I have never seen this before and am stumped. I have the following controller sequence:
/// <summary>
/// Helper method to store offerId to TempData
/// </summary>
/// <param name="offerId"></param>
private void StoreOfferInTempData(string offerId)
{
if (TempData.ContainsKey(SelectedOfferKey))
TempData.Remove(SelectedOfferKey);
TempData.Add(SelectedOfferKey, offerId);
}
[HttpPost]
[AllowAnonymous]
public virtual ActionResult Step1(MyViewModel model)
{
if (ModelState.IsValid)
{
StoreOfferInTempData(model.SelectedOfferId);
return RedirectToAction(MVC.Subscription.Register());
}
MySecondViewModel model2 = new MySecondViewModel { OfferId = model.SelectedOfferId };
return View(model2);
}
[HttpGet]
[AllowAnonymous]
public virtual ActionResult Register()
{
string offerId = TempData[SelectedOfferKey] as string; //we get a valid value here
... error handling content elided ...
RegisterViewModel model = new RegisterViewModel { OfferId = offerId };
return View(model);
}
[HttpPost]
[AllowAnonymous]
public virtual ActionResult Register(RegisterViewModel model)
{
if (ModelState.IsValid)
{
CreateCustomerResult result = CustomerService.CreateAccount(model.Email, model.NewPassword);
if (result.Success)
{
... content elided; storing customer to Session ...
MyMembershipProvider.PersistUserCookie(result.Principal, true);
//need to store our selected OfferId again for use by the next step
StoreOfferInTempData(model.OfferId);
return RedirectToAction(MVC.Subscription.Payment());
}
model.ErrorMessage = result.ErrorMessage;
}
return View(model);
}
[HttpGet]
public ActionResult Payment()
{
string offerId = TempData[SelectedOfferKey] as string; //this is null???
... content elided ...
return View(model);
}
The first round of storage to TempData behaves as expected. The value is present in the subsequent HttpGet method and is marked for deletion such that it is no longer there when I go to add it again. However, on the third HttpGet method, it returns null.
I have tried using different Keys for each round with no change. I can assure you that at no time other than those displayed am I checking TempData, so I see no way the value would be marked for deletion somehow. Also, it fails in the Payment method whether it has an [AllowAnonymous] attribute or not (so not due to any http to https switch or anything like that.
Seems like it must be something very simple, but my searches have turned up nothing. Any help greatly appreciated.
UPDATE: On further inspection, it seems my whole context is hosed on this step, for some reason. We're using IoC in the controllers, but none of the IoC-instantiated items are there. The mystery deepens.
The lifespan of TempData is only until it's read back out or the next request has processed (which ever comes first). You shouldn't be relying on TempData if you're going in to two (or three) requests. Instead, use the session or a database.
The purpose of TempData is to hand-off information between requests not to perpetuate until you clear it (that's what sessions are for).
Aha! Well, this is obscure enough that I hope it helps someone else. Turns out, I had forgotten to run my T4MVC.tt file after creating the Payment() actions, so the RedirectToAction taking an MVC.Subscription.Payment() action was not instantiating the controller properly. I'm not clear on all the underlying magic here, but if you run into this and are using T4MVC.tt, make sure you ran it!
Comments on why this would be are welcome.
Use TempData.Keep("key") to retain values between multiple post-backs
Related
I am quite new to ASP .NET core, so please help. I would like to avoid database round trip for ASP .NET core application. I have functionality to dynamically add columns in datagrid. Columns settings (visibility, enable, width, caption) are stored in DB.
So I would like to store List<,PersonColumns> on server only for actual session. But I am not able to do this. I already use JsonConvert methods to serialize and deserialize objects to/from session. This works for List<,Int32> or objects with simple properties, but not for complex object with nested properties.
My object I want to store to session looks like this:
[Serializable]
public class PersonColumns
{
public Int64 PersonId { get; set; }
List<ViewPersonColumns> PersonCols { get; set; }
public PersonColumns(Int64 personId)
{
this.PersonId = personId;
}
public void LoadPersonColumns(dbContext dbContext)
{
LoadPersonColumns(dbContext, null);
}
public void LoadPersonColumns(dbContext dbContext, string code)
{
PersonCols = ViewPersonColumns.GetPersonColumns(dbContext, code, PersonId);
}
public static List<ViewPersonColumns> GetFormViewColumns(SatisDbContext dbContext, string code, Int64 formId, string viewName, Int64 personId)
{
var columns = ViewPersonColumns.GetPersonColumns(dbContext, code, personId);
return columns.Where(p => p.FormId == formId && p.ObjectName == viewName).ToList();
}
}
I would like to ask also if my approach is not bad to save the list of 600 records to session? Is it better to access DB and load columns each time user wants to display the grid?
