We are using MVC 3 to build a Web site with dynamic menu options so that users only see menu options (action Links) that they are allowed to see based on group and individual privileges.
How can we add dynamic menu options (links to partial views) at run time?
Do we hard code all the links of all the partial views and turn of the ones that are not required using a visibility option?
Can we add the links dynamically from a database?
Let me clarify.
WE have admins that have access to all menu options like Manage Users, Manage Groups, Manage Suppliers, Manage products and Manage Orders.
We have regular sales staff who only need Manage Supliers and Manage Orders.
So based on this we only need to show the links that say Manage Orders and Manage Supplier. Hence they dynamic nature of the links I am trying to set up.
We have the permissions set up in the DB.
Jawahar
I am not sure I entirely understand what you mean when you say "links to partial views". You never really have a hyperlink to a partial view. The two possibilities I can think of are either you want to know how to embed the partial view conditionally, or you want to have hyperlinks to a controller action which returns the partial views.
In the first case, you can just put the #Html.RenderPartial call inside of an #if (myCondition == true) block. With that, the partial view will only be displayed if the condition passes.
In the second case, you can just always call the controller action. In your controller, only return the PartialView if your condition matches. Otherwise, return null.
I found a way of doing this using Method extension with IPrincipal
public static bool IsAllowed(this IPrincipal p, string menuid) {
if (p.Identity.IsAuthenticated) {
//Code here to verify privillegs against Database
}
return false;
}
This would keep it fairly neat in you Layout.cshtml.
#if (User.IsAllowed("menuchoice1")) {
...
}
#if (User.IsAllowed("menuchoice2")) {
<a href="#Url.Action(...)>...</a>
}
Hope this help others looking for similar options
Related
I'm new with ASP.Net Core (3.0 in this case) and I´m trying to create a menu that is visible on all views of a WebApplication, is created dynamically and must be populated only once. Below i explain the steps and try outs i did to reach the goal needed (if required i can share the code I'm using).
This is what i did:
In a simple way, using the "_Layout.cshtml" page, i created a static HTML menu and made all other views simply inherit that layout. So far, so good;
Next challenge comes from the fact that the menu items are dynamically created after a User has logged-in, which i managed to overcome by setting a ModelView inside a controller (HomeController.cs with Index action in this case), and then delivering it to the view. For this case works OK, because the default page is ~\Home\Index\, problem is when i change to a different view with a different controller, the menu has to be rendered again, and so i have to replicate the code (a problem dealt create a BaseController and BaseModel based on this post along side the OnActionExecuted to host the menu generating code)
Now, the biggest problem is the fact that i can only populate the menu once, after the user logs-in. Each time there is a redirect between different controllers/views (post-back of same controller/view works fine), the model is null inside the OnActionExecuted, I tried using ViewData, ViewBag, TemData, but all are null.
So, my question is, how to keep that specific data alive and shared, basically across all the views, and only gets populated once (after each user login) between redirects from different views?
I have been reading around and found several solutions besides the one i did, but i did not found any that could keep data alive throughout the user session the way I need:
ViewBag, ViewData and TempData
Can the shared layout view have a controller in ASP.NET MVC?
Pass data to layout that are common to all pages
To sum up, my flow at this moment, is like this:
User Logged-in
Redirect to default: ~\Home\Index
MenuModelView.cs for the menu gets built and HomeController.cs returns to Index.cshtml with the model attached to it.
Index.cshtml receives the populated ModelView and it uses _Layout.cshtml
The _Layout.cshtml builds the HTML tags for the menu based on the MenuModelView.cs data
User navigates to a different view and steps 3 to 5 are repeated from a specific controller/view
If you want to create a control that can be accessible in all pages without changing every controller, I strongly suggest creating a view component. For a view component has no relationship with your controller, but can access dependencies like database and full HTTP context.
For example, you want to build a custom nav menu, you can just create a view component named NavHeader
using Microsoft.AspNetCore.Mvc;
namespace YourProject.Views.Shared.Components.NavHeader
{
public class NavHeader : ViewComponent
{
public NavHeader(YourDbContext context)
{
// you can access your dependencies, like database.
}
public IViewComponentResult Invoke()
{
// your own logic. You can access HTTPContext here.
var model = new YourOwnModel();
return View(model);
}
}
}
And just call it in any view or layout.
