Accessing params hash in view - ASP.NET MVC3

Question

I want to access a request parameter in (Razor) View. For example, bgColor sets the background color of the page. In View, I need to set Request["bgColor"] ?? "red". In contrast with RubyOnRails, where (in addition to the Request object) we have params hash with each request and that param hash is accessible in controllers as well as the rendered views for that request (params[:bgColor]), what would be the best 'n sleek way to access a request parameter in Razor-View:

Request["paramName"]?
Pushing it to ViewBag.bgColor in controller?
Is there any parameter object/hash (like happen in RoR) which contains all the request params, whether they are captured in action's parameter list or not?

Darin Dimitrov · Accepted Answer · 2012-01-04 09:19:08Z

2

I want to access a request parameter in (Razor) View

In a properly designed ASP.NET MVC application views do not access anything else than the view model that it is passed to it from the controller action. A view should not try to pull data from Requests, Sessions, Cookies, Database, ... A view is there to work with a view model. As far as background colors are concerned, writing a custom HTML helper that will look for some parameter in the request and generate corresponding markup seems like a good solution.

answered Jan 4, 2012 at 9:19

Darin Dimitrov

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6 Comments

vulcan raven Over a year ago

Thank you for elaborating about the convention. We shouldn't access those global objects in View, we can access in helper. If we use the objects in viewmodel, is there a way to map those parameters from viewmodel to their corresponding models OR we need to map them manually when saving the objects?

Darin Dimitrov Over a year ago

@vulcanraven, you could have your controller actions take view model as parameters. The default model binder will take care of automatically instantiating and populating those objects from the request values following standard conventions.

vulcan raven Over a year ago

There is one hiccup in that procedure. We lost decorators of original model when hop through viewmodel. This [Display(Name="First Name in Model")] in StudentModel will be lost when I try to use Student object in a view via some viewmodel. Now,supposedly I need to use several properties of Student in my view,decorating the entire Student object in viewmodel would set the same display name for each property of Student model!if I don't use Student instance rather redefine those properties in viewmodel with corresponding decorators, I'd lost auto-instantiating & populating!

Darin Dimitrov Over a year ago

@vulcanraven, I am not following you. Could you provide some concrete code example of what you are trying to achieve and what doesn't work?

vulcan raven Over a year ago

I have three entities in database with join table as non-PJT or association with payload. Student, StudentFloorJoin and Floor. Student and Floor both have one to many relation with StudentFloorJoin. The FloorViewModel have a MultiSelect studentlist, an instance of Floor and a collection of StudentFloorJoin for payload field (RoomName) against each selected student. The controller code for create and edit method is quite bulky because we need to create the StudentFloorJoins manually for the current floor with selected students and EF doesn't support non-PJT. Is there a better way of doing that?

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