobs", mvm.JobBatch);
    }

ServiceMgr:

public class ServiceMgr
{
    Guid currentRequest = new Guid();

    ILog log = LogManager.GetLogger("Perf");

    private IMapper _mapper;

    public string _testStr = "";
    private ViewModels.JobMainViewModel _jmvm;


    public JobMainViewModel Jmvm { get => _jmvm; set => _jmvm = value; }

    public ServiceMgr(IMapper mapper)
    {
        _mapper = mapper;
        _jmvm = new ViewModels.JobMainViewModel();

    }

    public JobMainViewModel GetMainViewModel()
    {
        _jmvm.JobBatchList.BatchListItems = MapJobBatchList(GetJobBatchList());
        if (_jmvm.JobBatchList.SelectedID != -1)
        {
            string batchID = _jmvm.JobBatchList.SelectedID.ToString();

            _jmvm.JobBatch = _jmvm.JobBatchList.Find(t => t.ID == batchID);
            List<JobItem> jbi = GetJobBatchItems(batchID);

        }
        return _jmvm;

    }
    public JobMainViewModel GetMainViewModel(string BatchID)
    {
        //HERE is where the trouble shows up ****
        _jmvm.JobBatch = _jmvm.JobBatchList.Find(t => t.ID == BatchID);
        List<JobItem> jbi = GetJobBatchItems(BatchID);

        _jmvm.JobBatch.JobItems = MapJobBatchItems(jbi);

        return _jmvm;

    }

The first call to GetMainViewModel() seems to work great. I can see that _testStr gets and stays set to "Updated" by the Index() call. But once I do something on the Index page (selecting something from a dropdown and returning 'BatchID' via jQuery) and reach the DisplayJobs() controller method, things go wrong. If I set a breakpoint on the line starting with "//HERE" in ServiceMgr, I see that _testStr is still set to 'Updated', so I THINK I have the same instance of ServiceMgr, but the objects look like a new instance. If I look at _jmvm.JobBatchList, it is empty, but RawView is correctly populated with the object contents from the first call into ServiceMgr, which is what I want to access.

I have no idea what's going on there, but since I can't see that contents in the object itself I don't know how to proceed.

Answer 1

Sorry, found the problem - a combo of bad object naming and a nesting issue.