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Remove() function seems only removes a couple of controls at a time

I'm trying to remove multiple controls at a time (textboxes and checkboxes) in a windows form application. Basically, I have a row of textboxes and a corresponding checkbox. When the "delete rows" button is clicked, it should remove all rows that have been selected. But it only seems to remove two or three at a time (the same two or three in each row, but there doesn't seem to be any reason it selects those same two or three). I've attached a couple of screenshots showing what is happening.
Here I've selected a couple of rows:
After hitting delete once:
After hitting delete twice:
This just shows the names of each element. As you can see, the names are the same in each row:
Here is the relevant code:
//Gets a list of all ticked checkboxes
public List<string> checkForChecked()
{
var allCheckboxes = tabPage1.GetAllControlsOfType<CheckBox>();
int count = allCheckboxes.Count<CheckBox>();
List<string> checkedChecks = new List<string>();
foreach(Control c in tabPage1.Controls)
{
if(c is CheckBox && ((CheckBox)c).Checked)
{
checkedChecks.Add(c.Name.ToString());
}
}
return checkedChecks;
}
//The button click. Loop through elements and remove ones with the right name
private void button2_Click(object sender, System.EventArgs e)
{
List<string> toDelete = checkForChecked();
foreach (var val in toDelete)
{
foreach (Control item in tabPage1.Controls.OfType<Control>())
{
if (item.Name == val.ToString())
{
tabPage1.Controls.Remove(item);
}
}
}
}
I'm using a windows form app, no asp or other web technology.

It's a common error of removing items from a collection while enumerating it. For example:
foreach (Control c in Controls)
Controls.Remove(c);
will remove only half of the controls and leave every second control.
Some of the common solutions to the general problem are:
removing items in reverse order starting from the end of the collection
removing the first found item until no items found
enumerating a copy of the collection
In your case, both methods can be combined to something like this ( .Find returns Control[] ) :
foreach (var cb in tabPage1.Controls.OfType<CheckBox>())
if (cb.Checked)
foreach (var c in tabPage1.Controls.Find(cb.Name, false))
tabPage1.Controls.Remove(c)

You could try something more like:
private void button2_Click(object sender, EventArgs e)
{
List<CheckBox> CheckedBoxes = new List<CheckBox>();
foreach (CheckBox cb in tabPage1.Controls.OfType<CheckBox>())
{
if (cb.Checked)
{
CheckedBoxes.Add(cb);
}
}
foreach (CheckBox cb in CheckedBoxes)
{
string cbName = cb.Name;
cb.Dispose();
// ... probably more code in here to find the other controls
// ... in the "row" based on "cbName"
}
}

You are iterating the controls collection and removing a control, which effects the index of every item in the collection every time you call the Remove() method. This probably messes with your iterator in the foreach, thus the 'skipping' behavior. When removing from any controls collection it is best not to be iterating it at the same time. Moreover, when looping on a Controls collection where you are removing items, code your loops as iterators working backwards.
for (var i=Parent.Controls.Count-1; i >=0; i--)
{
if (someCondition) Parent.Controls.Remove(Parent.Controls[i]);
}
Here is a bit cleaner version of your code. The list returned from the CheckForChecked method is now a list of controls which is easier to use than a list of the controls names.
In the remove, we are iterating the list of things to delete, not the controls collection from which we are deleting.
//Gets a list of all ticked checkboxes
public List<Control> CheckForChecked()
{
var tabPage1 = new TabPage();
var results = new List<Control>(0);
results.AddRange(from Control c in tabPage1.Controls
where c is CheckBox && (c as CheckBox).Checked
select c);
return results;
}
//The button click. Loop through elements and remove ones with the right name
private void button2_Click(object sender, System.EventArgs e)
{
var toDelete = CheckForChecked();
var tabPage1 = new TabPage();
foreach (var val in toDelete.Where(val => tabPage1.Controls.Contains(val)))
{
tabPage1.Controls.Remove(val);
}
}
Hope this helps someone.

How to get id of the selected item in combobox and populate another combobox with it?

I have 2 comboboxes created with Ajax Toolkit. One of them has a list of systems. I wanted to fill the other combobox with a list of subsystems whenever a system is selected. I did not use DisplayMember or ValueMember and most examples are using them.
.aspx side just in case:
<ajaxToolkit:ComboBox ID="cbox1" runat="server" OnSelectedIndexChanged="cbox1_SelectedIndexChanged" />
Is this doable with what I'm trying? Is the event I used correct for the situation?(I guess not,but other events seem to be unrelated) Let me show you the code:
protected void fillSystemCombo()
{
var sysOperations = new ModelOperations.ConstantSystem.ConstantSystemOperations();
var sys = sysOperations.GetSystemList().TransactionResultList;
foreach (var item in sys)
{
cbox1.Items.Add(item.description);
}
}
This works fine and I can see the systems in my first combobox.
This is what I tried for populating the second one:
protected void cbox1_SelectedIndexChanged(object sender, EventArgs e)
{
var subSysOperations = new ModelOperations.ConstantSubSystem.ConstantSubSystemOperations();
int index = Convert.ToInt32(cbox1.SelectedItem.Value);//i think this should get the id...
var subsys = subSysOperations.GetSubSystemList().TransactionResultList;
foreach (var item in subsys)
{
if (item.sysID == index)
{
cbox2.Items.Add(item.description);
}
}
}
sysID is the foreign key in SubSystem which is the ID of System. By the way, my SelectedIndexChanged event never fired when I was debugging the program even though I clicked on an item in combobox.