<!DOCTYPE html>
<html>
<head>
<title>Example</title>
</head>
<body>
#*Render your component like this*#
<vc:nav-header></vc:nav-header>
</body>
For more details about view component, please reference:
https://learn.microsoft.com/en-us/aspnet/core/mvc/views/view-components?view=aspnetcore-3.1
https://anduin.aiursoft.com/post/2020/1/4/share-view-component-between-different-aspnet-core-web-project
I'm still learning Laravel and I'm working on a small project to help me understand better. In the project, I am in need of a global array, so that I may display it or its attributes on every view rendered. sort of on a notification bar, so that each page the user visits, he/she can see the number of notifications (which have been fetched in the background and are stored in the array).
I have done some research, and realized that I have to fetch and compile the array in a view composer I think. But everywhere I go, I cant seem to understand how to make a view composer.
I need to fetch the relevant rows from the database table, and make the resulting array available to each view rendered (I'm thinking attaching it somehow to my layouts/default.blade.php file.). Please help, any and all advice is greatly appreciated:)
You can now inject services on your view
More info here: https://laracasts.com/series/whats-new-in-laravel-5-1/episodes/2
You have to use Sub-Views of laravel blade. I guess your functionality is like a sidebar or like a top bar which will be rendered at every page.
//Your Controller pass data
class YOUR_CONTROLLER extends Controller {
public function index()
{
$data = YOUR_DATA;
return view('YOUR_VIEW_FILE', get_defined_vars());
}
}
//In Your View File
#extends('LAYOUTS_FILE')
#section('YOUR_SECTION')
#include('YOUR_SUB_VIEW_FOR_NOTIFICATION')//You need not pass any data passed all data will be available to this sub view.
#endsection
In your sub view
//Do what ever you want looping logic rendering HTML etc.
//In your layout file just yield or render the section that's it
#yield('YOUR_SECTION')
More explanation can be found Including Sub-Views
I have two screens, a standard user screen and an admin screen. The changes between the two are fairly minor - a few extra buttons and options on the admin screen.
As far as MVC best practices, is it better to:
Use the same view and the same viewmodel for both the admin and the standard user screen. That way there is no code duplication, but I will have several if...else statements in the view and controller
Use separate views and viewmodels for the admin and user screens. This leads to some code duplication, but is ultimately the most flexible if the screens end up diverging more than they currently are.
Some other great solution for this?
I would use seperate viewmodels and apply inheritance to your ViewModel .So you are not duplicating the code.
public class CustomerCreateViewModel
{
//Here i i have properties common to both user and admin
public string FirstName { set;get;}
public string LastName { set;get;}
}
public class AdminCustomerCreateViewModel : CustomerCreateViewModel
{
//This property is only for admin
public string ReasonForFiring { set;get;}
}
I personally prefer to keep separate views because it makes things clean and more readable /maintainable. Now you have 2 separate ViewModels, so have separate views. You may consider render Partial Views (in both the views) as necessary
This is really only a question you can answer. You basically said it, if the changes are minor, then us a single view and wrap the administrative functions in if statements that check the users role.
However, I would only do that if there are no model changes between the admin and non-admin versions. Once you add additional model items, then I would suggest using seperate models and views.
Is this possible?
I'd had to clutter my route registrations with random actions that I need for specific reasons that don't need any custom constraints or anything.
I want to do something like Admin/Categories/{action} where action can be anything and the controller is CategoryController.
Is this possible?
routes.MapRoute(null, "Admin/Categories/{action}",
new { controller = "Category" });
If you setup an Admin Area, then the categories controller in that area will be accessed via /admin/controller...
Areas, http://msdn.microsoft.com/en-us/library/ee671793.aspx
I'm currently putting together a multi-tenancy web app using MVC 3. At least 30 different Web sites will share a common codebase, and while also sharing similar under-the-hood functionality, they are need to look significantly different. As a consequence I'm using the URL to internally separate out clients, and an overridden Razor view engine (at least in terms of finding the view) to automatically select either a customised view for a given action, or the default view.
To help 'compartmentalise' a complex page, any particular view will make use of several partials, usually rendered as self-contained actions, so that generally a custom view or partial view will only have small HTML differences, helping to minimise any code specific to a client's site.
I hope you followed that background!
So one HTML page might be made up of lots of little smatterings of HTML partial views, which could come from specific folders for the client, or a general-purpose version. I'm hoping to make it easier for our designer to make minor changes to a page by easily seeing where in the folder structure the bit of HTML he wants to change are.
