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How to pass fragile data e.g connection string from one controller to another

Im new to asp.net core and I was trying to develop an online SQL database manager, that will work on any SQL database, after passing: ServerAddress, Login, Password and DatabaseType (my ConnectionInformation model).
Something like SSMS but online.
I want to pass my ConnectionInformation model from Login controller to Database controller.
Redirecting to action uses query string which exposes all of my data.
TempData only accepts strings and converting my model to json isn't the most elegant way to solve this problem.
Login Controller:
public class LoginController : Controller
{
private readonly ILoginLogic _loginLogic;
public LoginController(ILoginLogic loginLogic)
{
_loginLogic = loginLogic;
}
[HttpGet]
public IActionResult Index()
{
return View();
}
[HttpPost]
[ValidateAntiForgeryToken]
public IActionResult Index(ConnectionInformationViewModel connectionViewModel)
{
if (!ModelState.IsValid)
return View();
ConnectionInformation connection = Mapper.Mapper.ConnectionInformationMapper(connectionViewModel);
var connectionSuccess = _loginLogic.ConnectToDatabase(connection);
if (connectionSuccess)
return RedirectToAction("Index", "Database", connection);
else
return View(); // TODO: Return view with error or handle it in js
}
}
Database Controller:
public class DatabaseController : Controller
{
private readonly IDatabaseLogic _databaseLogic;
public DatabaseController(IDatabaseLogic databaseLogic)
{
_databaseLogic = databaseLogic;
}
public IActionResult Index(ConnectionInformation connection)
{
var databases = _databaseLogic.GetDatabases(connection);
return View(databases);
}
}
Prehaps my approach is totally wrong. My main goal is to check if I can connect to database, and if I can I want to perform query operations on that Database untill user logs out.

Well, simply, you have to persist the information some way. In that regard, there's a number of options. You could persist it in local storage on the client and actually pass it back with each further request. That works better for SPA-style apps, where you're pretty much doing everything via AJAX, though. Another technically client-side storage mechanism would be setting a session cookie with the posted connection information. Here I'm talking about explicitly setting and reading from a cookie with a "session" lifetime, not using sessions.
Or you can can actually use a true session, i.e. Session. TempData is basically just Session anyways, but here it would be inappropriate as you'd then need to ensure that the TempData is kept every time it's accessed or it won't survive the next request. If you're doing that, then you might as well just use Session and not have to worry about it.
Serialization is pretty much required no matter what you do. There's no way to persist an actual C# object instance, so you're either going to have to write it to a relational store like a database or serialize it to JSON.
One alternate solution, which avoids having to persist the actual connection information is to basically create your own connection pool. This will require a singleton-scoped class with a ConcurrentDictionary ivar and likely the use of SemaphoreSlim to lock during reads and writes of that dictionary so that you don't create and orphan connections. Then, you'd just need to assign the key to their particular connection in the dictionary client somehow, such as via Session or a cookie. This is actually a little more secure as well, as you're not persisting the database connection info past the initial post, but you might end up exhausting the available server connections if there's too many simultaneous users. Of course, that could potentially be an issue regardless. You'll also need some policy for eviction of connections. It's not the easiest setup.
Personally, I'd just stick with using Session on this one. It's secure enough, as long as you take the standard session hijacking prevention measures, and it's simple to implement. If you are building a SPA-style app, then I'd stick with local storage, as that's going to be imminently better keeping the info client-side to begin with, but it requires a bit more plumbing that way.

Passing data between Controller Actions

Hi I cant find the way to pass data between Action methods within one controller. The simplified code example is as follows:
public class HomeController : Controller
{
int latestID;
// GET: Home
public ActionResult Index()
{
latestID = 50000;
return View();
}
// GET: Generate
public ActionResult Generate()
{
// using the latestID here
return View();
}
}
Index loads when the app starts and latestID is set to 50000. But when I click button mapped to API GET request Generate, the latestID is suddenly null. I tried to implement TempData and Session but with no luck. Any help would be greatly appreciated!

I feel there are 2 possibilities here i.e. the value to be retrieved is for a user session or its global across all the users using the website.
If the value is user specific then it can be managed through session stage management like Viewbag. Or if this value is expected to be maintained on the server side alone then it needs to be retrieved again through some persistence mechanism like database or memory cache.
If the value is common across all the users using the Website then it can be achieved through the Dependency Injection of a singleton object (this can be a database manager or cache manager again or a simple in memory object). The static objects can be used as well but it wouldn't be ideal as the application wouldn't support horizontal scalability across instances.

Dealing with Session timeout in ASP.NET MVC

I am working on a MVC application and I have a requirement of dealing with errors and session timeouts by redirecting the user to different error pages based on few parameters in the query string.
The issue I am facing is that i tried to implement this by saving the required parameters from querystring into a session and then redirecting to error pages. But before every HttpGet and Post action in my controllers I am checking if session is active.
So in case of a situation where session values are lost and not able to read them.
How can I implement this thing in any other way?

