I am new to mvc and I load ViewBag in a method of controller as,
HomeController: Controller
{
Public ActionResult Index()
{
loadViewBag();
return View();
}
public void loadViewBag()
{
ViewBag.aaa = "something";
}
}
It works fine.
What is my problem is, Now I want to call loadViewBag() method form another controller( say Account) so that I can reuse same method and need to make loadViewBag() method static due to some static variables as:
public static void loadViewBag()
If I make loadViewBag method static, there appear error on ViewBag " An object reference is required for the non-static field, method, or property 'System.Web.Mvc.ControllerBase.ViewBag.get' ".
Is there any solution/suggestion.
Thank You.
Just make it an extension method of ControllerBase e.g.
public static void ControllerExt
{
public static void LoadViewBag(this ControllerBase controller)
{
controller.ViewBag.aaa = "something";
...
}
}
That way you can use it in any controller
public class HomeController : Controller
{
public ActionResult Index()
{
this.LoadViewBag();
return View();
}
}
public class AccountController : Controller
{
public ActionResult Index()
{
this.LoadViewBag();
return View();
}
}
If its only specific to some controllers then it would be more flexible to pass the ViewBag property in e.g.
public static class ControllerHelper
{
public static void LoadViewBag(dynamic viewBag)
{
viewBag.aaa = "something";
}
}
public class HomeController : Controller
{
public ActionResult Index()
{
ControllerHelper.LoadViewBag(ViewBag);
return View();
}
}
ViewBag is a property of your controller (more specifically of ControllerBase), and since a static method has no knowledge of a class instance, you can't access it.
You could pass the controller instance to the method if you want to use a static method or even make it an extension method, but depending on your problem, this solution could be sub-optimal. You may be able to get a better answer if you add more details to your question.
Public ActionResult Index()
{
this.loadViewBag();
return View();
}
public static void loadViewBag(this ControllerBase target)
{
target.ViewBag.aaa = "something";
}
Do you need that to allow different controllers/views to use some common properties?
Then I'd rather recommend a common base controller, while also wrapping ViewBag code into type safe properties (to let the compiler control the data consistency - as you know, ViewBag is not type safe, so any typos and data mismatches won't be noticed until the code gets executed).
1. Introduce a common controller with those wrapper properties
public abstract class MyBaseController : Controller
{
internal long CurrentUserId
{
get { return ViewBag.CurrentUserId; }
set { ViewBag.CurrentUserId = value; }
}
internal Role CurrentUserRole
{
get { return ViewBag.CurrentUserRole; }
set { ViewBag.CurrentUserRole = value; }
}
...
}
Thus, your inherited controllers could simply set the properties - or, with lots of common code just introduce a method in your base controller - similar to what you already have.
2. Introduce a common view class with those wrapper properties
public abstract class MyBaseViewPage<T> : WebViewPage<T>
{
public string Title
{
get { return (string)ViewBag.Title; }
set { ViewBag.Title = value; }
}
public long CurrentUserId
{
get { return (long)ViewBag.CurrentUserId; }
}
public Role CurrentUserRole
{
get { return ViewBag.CurrentUserRole; }
}
}
public abstract class MyBaseViewPage : MyBaseViewPage<dynamic>
{
}
and update web.config to let MVC know you're using a custom base view:
<configuration>
...
<system.web.webPages.razor>
...
<pages pageBaseType="MyRootNamespace.Views.MyBaseViewPage">
...
</pages>
</system.web.webPages.razor>
Now you can use them as normal properties in your controllers and views.
Related
I have the following base class for all controllers-
public abstract class BaseController:Controller
{
public string BaseUrl
{
get { return "something"; }
}
}
I also have the following action filter attribute-
public class CheckQueryStringAttribute : ActionFilterAttribute
{
string baseUrl;
public CheckQueryStringAttribute(string BaseUrl)
{
baseUrl = BaseUrl;
}
}
I would like to use BaseUrl from base controller into attribute as follows-
public class LoginController : BaseController
{
[CheckQueryString(BaseUrl)]
public ActionResult LoginSuccess()
{
return View();
}
}
Is there any way to do it?
You couldn't pass a variable or object reference in attribute constructor parameter because attributes will resolve at compile time so you can only pass constant by their constructor.
But if you exactly explain what you want to do may i can solve your problem in other way.
I have a block of code which is use in pretty much every controller, so I am wondering how, or what's the best practice for reusing code in multiple controllers
Simple example would be this
public String CoolCode(){
// Stuff
return MyStuff;
}
Then in another controller I just use
string something = CoolCode();
Where should I put it, and how to use it in every controller?