Any advice appreciated
Thanks
EDIT: I have tested to store in session List<,ViewPersonColumns> and it is correctly saved. When I save object where the List<,ViewPersonColumns> is property, then only built-in types are saved, List property is null.
The object I want to save in session
[Serializable]
public class UserManagement
{
public String PersonUserName { get; set; }
public Int64 PersonId { get; set; }
public List<ViewPersonColumns> PersonColumns { get; set; } //not saved to session??
public UserManagement() { }
public UserManagement(DbContext dbContext, string userName)
{
var person = dbContext.Person.Single(p => p.UserName == userName);
PersonUserName = person.UserName;
PersonId = person.Id;
}
/*public void PrepareUserData(DbContext dbContext)
{
LoadPersonColumns(dbContext);
}*/
public void LoadPersonColumns(DbContext dbContext)
{
LoadPersonColumns(dbContext, null);
}
public void LoadPersonColumns(DbContext dbContext, string code)
{
PersonColumns = ViewPersonColumns.GetPersonColumns(dbContext, code, PersonId);
}
public List<ViewPersonColumns> GetFormViewColumns(Int64 formId, string viewName)
{
if (PersonColumns == null)
return null;
return PersonColumns.Where(p => p.FormId == formId && p.ObjectName == viewName).ToList();
}
}
Save columns to the session
UserManagement userManagement = new UserManagement(_context, user.UserName);
userManagement.LoadPersonColumns(_context);
HttpContext.Session.SetObject("ActualPersonContext", userManagement);
HttpContext.Session.SetObject("ActualPersonColumns", userManagement.PersonColumns);
Load columns from the session
//userManagement build-in types are set. The PersonColumns is null - not correct
UserManagement userManagement = session.GetObject<UserManagement>("ActualPersonContext");
//The cols is filled from session with 600 records - correct
List<ViewPersonColumns> cols = session.GetObject<List<ViewPersonColumns>>("ActualPersonColumns");
Use list for each column is better than use database.
you can't create and store sessions in .net core like .net framework 4.0
Try Like this
Startup.cs
public void ConfigureServices(IServiceCollection services)
{
//services.AddDbContext<GeneralDBContext>(options => options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));
services.AddMvc().AddSessionStateTempDataProvider();
services.AddSession();
}
Common/SessionExtensions.cs
sing Microsoft.AspNetCore.Http;
using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
namespace IMAPApplication.Common
{
public static class SessionExtensions
{
public static T GetComplexData<T>(this ISession session, string key)
{
var data = session.GetString(key);
if (data == null)
{
return default(T);
}
return JsonConvert.DeserializeObject<T>(data);
}
public static void SetComplexData(this ISession session, string key, object value)
{
session.SetString(key, JsonConvert.SerializeObject(value));
}
}
}
Usage
==> Create Session*
public IActionResult Login([FromBody]LoginViewModel model)
{
LoggedUserVM user = GetUserDataById(model.userId);
//Create Session with complex object
HttpContext.Session.SetComplexData("loggerUser", user);
return Json(new { status = result.Status, message = result.Message });
}
==> Get Session data*
public IActionResult Index()
{
//Get Session data
LoggedUserVM loggedUser = HttpContext.Session.GetComplexData<LoggedUserVM>("loggerUser");
}
Hope this is helpful. Good luck.
This is an evergreen post, and even though Microsoft has recommended serialisation to store the object in session - it is not a correct solution unless your object is readonly, I have a blog explaining all scenario here and i have even pointed out the issues in GitHub of Asp.Net Core in issue id 18159
Synopsis of the problems are here:
A. Serialisation isn't same as object, true it will help in distributed server scenario but it comes with a caveat that Microsoft have failed to highlight - that it will work without any unpredictable failures only when the object is meant to be read and not to be written back.
