I wonder if I could get some ideas on how best to approach this.
I have a Razor Pages application. I have several areas, and each area has its own layout page and menus.
This is pretty straight forward, but I have a couple of pages I need to share with two or more areas. These shared pages will be passed an argument that indicates which area it's being used by, and I would want the layout page (menu) for that page to be the one for that area. (Ideally, the URL would also reflect the current area.)
I'm not sure if this is practical. I'd like to keep things as simple as possible. But all I come up with is some fairly complex routing stuff.
Two options I can think of:
Put the shared page in the root Pages folder and use AddPageRoute to add multiple routes to the shared page including a parameter for the area name:
options.Conventions.AddPageRoute("/SharedPage", "{areaName}/alias1");
options.Conventions.AddPageRoute("/SharedPage", "{areaName}/alias2");
You can set the layout based on the value of RouteData.Values["areaName"]. Don't use area as the parameter name. It's a reserved word as far as routing is concerned:
#{
if(RouteData.Values["areaName"] == "foo")
{
Layout = "_FooLayout";
}
if(RouteData.Values["areaName"] == "bar")
{
Layout = "_BarLayout";
}
}
Add pages to the areas that act as placeholders to generate the routes, and then extract the body of the shared page to a partial that can be placed in the top level Pages/Shared folder so that it is accessible to all other pages in the application. If you want to centralise some of the processing for the shared page, create a class that inherits from PageModel and put your processing logic there, then have the actual PageModel classes inherit from that.
You can make this by using partial views.
So, create one patial view and place it not in areas (in Common for example or other folders).
In areas folder create master view that render only your Partial view.
Related
TL; DR Are "partial Pages" possible in ASP.NET Core 2.0? If so, why am I getting the error described below?
I've been messing with the new Razor Page feature of ASP.NET 2.0 and having some trouble with partials. The documentation linked above refers to "partials" in several places, but only to the extent of saying mystical things like "The layouts, templates, and partials you're using with MVC controllers and conventional Razor views just work." Do they mean partial Views, like what we're used to, or some new kind of partial Page also? They show that files with the conventional Partial suffix in the name can be placed in the Pages/ folder, but the files that they mention (e.g., _ValidationScriptsPartial.cshtml) don't have the #page declaration. If "partial Pages" are indeed a new thing, then I would expect the following minimal scenario to work:
A Page file named Derp.cshtml:
#page
#namespace MyApp.Pages
#model DerpModel
<p>Member 1: #Model.Member1</p>
<p>Member 2: #Model.Member2</p>
A class file named Derp.cshtml.cs in the same directory (nested under the first in VS 2017's Solution Explorer), containing the following class:
namespace MyApp.Pages {
public class DerpModel : PageModel {
public void OnGet() {
Member1 = "Derp Member1";
Member2 = "Derp Member2";
}
public string Member1 { get; set; }
public string Member2 { get; set; }
}
}
A second Page file named DerpWrapper.cshtml in the same directory, with the following code:
#page "{id}"
#namespace MyApp.Pages
#model DerpModel
<p>Outer Member 1: #Model.Member1</p>
<p>Outer Member 2: #Model.Member2</p>
#Html.Partial("Derp", Model)
And of course a _ViewImports file that declares #namespace MyApp.Pages
Note that both Razor Pages have the same #model type, and the second Page basically wraps up the first one with a call to Html.Partial() and passes its Model. This should all be pretty standard stuff, but upon navigating to http://localhost:xxx/DerpWrapper, I get a 500 response due to a NullReferenceException with the following stack trace.
MyApp.Pages.Derp_Page.get_Model()
MyApp.Pages.Derp_Page+<ExecuteAsync>d__0.MoveNext() in Derp.cshtml
+
<p>Inner Member1: #Model.Member1</p>
...
MyApp.Pages.DerpWrapper_Page+<ExecuteAsync>d__0.MoveNext() in DerpWrapper.cshtml
+
#Html.Partial("Derp", Model)
...
