How to obtain list of selected values from Select2 dropdown list and pass to controller?

Question

I am using MVC to build a website. On this current view, admin can select 1+ users and 1 role to assign to the selected users. I am having trouble obtaining the list of selected users. I am using a model to display all the users and their current roles, so there are no properties that save data from the form. Here is the form within the view ManageRoles.cshtml :

@using IssueTracker.Areas.Identity.Data;
@model List

@{
    ViewData["Title"] = "Manage User Roles";
}

@section Scripts2
{
    
    
    
    
    
}

    
        
            
                
                    Change or Update User Roles
                
            
            
                
                    
                        Select 1 or More Users:
                        
                            
                        
                    
                    
                        Select the Role to Assign:
                        
                    
                    
                        
                            
                        
                    
                
            
        
    

    
        
            
                
                    Current Personnel
                
            

            
                
                        @if (Model.Any())
                        {
                            foreach (var user in Model)
                            {
                                
                            }
                        }
                    
                    
                        
                            User
                            Role
                        
                    
                    
                                    @user.userName
                                    @user.roleNames
                                
                    
                        
                            User
                            Role
                        
                    
                
            

        

    


@section Scripts{
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
}

Here is the controller:

using System.Diagnostics;
using Microsoft.AspNetCore.Mvc;
using IssueTracker.Models;
using Microsoft.AspNetCore.Authorization;
using IssueTracker.Areas.Identity.Data;
using Microsoft.AspNetCore.Identity;
using System.Security.Claims;

namespace IssueTracker.Controllers;

[Authorize]
public class HomeController : Controller
{
    private IssueTrackerIdentityDbContext application;
    private UserManager userManager;
    private RoleManager roleManager;

    public HomeController(IssueTrackerIdentityDbContext app, UserManager userManager,
        RoleManager roleManager)
    {
        application = app;
        this.userManager = userManager;
        this.roleManager = roleManager;
    }

    public IActionResult Index()
    {
        return View();
    }

    [Authorize(Roles = "Admin,Demo Admin")]
    public IActionResult ManageRoles()
    {
        var model = new List();

        foreach (var user in userManager.Users)
        {
            var roleList = userManager.GetRolesAsync(user).Result;
            var roles = string.Join(", ", roleList);

            var userRoleViewModel = new UserRoleViewModel
            {
                userName = user.FirstName + " " + user.LastName,
                roleNames = roles
            };

            model.Add(userRoleViewModel);
        }

        return View(model);
    }

    [HttpPost]
    public async Task ManageRoles(List userList, string roleName)
    {
        foreach (string userName in userList)
        {
            ApplicationUser user = await userManager.FindByNameAsync(userName);
            var roles = await userManager.GetRolesAsync(user);
            await userManager.RemoveFromRolesAsync(user, roles.ToArray());
            await userManager.AddToRoleAsync(user, roleName);
        }

        return RedirectToAction("ManageRoles");
    }

    [ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
    public IActionResult Error()
    {
        return View(new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier });
    }
}

and here is the model UserRoleViewModel.cs being used:

using System;
namespace IssueTracker.Models
{
    public class UserRoleViewModel
    {
        public String userName { get; set; }

        public String roleNames { get; set; }
    }
}

I understand that the name property can be used within the form (I used that to successfully obtain the selected role); however, I am not sure how to use that for the select2 list. How can I obtain a list of the selected options and send that to the controller to parse into ApplicationUsers. Thank you!

Dmyto Holota · Accepted Answer

In this case you will need to add a name tag as name='userList' and modify the list parameter in ManageRoles method to List userList.

Any inputs in the form you want to submit need to have a name and it needs to be the same as the param name in you're controller.

And the list change is because when you select a value, the value is an string not the view model.

Hope this helps :)

How to obtain list of selected values from Select2 dropdown list and pass to controller?

Answers (1)

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