Show a List of Users Allowed to Read an Object

• Mar 19, 2024
• 2 minutes to read

This topic demonstrates how to create an Action to display a list of users whose roles allow reading a specific object.

1. Create a View Controller with PopupWindowShowAction. This Action displays a list of users in a pop-up window.
2. In the CustomizePopupWindowParams event handler, use the GetSecurityStrategy(XafApplication) method to get a Security Strategy instance.
3. Get the ListView’s Object Space and use its CreateListView(Type, Boolean) method to create a new List View for user objects.
4. Use the IObjectSpace.GetObjects<T>() method to get a list of all users.
5. To check if each user has permissions that allow reading a target object, use the CanReadByUser(SecurityStrategy, IPermissionPolicyUser, Type, IObjectSpace, Object, String) method.
6. Customize the List View’s Collection Source and set the CustomizePopupWindowParamsEventArgs.View property to the created List View.

C#

using System;
using System.Collections.Generic;
using DevExpress.Data.Filtering;
using DevExpress.ExpressApp;
using DevExpress.ExpressApp.Actions;
using DevExpress.ExpressApp.Security;
using DevExpress.Persistent.Base;
using DevExpress.Persistent.BaseImpl.PermissionPolicy;
// ...
public class DisplayUsersWithObjectAccessController : ViewController<DetailView> {
    PopupWindowShowAction displayUsersAction;
    public DisplayUsersWithObjectAccessController() : base() {
        displayUsersAction = new PopupWindowShowAction(this, "DisplayUsersWithObjectAccess", PredefinedCategory.View);
        displayUsersAction.ImageName = "Context_Menu_Show_In_Popup";
        displayUsersAction.CustomizePopupWindowParams += DisplayUsersAction_CustomizePopupWindowParams;
    }
    private void DisplayUsersAction_CustomizePopupWindowParams(object sender, CustomizePopupWindowParamsEventArgs e) {
        Type userType = typeof(ApplicationUser);
        ListView listView = Application.CreateListView(userType, true);
        SecurityStrategy securityStrategy = Application.GetSecurityStrategy();
        List<ApplicationUser> users = new List<ApplicationUser>();
        IObjectSpace objectSpace = listView.ObjectSpace;
        foreach (ApplicationUser user in objectSpace.GetObjects<ApplicationUser>()) {
            if (securityStrategy.CanReadByUser(user, 
                    View.ObjectTypeInfo.Type, 
                    View.ObjectSpace, 
                    View.ObjectSpace.GetKeyValue(View.CurrentObject))) {
                        users.Add(user);
                    }
        }
        listView.CollectionSource.Criteria["UsersWithObjectAccess"] = new InOperator(objectSpace.GetKeyPropertyName(userType), users);
        e.View = listView;
    }
}

The following image shows the result:

Note

Refer to the following help topic to see other methods to check a user’s or role’s permissions: Determine if the Current User Has Specific Permissions.