Why does the "wrapper" Page's Model equal null? Is there no way to define a Razor Page and display it from another Page or View with Html.Partial()?
Razor’s partial views are basically .cshtml views that are transcluded into another view, that is a razor view or a razor page. They are rendered within that view and as such inherit some of the view’s properties, e.g. its ViewData. They however do not have a controller, a page model or some other kind of “code behind” that gives you a way to run code for the partial.
As such, the primary use for partials is to extract common components that do not contain logic on their own into separate and reusable files.
The other kind of reusable components that exist in Razor are view components. View components are similar to partials but they do have an actual class that backs them and that allows you to add your own logic to the view component.
At the moment, view components follow the MVC layout for views, meaning the view component is actually a class and you return a view from its Invoke method which causes the view engine to locate that .cshtml in the Views folder. David Fowler confirmed to me though, that they are working on a Razor page like experience for view components too, so in a later version of ASP.NET Core, you will eventually be able to write a .cshtml view component and add some code-behind to it (just like Razor pages).
Coming back to your question though, at the moment there are two kinds of entry points for an MVC route: An MVC controller, possibly returning a view, and a Razor page. Neither of these can invoke one or the other inside of them though. If you are rendering a view, you can load partials or view components but not other “full” views or Razor pages. And if you’re rending a Razor page, you also can load partials or view components, but still no other “full” views or Razor pages.
So what you want to do is simply not possible because a Razor page is supposed to be an entry point to the route, and while invoking any view as a partial may work (in some situations), you will certainly neither get the controller for that view nor the page model running for it. If you want to invoke something that has complex logic, you should use view components instead.
Answers on Stack overflow remain for ages so it's important that we ensure that they are improved.
To add onto Poke's Answer or rather to correct it. Partial views separate common sections between pages. These sections can include logic. But that logic should not involve any field(variables, or objects) contained or defined within any specific page. They can apply logic though dependency injection... by injecting them into the partial view.
I'm trying to build a web application which will support multiple organisations. To keep things simple (as I don't have a lot of experience with MVC), I set up the custom routing like site.com/organisation1, site.com/organisation2 etc.
Each organisation has to be able to choose their own colors, fonts and images on their page. The structure of the page and the inner workings of the application will be the same for each organisation.
EDIT: Organisations have to be able to create and style their page on-the-fly. No developer should be involved during this process.
I'm not sure as to what is the best approach to separate the different layouts. Does anyone have a suggestion?
Thanks in advance
Try this:
Have seperate layout for each organisation with specific styles like organisation1_layout.cshtl, org2_layout.cshtml in Views/Shared folder.
2.In _Layout.cshtml, determine organisation using URL/Routing details and set layout accordingly.
#{
Layout = "~/Views/Shared/_Layout.cshtml";
if (Request.Url.ToString().Contains("Organisation1") {
Layout = "~/Views/Shared/Org1.cshtml";
}
else
{
Layout = "~/Views/Shared/Org2.cshtml";
}
}
I'm using the typical built in view engine in mvc3 (is there a proper name for it?) for views and master pages and it's including a Razor partial view on the .aspx page. In the masterpage, there is a ContentPlaceHolder with an ID of "ScriptContent".
I want to be able to fill that ContentPlaceHolder from within the Razor partial view but I don't think this is possible. Does anyone know if it is possible and how I would go about doing that?
I already tried rendering it in the partial like so, but that didn't work.
#section ScriptContent {
... content ...
}
It would be very difficult, so much so that I'd recommend finding another way :(. I wish it was easier, but these are the complexities of integrating a new view engine into an existing legacy system.