B. If you were looking for a read-write object in the session, everytime you change the object that is read from the session after deserialisation - it needs to be written back to the session again by calling serialisation - and this alone can lead to multiple complexities as you will need to either keep track of the changes - or keep writing back to session after each change in any property. In one request to the server, you will have scenarios where the object is written back multiple times till the response is sent back.
C. For a read-write object in the session, even on a single server it will fail, as the actions of the user can trigger multiple rapid requests to the server and not more than often system will find itself in a situation where the object is being serialised or deserialised by one thread and being edited and then written back by another, the result is you will end up with overwriting the object state by threads - and even locks won't help you much since the object is not a real object but a temporary object created by deserialisation.
D. There are issues with serialising complex objects - it is not just a performance hit, it may even fail in certain scenario - especially if you have deeply nested objects that sometimes refer back to itself.
The synopsis of the solution is here, full implementation along with code is in the blog link:
First implement this as a Cache object, create one item in IMemoryCache for each unique session.
Keep the cache in sliding expiration mode, so that each time it is read it revives the expiry time - thereby keeping the objects in cache as long as the session is active.
Second point alone is not enough, you will need to implement heartbeat technique - triggering the call to session every T minus 1 min or so from the javascript. (This we anyways used to do even to keep the session alive till the user is working on the browser, so it won't be any different
Additional Recommendations
A. Make an object called SessionManager - so that all your code related to session read / write sits in one place.
B. Do not keep very high value for session time out - If you are implementing heartbeat technique, even 3 mins of session time out will be enough.
This first method is fine. But when I add the second method the body of the SWAGGER UI is a bunch of html gibberish. And I creating the route the wrong way?
// GET api/checklist/1288
[HttpGet("{id}")]
public async Task<IActionResult> Get(int id)
{
var model = _checkListService.Get(id);
return Ok(model);
}
// http://localhost:64783/api/checklist/GetDelinquentItems?id=1288
[Route("GetDelinquentItems")]
public async Task<IActionResult> GetDelinquentItems(int id)
{
var model = _checkListService.GetDelinquentItems(id);
return Ok(model);
}
That 'html gibberish' (indeed not the most elegant way to show an error) still contains some useful information. The first line says:
500 internal server error
and in the last three lines you can read:
Ambiguos HTTP method for action...CheckListController.GetDelinquentItems... Actions require explicit HttpMethod binding for Swagger
therefore another
[HttpGet("{id}")]
before the GetDelinquentItems() method should solve the problem.
I have a site which have many action like article, blog, news, stories, myths, books, audio, video.
Now I want if i pass a query string in index action like
wwww.mysite.com/english
then every action must be have this parameter automatically like
wwww.mysite.com/article/englishwwww.mysite.com/blog/englishwwww.mysite.com/news/englishwwww.mysite.com/stories/englishwwww.mysite.com/myths/englishwwww.mysite.com/books/englishwwww.mysite.com/audio/englishwwww.mysite.com/video/english
Please help me and suggest a good way
Store the passed passed parameter in a session variable and then access on each action. Example:
public ActionResult Index(string lang)
{
Session["Language"]= lang;
return View();
}
And then fetch in other actions like:
public ActionResult News()
{
string lang= Session["Language"].ToString();
// Do something with the lang...
return View();
}
I'm working on upgrading an application from MVC3 to MVC4 and noticed something that I assumed (hoped?) would "just work".
CODE:
[OutputCache(Duration = 600, VaryByParam = "none")]
public ActionResult Index()
{
return View();
}
This is a textbook caching example for ASP.Net. Whenever a browser hits the page, it checks the cache to see if something exists, generates the view if not, and then sends the cached results.
This works great; however, playing around with the Mobile view functionality of MVC4, I noticed that the above code does not check to see if the Request is from a Mobile Device. So if I hit that route on a desktop, the desktop view will be displayed on my phone until cache is invalidated. The reverse is true as well (if I first hit the page with a phone, the desktop will then see the mobile view instead).
Is there a parameter that I could use to make this work like I hoped or am I looking at building a customer OutputCacheProvider?
After a bit more digging, I found a solution to the issue.