I've actually found the answer after carefully reading the parameters taken by Items.Add. It wants a ListItemso if I create a ListItem inside the loop I can finally add my items with both a Text and a Value like this:
foreach (var item in sys)
{
combo1.Items.Add(new ListItem { Text = item.description, Value = item.ID.ToString() });
}
After that I can get the index with
int index = Convert.ToInt32(combo1.SelectedValue);

How to deselect a single Item in a listbox

I have a listbox on my asp page, and I was wondering if there was anyway in code behind or javascript to deselect a selected item in my listbox. the selection mode is single.
Any help please? I tried adding a handler on selectedindexchanged...but it doesn't hit it if I am clicking on the same selectedItem.

I fixed my issue as Andrew pointed out, by setting the SelectedIndex = -1;
But, this created weird behavior since now I would have A checkboxList being populated from the selected list item I chose, and there was no Idea to see which list item populated it after wards.
So What I did was added 2 more lines of code on top of what andrew suggested and it worked great.
var index = lstGroups.SelectedIndex;
lstGroups.SelectedIndex = -1;
lstGroups.Items[index].Attributes["style"] = "background-color:lightblue";
Thanks for pushing me in the right direction!

You can use the following workaround if your SelectionMode="Single" and you want to deselect an item on second click.
Create a property in your page to keep the last selected list item value using session. I am assuming the selected value in your listbox is always int
public int ListBoxLastSelected
{
get
{
if (Session["ListBoxLastSelected"] != null)
return Convert.ToInt32(Session["ListBoxLastSelected"]);
return -1;
}
set { Session["ListBoxLastSelected"] = value; }
}
Create the following method
private void EnableListboxDeselect()
{
if (!IsPostBack)
{
// Register a postback event whenever you click on the list item
ClientScriptManager cs = Page.ClientScript;
lstMyList.Attributes.Add("onclick", cs.GetPostBackEventReference(lstMyList, "clientClick"));
Session["ListBoxLastSelected"] = null;
}
if (IsPostBack)
{
// Ensure the postback is from js side
if (Request["__EVENTARGUMENT"] != null && Request["__EVENTARGUMENT"] == "clientClick")
{
if (CorpListLastSelected == Convert.ToInt32(lstMyList.SelectedValue))
{
lstMyList.ClearSelection();
CorpListLastSelected = -1;
}
else
{
ListBoxLastSelected= Convert.ToInt32(lstMyList.SelectedValue);
}
}
}
}
On your Page_Load add the below code
protected void Page_Load(object sender, EventArgs e)
{
EnableListboxDeselect();
}

Getting the selected values in a checkbox list

I have set up the following method when the checkbox list is checked.
protected void chk1_SelectedIndexChanged(object sender, EventArgs e)
{
foreach (ListItem list in chk1.Items)
{
if (list.Selected)
{
string name = list.Value.ToString();
}
}
}
I need to display the checked item from the checkbox list. However, for each iteration the selected attribute always comes false. It never satisfies the condition
if (list.Selected)
{
string name = list.Value.ToString();
}
How do I fix this?

Try something like this
var selectedListItems = chk1.Items.Cast<ListItem>().Where(x => x.Selected);
or in your case
var list = chk1.Items.Cast<ListItem>().Where(x => x.Selected);
now you will have a Collection that you can check / code against
also make sure that this code is being fired and or check if there is a PostBack
you can check this by checking if(!Is.PostBack){ }

My money is on you are re-binding the controls on every postback, instead do this:
if (!Page.IsPostBack)
{
// Only bind controls on initial page and let viewstate remember what the user did
}

ASP.Net: GridView control and combobox woes

I've got a GridView control and Combobox control that are both successfully populated in my Page_Load event (within a block that checks for IsPostBack == false).
I've got an empty button 'btnClick' event handler which will reload the page when clicked. Both the GridView and Combobox controls have their EnableViewState property set to True. The behaviour I was expecting and hoping for was:
Page will reload with the GridView control still populated.
Page will reload with Combobox still populated and the item selected by the user still set as the selected item.
Unfortunately, the behaviour I'm getting is as follows:
GridView control is now empty and shows no data.
Combobox is now empty.
Code as follows:
public MyPage()
{
this.Load += new EventHandler(Page_Load);
}
protected void Page_Load(object sender, EventArgs e)
{
if (IsPostBack == false)
{
DataAccessObj daObj = new DataAccessObj();
foreach (DataRow dataRow in daObj.GetAllData())
{
ListItem listItem = new ListItem(dataRow.ToString(), dataRow.Id.ToString());
myCombobox.Items.Add(listItem);
}
IncidentGrid.DataSource = daObj.GetIncidentsByReportedById(0);
IncidentGrid.DataBind();
}
}
protected void btnSubmit_Click(object sender, EventArgs e)
{
// Do nothing
}
What I would like to do is allow the user to select an item from the Combobox. Upon clicking Submit, the GridView would be repopulated (based upon the selected item). The Combobox will remain populated and show the last selected item.
Can someone help explain where I might be going wrong? TIA

When you click your button, the page is posted back, in your page load, if it is a postback you need to databind the grid appropriately you need to add a condition to your page load event like
Firstly on your btn_click, you need to store the id selected with something like:
if (myCombobox.SelectedItem != null)
{
if (int.TryParse(myCombobox.SelectedItem.Value, out reportedById) == false)
{
reportedById = 0;
ViewState["reportedById"] = reportedById; // Need to remember which one was selected
}
}
Then On your Post Back
else (IsPostBack)
{
if (ViewState["reportedById"]) != null)
{
IncidentGrid.DataSource = daObj.GetIncidentsByReportedById(Convert.ToInt32(ViewState["reportedById"]));
IncidentGrid.DataBind();
myCombobox.SelectedItem.Value = ViewState["reportedById"].ToString(); // set combo
}
else
{
IncidentGrid.DataSource = daObj.GetIncidentsByReportedById(0);
IncidentGrid.DataBind();
}
}