To give you a head start if you really want to try it: You'd probably need to create a custom base class inheriting from WebViewPage for your Razor content pages, override some of the methods (honestly I'm not too familiar with that aspect so you'd need to debug to follow the pipeline) so that instead of treating the Layout property as the path to a Layout page, you treat it as a Master page. Then you'd need to instantiate the master page and somehow convert the Sections (which were transformed into calls to DefineSection by the Razor parser, and should be stored in a Dictionary somewhere on the base class) in to Content controls and stuff them in the Master Page.
If I haven't boggled your mind by this point, you may just be able to pull this off, but to be honest, I'd avoid it.
P.S. We refer to the older view engine as "ASPX", based on its file extension ;).
I've developed my own custom users and roles objects using ActiveRecord that do NOT extend the default Asp.Net providers and therefore I can't get the user from the HttpContext. I can create a custom htmlhelper to render menus but should my views render the menu or the master page?
If it's the master page how can I pass to the custom htmlhelper things like current user since some menu items depend on the user roles.
Also, how can I detect what controller is being viewed inside my master pages?
1) If your menu functionality is supposed to exist on multiple pages, then it makes sense to put it in the master page. If not, then the normal view.
2) A popular choice is to make all of your ViewModels inherit from a base view class, and then your Master page uses that. Example:
System.Web.Mvc.ViewMasterPage<ViewBase>
System.Web.Mvc.ViewPage<MyViewModel>
public class MyViewModel : ViewBase { }
3) You can pull out the specific controller from the route data. However, if you need specific functionality for certain controllers, I would just suggest using a different master page for those views than trying to make all of your views use the same master page.
In general, all ASP.NET controls (whether WebForms or MVC) should control their own state.
In the case of handling navigation, I'd say create a .ASCX (partial view) and place it on your master page. Let the partial view control how it is displayed based on the HttpContext.
I'm working on a sort of a CMS/Wiki application to help me experiment with the new Asp.Net MVC framework, and I'm trying to wrap my head around some of the code organization.
Right now, I have three views that cover displaying an article: Index, Edit, and Rename. All three views display the contents of the current page, or placeholder content stating that the page does not exist.
This is currently accomplished with the following code in the action method for each view:
MyPage myPage = null;
if (!string.IsNullOrEmpty(pageName)) {
myPage = mRepository.GetMyPage(pageName);
}
//Page does not exist.
if (myPage != null) {
ViewData["pageContent"] = myPage.GetParsedSource(new PageState());
ViewData["pageSource"] = myPage.Source;
ViewData["title"] = myPage.Title;
}
else {
ViewData["title"] = pageName;
ViewData["pageContent"] = "Page does not exist, feel free to create it!";
ViewData["pageSource"] = "";
}
ViewData["pageName"] = pageName;
My question is, where should this logic actually go?
1) The Controller (as it is now), which requires the above code to be replicated across action methods?
2) The Model, defaulting values for pageSource to the verbiage shown above? This would have the downside of moving display text into the model.
3) The View, using a null coalescing operator to convert null ViewData entries to their defaults?
4) In the Views, but add additional controllers to handle cases where the pageName does not exist.
EDIT:
Hopefully this should clarify things a little. The flow of the application is as follows:
When the user enters a URL (i.e. /pages/page_title), they arrive at a screen which displays the content of the article, along with hyperlinks labeled "edit" and "rename."
Clicking edit displays a page which contains the article content, as well as form controls to edit the article's source.
Clicking rename displays a page which contains the article content, as well as form controls to edit the article's name.
I would have several actions:
Lookup
Display
Create
Edit
Rename
In your default Lookup controller action (which gets hit when the user asks for, say, "/wiki/article-title"), you can redirect (RedirectToAction()) to the appropriate action as necessary. That encapsulates your Create logic into its own controller, and can also be called directly (RESTful). Same with the others. That also allows you to keep your views very, very stupid (always a good thing).
I would keep it in the controller but extract it out so that you don't have to replicate the code in each of the actions.
Maybe set some defaults in the controller's constructor and then have a separate private method (ie. not an action method) that takes your MyPage object and sets the viewdata that is shared between your actions.