I've two ListBox (second one is empty on page load) and two buttons which switch items between those ListBox.However,im using Jquery two switch items,which means there are no Postbacks.Once,ive finished,i click another button to save the items from the second List,this time using PostBack.
When it runs on server,ASP.NET does not recognize any item on the list,showing listbox2.items.count = 0(zero),but im sure that list does have items.
I wonder if add items to the list without postbacks is the problem;
Any suggestions?
code trying to get list:
try
{
estabelecimentos = new List<int>();
int x = lstSelect.Items.Count;//always 0,but list isnt empty
estabelecimentos = lstSelect.Items.Cast<ListItem>().Select(v => int.Parse(v.Value)).ToList();
}
catch(Exception ex)
{
divErro.Visible = true;
lblErro.Text = ex.Message;
return;
}
You are correct, when you postback to the server the datasource of the second list is read out of the ViewState (which had no items in it). You could store the second list's data in a hidden input (client side) or you could do postbacks to update the second list.
Related
When I use the code below, I remove the datatable values, but the data table structure still exists and displays empty fields (see pics) with the DOM explorer showing an empty table and table rows.
How can I clear the datatable values and the table itself? This way when I repopulate search again, the empty smaller table isn't present?
lvwOutput.Items.Clear();
lvwOutput.DataSource = null;
lvwOutput.DataBind();
Before
After items.clear and datasource = null
This is ridiculous and I believe there is a better way to do this, but the never ending server/client battle makes this harder than it should be. My listview binded to a datatable is called lvwOutput.
In my btnClear I had to put the following. You cannot hide the element or clear the items in the server side asp code for this to work
ScriptManager.RegisterStartupScript(Page, GetType(), "emptyTable", "javascript:emptyTableRows(); ", true);
In my javascript code I had to put the following, this clears the client code
function emptyTableRows(){
var tableHeaderRowCount = 0;
var table = document.getElementById('lvwOutputTable');
var rowCount = table.rows.length;
for (var i = tableHeaderRowCount; i < rowCount; i++) {
table.deleteRow(tableHeaderRowCount);
}
}
And then in the portion of my code that would display the listview and datatable when the user initiates another sql search. This clears the server side.
lvwOutput.Items.Clear();
lvwOutput.DataSource = null;
lvwOutput.DataBind();
You can create a property the stores the data table in session that way you can access it during the click event.
DataTable dtbleDataSource
{
get
{
return Session["dataSource"] as DataTable
}
set
{
Session["dataSource"] = value;
}
}
In your click event you can say:
dtbleDataSource.Reset();
I want to create dynamic text boxes during run time.
Suppose im gettng a text from a database as "# is the capital of India" now i want to replace that "#" by text box while it is rendered to user as below
<asp:TextBox runat="server" id = "someid"></asp:TextBox> is the capital of India
Im able to get the textbox and text as combination. However I cannot access the textboxes with the given id and when any event occurs on the page the textboxes are lost as they logically does not exist untill their state is stored.
I also went through the concepts of place holder and Viewstate to store the dynamically created controls and make their id's available for the methods, but as far as I tried I could not meet the textbox and text combination requirement.
Im looping over the entire text recieved from database and checking if there is any"#". Is yes then i want to replace it with a textbox on which i can call methods to take back the value entered in the text box to database and store it.
eg: text is "#" is the capital of India
for (int i = 0; i < que.Length; j++) //que holds the text
{
if (que[i] == '#')
{
//Textbox should be created
}
else
{
//the texts should be appended before or after the textbox/textboxes as text demands
}
}
On button click I'm passing request to database, which will send me necessary details i.e. question text, options and also saves the current checked value etc.
protected void BtnLast_Click(object sender, EventArgs e)
{
CheckBox1.Checked = false;
CheckBox2.Checked = false;
CheckBox3.Checked = false;
CheckBox4.Checked = false;
QuestionSet q = new QuestionSet();
StudentB b = new StudentB();
q = b.GetQuestion(1, 1, qid, 'L', 0, Checked, date);
qid = Convert.ToInt32(q.Question_Id);
Checked = q.Checked;
if (q.Question_Type == 11) //indicates its objective Question
{
//ill bind data to checkboxes
}
else if (q.Question_Type == 12) // indicate its fill in the blanks question
{
for (int j = 0; j < que.Length; j++)
{
if (que[j] == '#')
{
count++;
string res = "<input type = 'text' runat = 'server' id ='TxtBoxFillUp" + count + "'/>";
htm = htm.Append(res);
}
else
{
htm = htm.Append(que[j]);
}
}
}
}
Any help will be greatly appreciated, thanks in advance.
Adding control in the way you do it won't create control as asp.net creates it. You do have to create controls as usual .net object.
TextBox myNewTextBox = new TextBox() {};
// Set all initial values to it
And add this cotrol to placeholder or panel, whatever you use. Keep in mind that asp.net page events fire even if you use update panel, so in order to maintain state and events of newly created controls you have take care of creating such controls long before page's Load event fires. Here is my answer to another simialiar question.
Seeing the requirements you have:
1.) You need to use JavaScript. Since the ASP.NET will not recreate controls which are dynamically added. Dynamically added controls need to be recreated after every postback. This is the reason why your TextBoxes are Lost after every postback.
2.) You can write JavaScript code to Hide and show the textboxes for blank texts since at every button click you can call Client side functions using: OnClientClick() property of buttons.
3.) Also to Get the TextBoxes using ID property, add them in Markup( .aspx ) portion itself.
I have a listView control which is bound to an object datasource. In the ListView1_ItemDataBound event, I am generating some dynamic controls. I do this because depending on a particular column value, i might need to generate textbox, radio button, check box etc.