You need to check whether the session exists, has the fields you expect and is active. If the session does not exist or does not have a fields you expect, then handle the case when the session does not exist yet/expired. If it is not active, then handle the case when the session is no longer active. If everything is ok, then handle the request normally. If the session expired, then handle it as expired.

to check about session, you can use an ActionFilter like this:
public class SessionActiveFilterAttribute : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
var activeSession = Session["user"];
if (activeSession == null)
//Here, do a redirect
base.OnActionExecuting(filterContext);
}
}
Also, you can use a third option to save the session, like Redis Cache http://blogs.msdn.com/b/webdev/archive/2014/05/12/announcing-asp-net-session-state-provider-for-redis-preview-release.aspx

I know this is a dead story now. But I post this answer for the new comers. Please see the nice tutorial in codeproject about how to check session values in Action Filters.
In a dynamic web application, the session is crucial to hold the information of current logged in user identity/data. So someone without authentication cannot have access to some Page or any ActionResult, to implement this kind of functionality, we need to check session exists (is not null) in every action which required authentication.So, the general method is as follows:
[HttpGet]
public ActionResult Home()
{
if(Session["ID"] == null)
return RedirectToAction("Login","Home");
}
We have to check the above 2 statements each time and in each ActionResult, but it may cause 2 problems.
Repeat Things: As per the good programming stranded, we don't have to repeat the things. Create a module of common code and access it multiple times/repeatedly
Code missing: We have to write code multiple times so it might happen some time we forget to write code in some method or we missed it.
How To Avoid?
The ASP.NET MVC provides a very great mechanism i.e., Action Filters. An action filter is an attribute. You can apply most action filters to either an individual controller action or an entire controller.
If you want to know more about action filter, please click here.
So we will create a custom Action Filter that handles session expiration and if session is null, redirect to Login Action.
Create a new class in your project and copy the following code:
namespace YourNameSpace
{
public class SessionTimeoutAttribute : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
HttpContext ctx = HttpContext.Current;
if (HttpContext.Current.Session["ID"] == null)
{
filterContext.Result = new RedirectResult("~/Home/Login");
return;
}
base.OnActionExecuting(filterContext);
}
}
}
Now our Action Filter is created and we are ready to use it. The following code will show you how we can apply attribute to Action or to complete controller.
Apply to Action
[HttpGet]
[SessionTimeout]
public ActionResult MyProfile()
{
return View();
}
Apply to Controller
[SessionTimeout]
public class HomeController : Controller
{
}
Now all actions of Home Controller will check for session when hit with the help of Action Filter. So we have reduced the code and repetitive things. This is the benefits of Action Filters.

Keeping controller in scope

Yesterday i was working on my asp.net mvc application where i was trying to cache some data in a field while a certain controller was in scope. The field kept clearing every time a new view got opened.
Question:
Is it possible to keep your Controller in scope while you're browsing Views that are handled by said Controller?
private static List<string> _listOfStrings;
[Authorize]
public ActionResult ToView1()
{
_listOfStrings = new List<String>(){"test","test2"};
var model = new Model();
return View(model);
}
[Authorize]
public ActionResult FromView1ToView2()
{
var model = new Model(_listOfStrings);
//the issue at hand is that '_listOfStrings' is not persisted.
return View(model);
}
Anyone got an idea if this is possible? (The list is big, so i would prefer not sending it through the model into the view and vice versa)

You need to read about an ASP.NET MVC lifecycle.
Short answer: no, you can't cause Controller is destroyed after a call of an action. Detail answer: you can store (cache) data in a TempData or in a Session properties.

_listOfStrings is a different variable to listOfStrings. You are not writing to or reading from the static field. In the code you have presented, _listOfStrings is not even defined.
Use one static variable and this code will work.

Pass complex object with redirect in ASP.NET MVC?

Hi,
I have a action that looks like this :
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Register(AdRegister adRegister, IEnumerable<HttpPostedFileBase> files)
The AdRegister is a complex class and I need to pass this in to a redirect method further down in the Register action, like this :
return this.RedirectToAction("Validate", adRegister);
The Validate action looks like this :
public ActionResult Validate(AdRegister adRegister)
I do know that I can pass simple parameters but in this case it´s a complex object. This example do not work, the adRegister´s properties will be null.
Is this posible and if so, how?
BestRegards
More Information : Register action will take the adRegister and do som magic on it, then It will be sent to the Validate action. The Validate action will return a validation page to the user. When the user hit the grant button the adRgister will be filled from the form and then sent to the vValidate post where it will be saved. I have looked in to place the adRegister in cache or database temporarily but it will be better if I could simple pass it to the next action.

One possibility would be to pass the simple properties in the query string:
return RedirectToAction(
"Validate",
new {
foo = adRegister.Foo,
bar = adRegister.Bar,
... and so on for all the properties you want to send
}
);
Another possibility is to store it in TempData (for the lifetime of the redirect) or Session (for the lifetime of the ASP.NET session):
TempData["adRegister"] = adRegister;
return RedirectToAction("Validate");
and then retrieve it from TempData:
public ActionResult Validate()
{
adRegister = TempData["adRegister"] as AdRegister;
...
}
Yet another possibility (and the one I would recommend you) is to persist this object in the POST method in your datastore:
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Register(AdRegister adRegister, IEnumerable<HttpPostedFileBase> files)
{
...
string id = Repository.Save(adRegister);
return RedirectToAction("Validate", new { id = adRegister.Id });
}
and then fetch it from the data store after you redirect:
public ActionResult Validate(string id)
{
AdRegister adRegister = Repository.Get(id);
...
}

an idea would probably create a session variable and pass around a Key that references that session variable if the object is required acorss a few views?

ASP.NET MVC's tempdata should be perfect for this.
That said, TempData or Session is one option, but has some downsides like being quite violate and oftentimes murky or difficult to debug. What might be preferable is to "stash" the temporary value in a persistent store, such as the user's profile or your own database, then pass a key through the validate method which can then load the data from said store. This also opens up the possibility of recovering abandoned carts and such.