ViewBag ViewData and TempData

Question

Could any body explain  when to use    TempData ViewBag ViewData   I have a  requirement  where I need to set a value in a controller one  that controller will redirect to Controller Two and Controller Two will render the View   I have tried to use ViewBag  the value gets lost by the time I reach Controller Two   Can I know when to use and advantages or disadvantages    Thanks

User · Answer

ViewBag  ViewData  TempData and View State in MVC  http   royalarun blogspot in 2013 08 viewbag-viewdata-tempdata-and-view html  ASP NET MVC offers us three options ViewData  VieBag and TempData for passing data from controller to view and in next request  ViewData and ViewBag are almost similar and TempData performs additional responsibility    Similarities between ViewBag  amp  ViewData       Helps to maintain data when you move from controller to view  Used to   pass data from controller to corresponding view  Short life means   value becomes null when redirection occurs  This is because their goal   is to provide a way to communicate between controllers and views  It   s   a communication mechanism within the server call    Difference between ViewBag  amp  ViewData      ViewData is a dictionary of objects that is derived from   ViewDataDictionary class and accessible using strings as keys  ViewBag   is a dynamic property that takes advantage of the new dynamic features   in C  4 0  ViewData requires typecasting for complex data type and   check for null values to avoid error  ViewBag doesn   t require   typecasting for complex data type    ViewBag  amp  ViewData Example   public ActionResult Index            ViewBag Name    Arun Prakash       return View           public ActionResult Index           ViewData  Name      Arun Prakash       return View         In View  we call like below    ViewBag Name     ViewData  Name     TempData      Helps to maintain data when you move from one controller to other   controller or from one action to other action  In other words when you   redirect     Tempdata    helps to maintain data between those redirects    It internally uses session variables  TempData is meant to be a very   short-lived instance  and you should only use it during the current   and the subsequent requests only   The only scenario where using TempData will reliably work is when you are redirecting  This is because a redirect kills the current request  and sends HTTP status code 302 Object Moved to the client   then creates a new request on the server to serve the redirected view   It requires typecasting for complex data type and check for null values to avoid error   public ActionResult Index           var model   new Review                  Body    Start           Rating 5                TempData  ModelName     model          return RedirectToAction  About           public ActionResult About                  var model  TempData  ModelName          return View model

User · Answer

Also the scope is different between viewbag and temptdata  viewbag is based on first view  not shared between action methods  but temptdata can be shared between an action method and just one another

User · Answer

1 TempData    Allows you to store data that will survive for a redirect  Internally it uses the Session as backing store  after the redirect is made the data is automatically evicted  The pattern is the following   public ActionResult Foo            store something into the tempdata that will be available during a single redirect     TempData  foo      bar           you should always redirect if you store something into TempData to        a controller action that will consume this data     return RedirectToAction  bar       public ActionResult Bar         var foo   TempData  foo                   2 ViewBag  ViewData   Allows you to store data in a controller action that will be used in the corresponding view  This assumes that the action returns a view and doesn t redirect  Lives only during the current request    The pattern is the following   public ActionResult Foo         ViewBag Foo    bar       return View        and in the view    ViewBag Foo   or with ViewData   public ActionResult Foo         ViewData  Foo      bar       return View        and in the view    ViewData  Foo     ViewBag is just a dynamic wrapper around ViewData and exists only in ASP NET MVC 3   This being said  none of those two constructs should ever be used  You should use view models and strongly typed views  So the correct pattern is the following   View model   public class MyViewModel       public string Foo   get  set        Action   public Action Foo         var model   new MyViewModel   Foo    bar         return View model       Strongly typed view    model MyViewModel  Model Foo     After this brief introduction let s answer your question      My requirement is I want to set a value in a controller one  that   controller will redirect to ControllerTwo and Controller2 will render   the View    public class OneController  Controller       public ActionResult Index                 TempData  foo      bar           return RedirectToAction  index    two             public class TwoController  Controller       public ActionResult Index                 var model   new MyViewModel                       Foo   TempData  foo   as string                    return View model             and the corresponding view    Views Two Index cshtml     model MyViewModel  Html DisplayFor x   gt  x Foo      There are drawbacks of using TempData as well  if the user hits F5 on the target page the data will be lost   Personally I don t use TempData neither  It s because internally it uses Session and I disable session in my applications  I prefer a more RESTful way to achieve this  Which is  in the first controller action that performs the redirect store the object in your data store and user the generated unique id when redirecting  Then on the target action use this id to fetch back the initially stored object   public class OneController  Controller       public ActionResult Index                 var id   Repository SaveData  foo            return RedirectToAction  index    two   new   id   id              public class TwoController  Controller       public ActionResult Index string id                var model   new MyViewModel                       Foo   Repository GetData id                     return View model             The view stays the same