Some code here:
ListViewDataItem item = (ListViewDataItem)e.Item;
typez = Convert.ToInt32(DataBinder.Eval(item.DataItem,"Type").ToString());
if (typez == 1) //1 means generate radibutton
{
string[] options = DataBinder.Eval(item.DataItem, "QuestionDetail").ToString().Split(new string[] { delimiter }, StringSplitOptions.None);
questionID = Convert.ToInt32(DataBinder.Eval(item.DataItem, "Question_ID").ToString());
int optionCount = 1;
RadioButtonList rbl = new RadioButtonList();
//set ID for the radiobtnList to the questionid no.
rbl.ID = "mcq_" + questionID;
foreach (string s in options)
{
//adds the MCQ options to list item
ListItem li = new ListItem(Util.GetAlphabet(optionCount).ToUpper() + ". " + s, Util.GetAlphabet(optionCount).ToUpper(), true);
rbl.Items.Add(li);
optionCount++;
}
//PlaceHolder PlaceHolder1 = (PlaceHolder)e.Item.FindControl("PlaceHolder1");
PlaceHolder1.Controls.Add(rbl);
I have DataPager also. When I go to the next page I want to somehow capture the user response in the previous page. Otherwise, all the user response is lost. I tried using ListView1_PagePropertiesChanging event. But here I somehow do not seem to get the dynamic controls in the page.
I need to get the radio button selected value so that I can save it or put in some session variable so that when user comes back to this page he can see his previuos values.
Could someone please suggest some insight on what I am doing wrong.
Problem is that you have to create controls in OnInit, then ViewState persister can do it's job. If you do it after OnInit, in ItemDataBound, when Postback is triggered, controls doesn't exists and their's viewstate isn't deserialized.
To access values of radio buttons and get selected one, you have to look at Request.Form dictionary and find it.
I want to have an ASP.net page where the user can add rows to a grid view (think typing values into a textbox and clicking Add to add to the grid view). Clicking a submit button would then persist all rows to the database.
For a low traffic site, what reasonably easy solution would you recommend to achieve this?
I've done this a few times. The basic premise of my solution is that you load the data into a local collection, and store this in the ViewState of the page.
List<MyObject> lst = new List<MyObject>();
// Populate the list from the database here
// Store this list in the ViewState
ViewState["List"] = lst;
I then have a function which binds this list to the GridView, which I call in the first Page_Load, and any function which modifies this list:
function BindList() {
List<MyObject> lst = (List<MyObject>) ViewState["List"];
GridView1.DataSource = lst;
GridView1.DataBind();
}
To add a new item...
function cmdAdd_Click(object sender, EventArgs e) {
// Retrieve list from ViewState
List<MyObject> lst = (List<MyObject>) ViewState["List"];
// Add the new item
MyObject newObj = new MyObject(); // Populate this from your form
lst.Add(newObj);
// Update the list in the ViewState
ViewState["List"] = lst;
// Update the grid to show the new item
BindList();
}
When you want to persist all of the items to the database, simply retrieve the list from the ViewState.
I want to instantly update a status line indicating the number of checked checkboxes across all pages of an asp.net gridview. Right now I am only ably to count the number of checkboxes that are checked on the current gridview page.
Here is my code:
$(document).ready(initAll);
function initAll(){
countChecked();
$(".activeBoxes").click(countChecked);
}
function countChecked() {
var n = $(".activeBoxes input:checked").length;
$("#checkboxStatus").text(n + (n == 1 ? " vehicle is" : " vehicles are") + " selected on this page. ");
if( n == 0){
$(".activateButton").hide();
$("#checkboxStatus").hide();
}else{
$("#checkboxStatus").show();
$(".activateButton").show();
}
}
Keep a hidden text field on your page and everytime you check a box, call a javascript method that will write the 'id' of the checkbox to the hidden field. Each time you postback your page, serialise the hidden field's value to the session in your desired objects structure (be it objects, hash table, array etc).
Upon rendering the page, each checkbox can check the session object structure (that you have created before) and determine if the state of the checkbox was last checked or not.
You could use JQuery to loop through all checkboxes on the page and increment a counter if the checkbox is checked.
You can track the total selection in viewstate (or something similar) on page change. I did something similar tracking the selected row ID's in an array. In my case I had to re-check the items when they returned to the page. Additionally if you allow sorting the selection may move across pages.
Edit: Sorry this doesn't actually your Jquery question, but maybe it will help...
What you're missing is removing the ID. When checking rows and tempid is not checked make sure it is not in saveids.
Do you know that Google is your friend?
Selecting CheckBoxes Inside GridView Using JQuery
The WML Video
And without JQuery but for more perfectionist behavior (like the image below), try this link
alt text http://www.gridviewguy.com/ArticleImages/GridViewCheckBoxTwistAni.gif
I am using a viewstate to keep track of all checked items across all pages and rechecking them upon returning to the page.
I will have to add my viewstate value to the page total and somehow subtract overlapping totals. Since my jquery does not include an id, this will be tricky.
protected ArrayList savedIds;
if (ViewState["SavedIds"] == null) savedIds = new ArrayList();
else savedIds = (ArrayList)ViewState["SavedIds"];
List<int> activateList = new List<int>();
foreach (GridViewRow tt in GridView2.Rows)
{
CheckBox cb = (CheckBox)tt.FindControl("ActivateItem");
HiddenField id = (HiddenField)tt.FindControl("IdField");
if (cb.Checked)
{
int tempId = 0;
string tempId2 = id.Value.ToString();
int.TryParse(tempId2, out tempId);
activateList.Add(tempId);
}
}
foreach (int activateId in activateList)
{
if (!savedIds.Contains(activateId.ToString())) savedIds.Add(activateId.ToString());
}
ViewState["SavedIds"] = savedIds;