How do I check if a ViewBag exists?

How do I check if a ViewBag exists?

1. Check in html what output this line of code @if ((bool)ViewData. ContainsKey(“FormSubmitFlag”) == false) generates. It would give you better Idea what is going wrong.
2. using @ViewBag. Property!=
3. possible duplicate of Checking to see if ViewBag has a property or not, to conditionally inject JavaScript. – Mate.

Why is ViewBag null?

ViewBag only transfers data from controller to view, not visa-versa. ViewBag values will be null if redirection occurs.

What is ViewBag C#?

In simple terms “ViewBag is the data holder that enables the definition of a dynamic property and holds the data that can be passed from a controller to a view”.

Where viewdata is stored in MVC?

The viewbag and viewdata, being properties of the controller, are stored on the heap as reference types are in . net.

What is ViewData in MVC?

ViewData is a dictionary of objects that are stored and retrieved using strings as keys. It is used to transfer data from Controller to View. Since ViewData is a dictionary, it contains key-value pairs where each key must be a string. ViewData only transfers data from controller to view, not vice-versa.

How do you use temp data?

TempData is used to transfer data from view to controller, controller to view, or from one action method to another action method of the same or a different controller. TempData stores the data temporarily and automatically removes it after retrieving a value. TempData is a property in the ControllerBase class.

How do I clear my ViewBag?

ViewData. Clear(); As ViewBag uses it internally.

What is the difference between ViewBag and ViewData in MVC?

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.

Why TempData is used in MVC?

What is TempData and How to Use in MVC? TempData is used to transfer data from the view to the controller, the controller to the view, or from an action method to another action method of the same or a different controller. TempData temporarily saves data and deletes it automatically after a value is recovered.

What is the difference between viewbag and Viewdata?

In general, ViewBag is a way to pass data from the controller to the view. It is a type object and is a dynamic property under the controller base class. Compared to ViewData, it works similarly but is known to be a bit slower and was introduced in ASP.NET MVC 3.0 (ViewData was introduced in MVC 1.0).

How do I use viewbag objects?

You can use ViewBag objects for small amounts of data, transferring it from the controller to the view. It will work well for such cases as: It’s a great way to access data that you use but may reside outside the data model. It is also easy to use because it’s implemented as a property of both controllers and view.

Why doesn’t my code work when I use viewbag?

Your code doesnt work because ViewBag is a dynamic object not a ‘real’ type. Show activity on this post. Instead of using the ViewBag, use ViewData so you can check for the of the item you are storing. The ViewData object is used as Dictionary of objects that you can reference by key, it is not a dynamic as the ViewBag.

What are the limitations of using viewbag?

The use of ViewBag has some limitations in that the compiler cannot check dynamic types and you would need to run your program first to find the errors when you use it. As such, using ViewModel is highly recommended in some instances. For more information, check out the following resources and tutorials: