• Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 1854
  • Last Modified:

mvc textbox add value to listbox

does anyone have example not on the client side but in the controller and model to add a value from a text box to a listbox.
0
Seven price
Asked:
Seven price
  • 4
  • 2
1 Solution
 
käµfm³d 👽Commented:
Within the controller there are no list boxes or text boxes. You only have what was passed to the controller and what you put in the model. You basically need to create a list of items that your model will contain, and then append the incoming value to the model's list. Then spit that list out in the view.

e.g.

Controller
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;

namespace _28167867.Controllers
{
    public class HomeController : Controller
    {
        public ActionResult Index()
        {
            ViewBag.Message = "Modify this template to jump-start your ASP.NET MVC application.";

            return View(new YourModel());
        }

        [HttpPost]
        public ActionResult Index(string textBoxValue, List<string> listBoxValues)
        {
            YourModel model = new YourModel();

            if (listBoxValues == null) listBoxValues = new List<string>();

            listBoxValues.Add(textBoxValue);

            model.TextBoxValue = textBoxValue;
            model.ListBoxValues = listBoxValues;

            return View(model);
        }
    }

    public class YourModel
    {
        public YourModel()
        {
            this.TextBoxValue = string.Empty;
            this.ListBoxValues = new List<string>();
        }

        public string TextBoxValue { get; set; }
        public List<string> ListBoxValues { get; set; }
    }
}

Open in new window


View
@model _28167867.Controllers.YourModel

@{
    ViewBag.Title = "Home Page";
}
@{Html.BeginForm();}
<label for="textBoxValue">TextBox Value:</label>
<input type="text" name="textBoxValue" value="@Model.TextBoxValue" />
<label for="listBoxValues">ListBox Values:</label>
<select name="listBoxValues" multiple="multiple">
@foreach (var item in Model.ListBoxValues)
{
    <option>@item</option>
}
</select>
<input type="submit" value="Submit" />
@{Html.EndForm();}

Open in new window


Be mindful that in the above only the selected values of a <select> list are transmitted back to the server. If you need to persist the entire list, then you will need to do so on the server, and repopulate your model each time in addition to adding the new element.
0
 
Seven priceFull StackAuthor Commented:
error (Object reference not set to an instance of an object.)
<option>@item</option>
}
0
 
Seven priceFull StackAuthor Commented:
ok I tested yours in a totally separate app. But It does not append each every time I try to add another value the last value in the list box diss-appear. This is why we should do it on the client side then add it . correct me if I am wrong.
0
Cloud Class® Course: CompTIA Healthcare IT Tech

This course will help prep you to earn the CompTIA Healthcare IT Technician certification showing that you have the knowledge and skills needed to succeed in installing, managing, and troubleshooting IT systems in medical and clinical settings.

 
käµfm³d 👽Commented:
But It does not append each every time I try to add another value the last value in the list box diss-appear.

Hence my comment above:

Be mindful that in the above only the selected values of a <select> list are transmitted back to the server. If you need to persist the entire list, then you will need to do so on the server, and repopulate your model each time in addition to adding the new element.

If you want to keep the same values in the list while adding new ones, then you have to persist the list on the server side. Update the list in code-behind by adding in the new item. Make sure this updated list is persisted on the server. Then spit the updated list out in the view.

Your only other alternative, AFAIK, would be to insert hidden fields into your view that would get posted back to the server on each request.
0
 
Seven priceFull StackAuthor Commented:
I think its fair to say, Add it on the client side using Json data or knockjs. I have entire form besides the textbox and listbox. Posting back to the server is a little to much for each value. I will just add all the values in mem then send it all at once to the server.
0
 
Seven priceFull StackAuthor Commented:
tks for your insight.
0
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

Join & Write a Comment

Featured Post

Cloud Class® Course: Microsoft Exchange Server

The MCTS: Microsoft Exchange Server 2010 certification validates your skills in supporting the maintenance and administration of the Exchange servers in an enterprise environment. Learn everything you need to know with this course.

  • 4
  • 2
Tackle projects and never again get stuck behind a technical roadblock.
Join Now