Question

I have a simple Repeater that contains a checkbox and a Full name per each row.
In addition, I have an “Add Name” button that adds a new full name to the database.

Supposingly user checks a few checkboxes and decides to add another name, I would like to be able to add a new name to the repeater without losing the information in the checkboxes that have been already checked.

I understand some javascript code might do the trick the question is how to approach it?
What do I do?

thanks in advance

p.s.
I’ll be glad to hear any advice, not olny regarding js.

Answer 1

Here is quick solution, not very pretty but get the job done. Hope it will give you some new ideas

Default.aspx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace RepeaterCheckbox
{
    public partial class _Default : System.Web.UI.Page
    {
        [Serializable]
        public class Person
        {
            public int Id { get; set; }
            public string Name { get; set; }
        }

        List<Person> personsFromDatabase
        {
            get { return (List<Person>)ViewState["persons"]; }
            set { ViewState["persons"] = value; }
        }

        //here we will store our person selection state
        Dictionary<int,bool> personSelectionState
        {
            get { return (Dictionary<int, bool>)ViewState["data"]; }
            set { ViewState["data"] = value; }
        }

        protected override void OnLoad(EventArgs e)
        {
            if (!IsPostBack)
            {
                #region Test data
                personsFromDatabase = new List<Person>{
                    new Person { Id = 1, Name = "Paul", },
                    new Person { Id = 2, Name = "Tom", },
                };
                #endregion

                Bind(false);
            }
            base.OnLoad(e);
        }

        void Bind(bool isPostback)
        {
            if (!isPostback)
            {
                //initialize person selection mapping
                personSelectionState = new Dictionary<int, bool>();
                foreach (Person person in personsFromDatabase)
                personSelectionState.Add(person.Id, false);
            }

            //map persons to anonymous type that will help us define necessary values
            rpPersons.DataSource = personsFromDatabase.Select(x => new
            {
                Id = x.Id,
                Name = x.Name,
                //get stored selection state for person
                Selected = personSelectionState[x.Id],
            });
            rpPersons.DataBind();
        }

        protected void btnAddPerson_Click(object sender, EventArgs e)
        {
            //update selection states
            UpdateSelectionStatuses();

            if (!String.IsNullOrEmpty(txbName.Text))
            {
                //add new person
                personsFromDatabase.Add(new Person
                    {
                        Id = personsFromDatabase.Count +1,
                        Name = txbName.Text,
                    });

                //add status mapping for new person so there is no error on postback binding
                personSelectionState.Add(personsFromDatabase.Count, false);

                //Refresh data on page, to see new person
                Bind(true);
            }
        }

        void UpdateSelectionStatuses()
        {
            //loop through all items
            for (int i = 0; i < rpPersons.Items.Count; ++i)
            {
                RepeaterItem repeaterItem = rpPersons.Items[i];

                //find checkbox for item
                var checkbox = (CheckBox)repeaterItem.FindControl("chbSelected");
                if (checkbox != null)
                {
                    //get our custom attribute
                    int id = int.Parse(checkbox.Attributes["personId"]);

                    //update stored checkbox status
                    personSelectionState[id] = checkbox.Checked;
                }
            }
        }

        protected void rpPersons_ItemDataBound(object sender, RepeaterItemEventArgs e)
        {
            if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
            {
                var item = e.Item.DataItem;

                var checkbox = (CheckBox)e.Item.FindControl("chbSelected");
                if (item != null && checkbox != null)
                {
                    //get person id from our helper anonymous type
                    System.Reflection.PropertyInfo[] anonymousTypeProperties = item.GetType().GetProperties();
                    int id = (int)anonymousTypeProperties.Where(x => x.Name == "Id").FirstOrDefault().GetValue(item, null);

                    //set custom attribute on checkbox to map checkbox with person
                    checkbox.Attributes["personId"] = id.ToString();
                }
            }
        }
    }
}

Default.aspx

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="RepeaterCheckbox._Default" %>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
    <form id="form1" runat="server">
        <div>
            <asp:Repeater runat="server" ID="rpPersons" OnItemDataBound="rpPersons_ItemDataBound" >
                <ItemTemplate>
                    <p>
                        <asp:CheckBox ID="chbSelected" runat="server" AutoPostBack="false" Checked='<%# DataBinder.Eval(Container.DataItem, "Selected") %>' />
                        <asp:Label ID="lblName" runat="server" Text='<%# DataBinder.Eval(Container.DataItem, "Name") %>' />
                    </p>
                </ItemTemplate>
            </asp:Repeater>
            <div>
                <asp:TextBox ID="txbName" runat="server" />
                <asp:Button ID="btnAddPerson" runat="server" Text="Add person" OnClick="btnAddPerson_Click" />
            </div>
        </div>
    </form>
</body>
</html>