User · Answer

ASP NET MVC offers us three options ViewData  ViewBag  and TempData for passing data from controller to view and in next request  ViewData and ViewBag are almost similar and TempData performs additional responsibility  Lets discuss or get key points on those three objects   Similarities between ViewBag  amp  ViewData     Helps to maintain data when you move from controller to view  Used to pass data from controller to corresponding view  Short life means value becomes null when redirection occurs  This is because their goal is to provide a way to communicate between controllers and views  It   s a communication mechanism within the server call    Difference between ViewBag  amp  ViewData    ViewData is a dictionary of objects that is derived from ViewDataDictionary class and accessible using strings as keys  ViewBag is a dynamic property that takes advantage of the new dynamic features in C  4 0  ViewData requires typecasting for complex data type and check for null values to avoid error  ViewBag doesn   t require typecasting for complex data type    ViewBag  amp  ViewData Example   public ActionResult Index         ViewBag Name    Monjurul Habib       return View        public ActionResult Index         ViewData  Name      Monjurul Habib       return View         In View    ViewBag Name   ViewData  Name      TempData   TempData is also a dictionary derived from TempDataDictionary class and stored in short lives session and it is a string key and object value  The difference is that the life cycle of the object  TempData keep the information for the time of an HTTP Request  This mean only from one page to another  This also work with a 302 303 redirection because it   s in the same HTTP Request  Helps to maintain data when you move from one controller to other controller or from one action to other action  In other words when you redirect     TempData    helps to maintain data between those redirects  It internally uses session variables  Temp data use during the current and subsequent request only means it is use when you are sure that next request will be redirecting to next view  It requires typecasting for complex data type and check for null values to avoid error  Generally used to store only one time messages like error messages  validation messages   public ActionResult Index       var model   new Review                                 Body    Start                   Rating 5                    TempData  ModelName     model      return RedirectToAction  About       public ActionResult About         var model  TempData  ModelName        return View model       The last mechanism is the Session which work like the ViewData  like a Dictionary that take a string for key and object for value  This one is stored into the client Cookie and can be used for a much more long time  It also need more verification to never have any confidential information  Regarding ViewData or ViewBag you should use it intelligently for application performance  Because each action goes through the whole life cycle of regular asp net mvc request  You can use ViewData ViewBag in your child action but be careful that you are not using it to populate the unrelated data which can pollute your controller

User · Answer

TempData  Basically it s like a DataReader  once read  data will be lost   Check this Video  Example  public class HomeController   Controller       public ActionResult Index                 ViewBag Message    Welcome to ASP NET MVC            TempData  T      T           return RedirectToAction  About               public ActionResult About                 return RedirectToAction  Test1               public ActionResult Test1                 String str   TempData  T      Output - T         return View              If you pay attention to the above code  RedirectToAction has no impact over the TempData until TempData is read  So  once TempData is read  values will be lost    How can i keep the TempData after reading   Check the output in Action Method Test 1 and Test 2  public class HomeController   Controller       public ActionResult Index                 ViewBag Message    Welcome to ASP NET MVC            TempData  T      T           return RedirectToAction  About               public ActionResult About                 return RedirectToAction  Test1               public ActionResult Test1                 string Str   Convert ToString TempData  T             TempData Keep       Keep TempData         return RedirectToAction  Test2               public ActionResult Test2                 string Str   Convert ToString TempData  T       OutPut - T         return View              If you pay attention to the above code  data is not lost after RedirectToAction as well as after Reading the Data and the reason is  We are using TempData Keep     is that   In this way you can make it persist as long as you wish in other controllers also   ViewBag ViewData  The Data will persist to the corresponding View

User · Answer

void Keep    Calling this method with in the current action ensures that all the items in TempData are not removed at the end of the current request        model MyProject Models EmpModel             Layout      Views Shared  Layout cshtml       ViewBag Title    About       var tempDataEmployeet   TempData  emp   as Employee    need typcasting     TempData Keep       retains all strings values         void Keep string key   Calling this method with in the current action ensures that specific item in TempData is not removed at the end of the current request        model MyProject Models EmpModel             Layout      Views Shared  Layout cshtml       ViewBag Title    About       var tempDataEmployeet   TempData  emp   as Employee    need typcasting     TempData Keep  emp       retains only  emp  string values

User · Answer

TempData in Asp Net MVC is one of the very useful feature  It is used to pass data from current request to subsequent request  In other words if we want to send data from one page to another page while redirection occurs  we can use TempData  but we need to do some consideration in code to achieve this feature in MVC  Because the life of TempData is very short and lies only till the target view is fully loaded  But  we can use Keep   method to persist data in TempData   Read More

User · Answer

TempData  will be always available until first read  once you read it its not available any more can be useful to pass quick message also to view that will be gone after first read  ViewBag Its more useful when passing quickly piece of data to the view  normally you should pass all data to the view through model   but there is cases when you model coming direct from class that is map into database like entity framework in that case you don t what to change you model to pass a new piece of data  you can stick that into the viewbag  ViewData is just indexed version of ViewBag and was used before MVC3

[asp.net-mvc-3] ViewBag, ViewData and TempData

Examples related to asp.net-mvc-3