My proposal then is that each partial will be 'bracketed' with HTML comments such as:
{ Content of partial }
Obviously I could put these in manually, but that's just asking for trouble, for typos, for copied and then modified client versions not being updated with the correct URL. It should be possible to get this from some context and inject it, I think.
At the same time, I need to be able to not do this for certain Actions. Eg, a partial might be generating text inside a textarea, say, so the comments wouldn't be appropriate there. On the whole I'm happy to put these comments in unless I specify that it's not appropriate.
For me this suggests an ActionFilter on an Action, which I can apply site wide and then turn off for certain Actions. I'd hope that one of the overridable events would let me ascertain this path, but I can't seem to find anywhere it's stored. Furthermore, OnResultExecuting seems to fire before the Partial has been selected, and OnResultExecuted seems to have already written out the contents of the Partial, so I can't insert the starting comment here. I also can't find any reference to the path of the selected partial.
Just for completeness, it's my intention that this attribute would only write these comments when compiled in Debug mode.
So, does anyone know how I might be able to get the path to the selected View without any kind of hack between FindPartialView and the Attribute? Is my Attribute method the best choice or is there an easier way to do this? Perhaps something's built in already!
Many thanks for your help.
Well, I've never forgotten about wanting this, and always hoped I'd solve it one day, and thankfully I have.
I've overridden the default WebViewPage (I use the Razor engine), and in particular ExecutePageHierarchy to inject the comments:
public abstract class PaladinWebViewPage : PaladinWebViewPage<dynamic>
{
}
public abstract class PaladinWebViewPage<TModel> : WebViewPage<TModel>
{
public bool DisplaySourceCodeComments
{
get { return ((bool?) ViewBag.__DisplaySourceCodeComments) ?? false; }
set { ViewBag.__DisplaySourceCodeComments = value; }
}
public override void ExecutePageHierarchy()
{
base.ExecutePageHierarchy();
// Filters can be used to set and clear this value so we can decide when to show this comment
if (!DisplaySourceCodeComments) return;
var sw = Output as StringWriter;
if (sw == null) return;
var sb = sw.GetStringBuilder();
sb.Insert(0, string.Format("<!-- Start of {0} -->", VirtualPath));
sb.AppendFormat("<!-- End of {0} -->", VirtualPath);
}
VirtualPath tells us the exact file used to build the HTML, so we can inject the filename before and after. This isn't doing anything at the moment, since the default is to not show comments (the "?? false" in DisplaySourceCodeComments).
Also to use this view page you need to edit Views/Web.config and change the pageBaseType to this type.
I want to selectively turn these comments on and off so I've created an ActionFilter:
public class DisplaySourceCodeCommentsAttribute : ActionFilterAttribute
{
private readonly bool _displaceSourceCodeComments;
public DisplaySourceCodeCommentsAttribute(bool displaceSourceCodeComments)
{
_displaceSourceCodeComments = displaceSourceCodeComments;
}
public override void OnActionExecuted(ActionExecutedContext filterContext)
{
base.OnActionExecuted(filterContext);
var viewResult = filterContext.Result as ViewResultBase;
if (viewResult == null) return;
viewResult.ViewBag.__DisplaySourceCodeComments = _displaceSourceCodeComments;
}
}
I'm slightly unhappy that I've had to use the ViewBag here and also separately in the view page override, as they aren't tightly linked, but I can't find a way for the filter to directly interact with the view page, so this is something of a necessary fudge. It does have the benefit that displaying source code for a view or partial also automatically displays it for any child partials until you turn it off again, since the ViewBag is passed down the chain.
With this in place, any action can turn on the source code comments with
[DisplaySourceCodeComments(true)]
or, obviously turn it off again with false
The Attribute checks that the context result is a ViewResultBase, which means just Views and Partials, so Json or Content or redirects aren't affected, which is very handy too.
Finally, I make this action filter a global when running in debug mode so that every view, and partial has the source comment included, by adding the following line to global.asax.cs:
[#]if DEBUG
// When in debug mode include HTML comments showing where a view or partial has come from
GlobalFilters.Filters.Add(new DisplaySourceCodeCommentsAttribute(true));
[#]endif
I'm really happy I've finally got it sorted so I hope this is useful for someone else.