Updated Controller Action
[OutputCache(Duration = 600, VaryByCustom = "IsMobile")]
public ActionResult Index()
{
return View();
}
Override GetVaryByCustomString in Global.asax
public override string GetVaryByCustomString(HttpContext context, string custom)
{
if (custom.ToLowerInvariant() == "ismobile" && context.Request.Browser.IsMobileDevice)
{
return "mobile";
}
return base.GetVaryByCustomString(context, custom);
}
This is Correct GetVaryByCustomString method
public override string GetVaryByCustomString(HttpContext context, string custom)
{
if (custom.ToLowerInvariant() == "ismobile")
{
return context.GetVaryByCustomStringForOverriddenBrowser();
}
return base.GetVaryByCustomString(context, custom);
}
I'm running two instances of my application. In one instance, I save one of my entities. When I check the RavenDB (http://localhost:8080/raven), I can see the change. Then, in my other client, I do this (below), but I don't see the changes from the other application. What do I need to do in order to get the most recent data in the DB?
public IEnumerable<CustomVariableGroup> GetAll()
{
return Session
.Query<CustomVariableGroup>()
.Customize(x => x.WaitForNonStaleResults());
}
Edit: The code above works if I try to make a change and get a concurrency exception. After that, when I call refresh (which invokes the above code), it works.
Here is the code that does the save:
public void Save<T>(T objectToSave)
{
Guid eTag = (Guid)Session.Advanced.GetEtagFor(objectToSave);
Session.Store(objectToSave, eTag);
Session.SaveChanges();
}
And here is the class that contains the Database and Session:
public abstract class DataAccessLayerBase
{
/// <summary>
/// Gets the database.
/// </summary>
protected static DocumentStore Database { get; private set; }
/// <summary>
/// Gets the session.
/// </summary>
protected static IDocumentSession Session { get; private set; }
static DataAccessLayerBase()
{
if (Database != null) { return; }
Database = GetDatabase();
Session = GetSession();
}
private static DocumentStore GetDatabase()
{
string databaseUrl = ConfigurationManager.AppSettings["databaseUrl"];
DocumentStore documentStore = new DocumentStore();
try
{
//documentStore.ConnectionStringName = "RavenDb"; // See app.config for why this is commented.
documentStore.Url = databaseUrl;
documentStore.Initialize();
}
catch
{
documentStore.Dispose();
throw;
}
return documentStore;
}
private static IDocumentSession GetSession()
{
IDocumentSession session = Database.OpenSession();
session.Advanced.UseOptimisticConcurrency = true;
return session;
}
}
Lacking more detailed information and some code, I can only guess...
Please make sure that you call .SaveChanges() on your session. Without explicitly specifiying an ITransaction your IDocumentSession will be isolated and transactional between it's opening and the call to .SaveChanges. Either all operations succeed or none. But if you don't call it all your previous .Store calls will be lost.
If I was wrong, please post more details about your code.
EDIT: Second answer (after additional information):
Your problem has to do with the way RavenDB caches on the client-side. RavenDB by default caches every GET request throughout a DocumentSession. Plain queries are just GET queries (and no, it has nothing to do wheter your index in dynamic or manually defined upfront) and therefore they will be cached. The solution in your application is to dispose the session and open a new one.
I suggest you rethink your Session lifecycle. It seems that your sessions live too long, otherwise this concurrency wouldn't be an issue. If you're building a web-application I recommend to open and close the session with the beginning and the end of your request. Have a look at RaccoonBlog to see it implemented elegantly.
Bob,
It looks like you have but a single session in the application, which isn't right. The following article talks about NHibernate, but the session management parts applies to RavenDB as well:
http://archive.msdn.microsoft.com/mag200912NHibernate
This code is meaningless:
Guid eTag = (Guid)Session.Advanced.GetEtagFor(objectToSave);
Session.Store(objectToSave, eTag);
It basically a no op, but one that looks important. You seems to be trying to work with a model where you have to manually manage all the saves, don't do that. You only need to manage things yourself when you create a new item, that is all.
As for the reason you get this problem, here is a sample:
var session = documentStore.OpenSession();
var post1 = session.Load<Post>(1);
// change the post by another client
post2 = session.Load<Post>(1); // will NOT go to the server, will give the same instance as post1
Assert.ReferenceEquals(post1,post2);
Sessions are short lived, and typically used in the scope of a single form / request.