variable to show/hide link in View of ASP.NET MVC3

Question

Fairly new to MVC3 and I am doing a simple project for testing purposes. So I have encountered a slight problem which I would like your help about.

At the moment I have this code :-

<p>
@if (UserCanCreate)
{
    @Html.ActionLink("Create New", "Create")
}

My question is, how can I populate the boolean value UserCanCreate from my controller? I tried creating a property in the Controller, but the View still does not see this.

Is there maybe a better way to do this?

Thanks for your help

UPDATED with ViewModel

@model IEnumerable<DBName.ViewModels.ProfileData>


@foreach (var item in Model) {
<tr>
    <td>
        @Html.DisplayFor(modelItem => item.UserName)
    </td>
    <td>
        @Html.ActionLink("Details", "Details", new { id=item.FantaTeamID }) |
        @Html.ActionLink("Delete", "Delete", new { id=item.FantaTeamID })
    </td>
</tr>

}

How can I replace this code now? from where to get item.UserName?

Thanks

Sergii Kudriavtsev · Accepted Answer · 2012-01-19 12:10:38Z

4

There are at least two different ways you can do it.

First one (better one) is using a Model to pass data. For that you should create a Model class:

//Model.cs
public class MyModel
{
    public bool UserCanCreate { get; set;}
}

and specify it at the beginning of your View (use typed view):

@model %Your_model_namespace%.MyModel

...

<p>
@if (Model.UserCanCreate)
{
    @Html.ActionLink("Create New", "Create")
}

And, of course, in your controller action do the following:

public ActionResult YourAction()
{
    ...
    MyModel model = new MyModel();
    model.UserCanCreate = ... ; // Determine if link shall be visible here
    ...
    return View(model);
}

Second (faster one, although not recommended): use ViewData collection to pass values.

For example, in your controller action do:

public ActionResult YourAction()
{
    ...
    ViewData["UserCanCreate"] = ... ; // Determine if link shall be visible here
    ...
    return View();
}

and your view will look like:

...

<p>
@if ((bool)ViewData["UserCanCreate"])
{
    @Html.ActionLink("Create New", "Create")
}

Also important: if you're trying to secure some actions that way then do not forget to add some checks for permissions inside "Create" action code - otherwise any user will be able to execute it by just entering corresponding URL in browser address bar - even if the ActionLink is not present.

UPDATE

As for your comment - you seem to be mixing domain models with view models. Domain models are the ones that represent your database entities, while view models are the ones that should be used for presentation. Generally it's controller's job to convert objects from domain to view models and vice versa.

In your case EF models are domain models.

For ViewModel you should create a separate class which will aggregate your domain model instance and any additional properties you want - like UserCanCreate.

Example model class:

public class UsersViewModel
{
    public IEnumerable<DBName.Models.Users> Users { get; set; }
    public bool UserCanCreate { get; set; }
    ... // Any other additional properties you may require
}

In your controller it will be:

public ActionResult YourAction()
{
    ...
    UsersViewModel model = new UsersViewModel();
    model.Users = ... ; // Get your IEnumerable<DBName.Models.Users> collection from DB and assign it to model property here
    model.UserCanCreate = ... ; // Determine if link shall be visible here
    ...
    return View(model);
}

and in view:

@model %Your_model_namespace%.UsersViewModel

... // use Model.Users wherever you need your IEnumerable<DBName.Models.Users>

<p>
@if (Model.UserCanCreate)
{
    @Html.ActionLink("Create New", "Create")
}

edited Jan 19, 2012 at 12:10

answered Jan 19, 2012 at 11:52

Sergii Kudriavtsev

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5 Comments

JMon Over a year ago

Hi Sergey, I am not using Code First, so what I did was create a model from the Database through EF, so I have all the models gathered together. My Page is using @model IEnumerable<DBName.Models.Users>, which is in DBNameModel.Designer.cs. Can I create a Model class that inherits from this?

Sergii Kudriavtsev Over a year ago

You seems to be mixing domain models with view models. I will update my answer in a moment.

JMon Over a year ago

Hi Sergey, EXCELLENT explanation, thanks a lot! However the loop to display the data is not working now, you can see in my UPDATE question

Sergii Kudriavtsev Over a year ago

If you have done the same way as I suggested then you should replace @foreach (var item in Model) { ... with something like @foreach (var item in Model.Users) { ...

JMon Over a year ago

EXCELLENT! I had IEnumerable<> which was wrong. THANKS A LOT Sergey for your help, all seems more simple now :)

andre · Accepted Answer · 2012-01-19 11:50:41Z

0

When you create the model, set the value

UserCanCreate = _permissionService.Authorize(StandardPermissionProvider.AccessAdminPanel),

answered Jan 19, 2012 at 11:50

andre

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Comments

Serghei Grajdean · Accepted Answer · 2012-01-19 11:58:41Z

0

Your View should interact with Controller using Model. So you should create a strongly typed View and pass to it a Model instance. For example:

// ViewModel
public class MyViewModel
{
     public bool UserCanCreate{get;set;}
}

// Controller
public class MyController : Controller
{
     public ActionResult Index()
     {
          var model = new MyViewModel
          {
              UserCanCreate = _permissionService.Authorize(StandardPermissionProvider.AccessAdminPanel)
          };
          return View(model);
     }

     // Other Actions goes here....
}

// View
<p>
@if (Model.UserCanCreate)
{
    @Html.ActionLink("Create New", "Create")
}

answered Jan 19, 2012 at 11:58

Serghei Grajdean

3802 silver badges7 bronze badges

Comments

Be.St. · Accepted Answer · 2012-01-19 11:59:59Z

0

Your view must have a Model, for example UserModel.

Add UserCanCreate boolean property to UserModel and then you're able to access it in view.

For example:

namespace MvcApplication1.Models
{
    public class UserModel
    {
        public bool UserCanCreate { get; set; }
    }
}

and use it in the view:

@model MvcApplication1.Models.UserModel

@{
    Layout = null;
}

<!DOCTYPE html>

<html>
<head>
    <title>Index</title>
</head>
<body>
    <div>
        @Model.UserCanCreate
    </div>
</body>
</html>

edited Jan 19, 2012 at 11:59

answered Jan 19, 2012 at 11:48

Be.St.

4,1813 gold badges28 silver badges36 bronze badges

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