Personally I would inject the helper class into the controller:
public interface IHelper
{
string CoolCode();
}
public class Helper : IHelper
{
public string CoolCode()
{
return "Cool code";
}
}
public class SomeController
{
private IHelper _helper;
public SomeController(IHelper helper)
{
_helper = helper;
}
public ActionResult Index()
{
//call _helper.CoolCode();
}
}
Then you would need to inject this using some sort of IoC container, I recommend Castle Windsor
This is all quite abstract but I recommend you read up on it:
http://www.codeproject.com/Articles/560798/ASP-NET-MVC-Controller-Dependency-Injection-for-Be
What you should do is extend the Controller class that all your controllers inherit now and use this abstraction to wrap all of your controllers that use that code:
public class MyControllerBase : Controller
{
public string CoolCode() { ... }
}
now you simply inherit your abstraction rather than the default one:
public class AnyController : MyControllerBase
{
...
}
However depending on what you need precisely different approaches might be more appropriate.
public interface IBaseUserController
{
string SomePropety { get; set; }
ActionResult SignUp(string code, [Form] SomeViewModel model);
}
public class BaseUserController : Controller, IBaseUserController
{
private static string _somePropety = "";
public BaseUserController(){}
public string SomePropety
{
get
{
return _somePropety;
}
set { _somePropety = value; }
}
public virtual ActionResult SignUp(string code, [Form] SomeViewModel model)
{
// ... CoolCode maybe use SomePropety
return View(model);
}
}
public class TestUserController : BaseUserController
{
public TestUserController()
{
SomePropety = "Value";
}
public override ActionResult SignUp(string code, [Form] SomeViewModel model)
{
return base.SignUp(code, model);
}
public ActionResult SignUp2(string code, [Form] SomeViewModel model)
{
return base.SignUp(code, model);
}
}
MVC controller are same as normal class and controller have the same extension .cs
So use can use static method like following.
HomeController objHomeController = new HomeController();
string something= objHomeController.CoolCode();
Here's my scenario:
I've successfully created a custom IIdentity that I pass to a GenericPrincipal. When I access that IIdentity in my controller I have to cast the IIdentity in order to use the custom properties. example:
public ActionResult Test()
{
MyCustomIdentity identity = (MyCustomIdentity)User.Identity;
int userID = identity.UserID;
...etc...
}
Since I need to do this casting for nearly every action I would like to wrap this functionality in an ActionFilterAttribute. I can't do it in the controller's constructor because the context isn't initialized yet. My thought would be to have the ActionFilterAttribute populate a private property on the controller that I can use in each action method. example:
public class TestController : Controller
{
private MyCustomIdentity identity;
[CastCustomIdentity]
public ActionResult()
{
int userID = identity.UserID;
...etc...
}
}
Question: Is this possible and how? Is there a better solution? I've racked my brain trying to figure out how to pass public properties that are populated in an attribute to the controller and I can't get it.
All you have to do is access the ActionExecutingContext of an overloaded OnActionExecuting() method and make identity public instead of private so your actionfilter can access it.
public class CastCustomIdentity : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
((TestController) filterContext.Controller).Identity = (MyCustomIdentity)filterContext.HttpContext.User;
base.OnActionExecuting(filterContext);
}
}
This could be even easier by using a custom base controller class that all of your controllers would inherit from:
public class MyCustomController
{
protected MyCustomIdentity Identity { get{ return (MyCustomIdentity)User.Identity; } }
}
and then:
public class TestController : MyCustomController
{
public ActionResult()
{
int userID = Identity.UserId
...etc...
}
}
You could use a custom model binder...
I can't remember why I used this method over the base controller method #jfar mentions (which is also a good option), but it works well for me and I actually kinda like it because my actions are more self describing through their parameters.
MyCustomIdentityModelBinder.cs
public class MyCustomIdentityModelBinder : IModelBinder
{
public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
{
if (bindingContext.Model != null)
throw new InvalidOperationException("Cannot update instances");
//If the user isn't logged in, return null
if (!controllerContext.HttpContext.User.Identity.IsAuthenticated)
return null;
return controllerContext.HttpContext.User as MyCustomIdentity;
}
}
Inside your application start event in Global.asax.cs
System.Web.Mvc.ModelBinders.Binders.Add(typeof(MyCustomIdentity), new MyCustomIdentityModelBinder());
Then whenever you have a type of MyCustomIdentity as an action parameter, it'll automatically use the MyCustomIdentityModelBinder.
Eg.
public class TestController : Controller
{
public ActionResult Index(MyCustomIdentity identity)
{
int userID = identity.UserID;
...etc...
}
}
HTHs,
Charles
In asp.net MVC, dependency injection with controllers is simple and straightforward. Now, I'd like to remove most of the logic from views by using helpers. The problem is that these helpers use some of the objects that are injected.
Let me write an example:
public interface ISessionData
{
List<string> IdList {get;}
}
public MyController : Controller
{
public MyController(ISessionData sessionData)
{
...
}
}
session data is injected into controller. So far so good. But now I have a helper. Let's say it looks like this:
public class MyHelper
{
private readonly ISessionData sessionData;
public MyHelper(ISessionData sessionData)
{
this.sessionData = sessionData;
}
public bool CheckSomethingExistsInSession(string id)
{
return sessionData.IdList.Any(x => x.Id.Equals(id));
}
}
Now what? I'd like MyHelper to be injected into view. Only way I can see is adding this helper to model and passing it to view every time. Any other ideas?
In MVC it is better to pass ISessionData data from Controller to View (using ViewModel or ViewData):
ViewData["Session"] = sessionData.IdList.ToList();
And remove ISessionData dependency from the helper. Something like this:
public class MyHelper
{
//private readonly ISessionData sessionData;
public MyHelper(/*ISessionData sessionData*/)
{
//this.sessionData = sessionData;
}
public bool CheckSomethingExistsInSession(string id, IList<...> sessionData)
{
return sessionData.Any(x => x.Id.Equals(id));
}
}
In View:
<% var somethingExists = new MyHelper().CheckSomethingExistsInSession(
1, ViewData["Session"] as IList<...>); %>
UPDATED:
public static class MyHelper
{
public static bool CheckSomethingExistsInSession(string id, IList<...> sessionData)
{
return sessionData.Any(x => x.Id.Equals(id));
}
}
<% var somethingExists = MyHelper.CheckSomethingExistsInSession(
1, ViewData["Session"] as IList<...>); %>
You should remove session logic from your controller's constructor and insert it into the controllers action method by using an IModelBinder. See below:
public class SessionDataModelBinder : IModelBinder
{
public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
{
// Get/create session data implementating ISeesionData or whatever here. This will be return to the controller action method.
return new SessionData()
}
}
On you controller you would do something like:
public MyController : Controller
{
public MyController()
{
....
}
public ActionResult Index(ISessionData sessionData)
{
// do stuff with ISessionData.
// Redirect or whatever.
return this.RedirectToAction("Index");
}
}
You need to add your IModelBinder like below for it to be called. You can do this in the http application's startup.
System.Web.Mvc.ModelBinders.Binders[typeof(ISessionData)] = new SessionDataModelBinder();
Is it possible to inherit from both ViewPage and ViewPage<T>?? Or do I have to implement both. Currently this is what I have for ViewPage. Do i need to repeat myself and do the same for ViewPage<T>??
public class BaseViewPage : ViewPage
{
public bool LoggedIn
{
get
{
if (ViewContext.Controller is BaseController)
return ((BaseController)ViewContext.Controller).LoggedOn;
else
return false;
}
}
}
Create both versions:
public class BaseViewPage : ViewPage
{
// put your custom code here
}
public class BaseViewPage<TModel> : BaseViewPage where TModel : class
{
// code borrowed from MVC source
private ViewDataDictionary<TModel> _viewData;
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
public new ViewDataDictionary<TModel> ViewData {
get {
if (_viewData == null) {
SetViewData(new ViewDataDictionary<TModel>());
}
return _viewData;
}
set {
SetViewData(value);
}
}
protected override void SetViewData(ViewDataDictionary viewData) {
_viewData = new ViewDataDictionary<TModel>(viewData);
base.SetViewData(_viewData);
}
}
then
public class MyCustomView : BaseViewPage
{
}
or
public class MyCustomView : BaseViewPage<MyCustomViewData>
{
}
Depending on how you are doing things you might want to look at
ViewContext.HttpContext.Request.IsAuthenticated
it might save you some time instead of extending the ViewPage class.
If there is some other data that you are after you could maybe write an extension method to one of the classes that provides the data. E.g. if LoggedIn was stored in the session you could extend the context to give you an IsLoggedIn() in method.
Edit:
As your extending a class that is already available in the both the base and strongly typed view it will be available in both. The only other way around is to reimplement the strongly typed version as above.
I wouldn't put this in the View, instead I'd have it as a property on the ViewModel (have a BaseViewModel). It will be easier to test as well as ensuring you're not going down the slope of putting business logic into the views.