Disabled textbox losses viewstate - c#

I am dynamically generating the form based on the drop down selected.
The form consists of fields (data entry for decimal values + few text fields). Have to add all the decimal values at the end and update the Total TextBox with that value. Total Textbox is disabled.
When I click Save button on the form after the user have entered their values, whole form is persisted in viewstate except the disabled textbox. When I enable the textbox, everything works fine. Mind you, I am dynamically generating the form and updating the value of the total textbox using javascript to calculate (adding all decimal fields).
P.S. I am doing everything right for persisting the viewstate.
So what has the enabled/disabled got bearing on the viewstate

Basically, I added two statements to get it working.
txtBox.Attributes.Add("readonly", "readonly");
txtBox.Style.Add("color","gray");
When I used txtBox.Enabled = false, it didn't persist viewstate but did it alternatively using above two statements in my code-behind page

Yes, disabled form element will not send it's value to server side, you can look request header. disabled element not appeared at "get" or "post" collection.
If you want set user can't edit it, you can set it as readonly.

Add javascript on the page:
function enableTextBoxes() {
$("input[type='text'][disabled='disabled']").removeAttr("disabled");
}
And add to server code (in Page_Load, PreRender or some else method)
ClientScript.RegisterOnSubmitStatement(typeof(Page), "enableTextBoxes", "enableTextBoxes();");
If you use UpdatePanels then utilize the ScriptManager.RegisterOnSubmitStatement method

Please create custom text box rather than using actual textbox instance.
inherit textbox in your custom textbox and add this textbox in your dynamic form.

Related

How to update changed field controls in asp.net webpage

I have a big form which contains almost 40 controls including text area , text box, calendar control. the data in form is getting populated from database. There is option to update the details of the form. I have to save only the changed controls.
Also I have to maintain track like which users has updated which fields.
Two Methods:
You can use onchange function to detect the value of which controls have been changed.
But, some user can just click on the text box but not change the value. In that case, use 2nd method.
Find default value of the control set from DB during load & compare it with updated field value by the user. every control has the different field where it stores default values, you will have to check it out.

Asp.net Textbox.Autopostback causes another issue

I have dropdown and texboxes and one button on the form. I'm using 'autopostback=true' for all the form elements. When you fill the form you need to push 'send' button. But because of texbox.autopostback, you need to push 2 time to send form.
If you select dropdown lastly, then there is no problem. But if you're filling textboxes than you need to click 2 time to send form.
Is there any solution for it? I must use textboxes.autopostback='true' but need some solution.
Thanks,
UPDATE:
All controls stays in updatepanel element.
Set a hidden field value to "1" when textbox posts back and its value is valid, else set the hidden field value to "0"
On client-side, in pageLoad event, automatically click the button if the hidden field value is "1". So, to the user button is only clicked once and your auto submitting the form when text post back returns.
Both the above points need to be done in your code-behind.
The result of of this logic will enforce a consistent workflow, where the button can be clicked only once to submit the page.

how do I save custom user control viewstate during postback?

I have written the user control InputDetails that has a few text boxes and a few radio boxes inside it.
I add it dynamically during Page_Load:
if(!Page.IsPostBack()){
InputDetails input = (InputDetails)Page.LoadControl("InputDetails.ascx");
PlaceHolder1.Controls.Add(input);
}
but when I refresh the page, the control is gone, so I'm asking, how do I save the user control in the viewstate that it has been added, so it automatically reloads it next time. Better yet, how do I read the values put in the text boxes of the user control when the page is posted back? I need to be able to add multiple InputDetails on a single page so saving it would be useful.
If you add a control to the page dynamically, you have to recreate it after each postback.
Try to remove the if (Page.IsPostBack()) line and check if it works :).
For each control you create, you should also set the same ID value each time it's created.
If there are no other issues, the ViewState should then be able to save state of the controls across postbacks.
In order to read the values, you can:
add some public properties to your user control in order to get access to the values you need
or
use TextBox txtBox = (TextBox)myCustomControlObject.FindControl("nestedTextBox") method to find (more information here: http://msdn.microsoft.com/en-us/library/486wc64h.aspx)
You can load user controls / server control dynamically using AJAX also and viewstate requires controls ID to store the viewstate properly.
would you pls go through this link for more info

ASP.NET VS2008 C# - dropdown list - postback

How can use a dropdown list without the autopostback=true.
The value on the server is not being changed according to the one selected from the client side. As I already stated I do not wish that for each dropdown I have the autopostback will trigger a post back.
Any time I have lost the value of the drop-down it is because I messed up and repopulated the drop down before handling the value change. For me, it has been drop-downs that I need to do something special with like add item attributes for Javascript, etc. This is data that needs to be added on every page load (aka data that is not persisted in the drop down like the names and values of each item). In these cases I have done this work on load, then I try to retrieve the value later in the page lifecycle and DOH!
Here is the page lifecycle:
http://msdn.microsoft.com/en-us/library/ms178472.aspx
Dollars to donuts that is what is happening. You are probably just reloading the items before you get to handling whatever postback event you are using to grab the value. If you are doing this and cannot get around this work flow, just save the selected index at the beginning of the logic that populates the drop-down, then set the selected index of the drop down with that value when done.
it'll be saved in the viewstate, so the value will be correct when you do eventually post back, and if you're really desperate to get the current value without a postback, javascript would be the way to do this.
Worst case you can grab the value right off the request object:
string selectedID = Request[DropdownControl.UniqueID];
You should make sure you are only filling the select box with options during the initial page load, and not again during the postback
if (!this.Page.IsPostBack) {
//fill select box here
}

Form post doesn't contain textbox data [ASP.NET C#]

I have several "ASP:TextBox" controls on a form (about 20).
When the form loads, the text boxes are populated from a database.
The user can change the populated values, and when they submit the form, I take the values posted to the server and conditionally save them (determined by some business logic).
All but 1 of the text boxes work as intended.
The odd box out, upon postback, does not contain the updated value that the user typed into the box.
When debugging the application, it is clear that myTextBox.Text reflects the old, pre-populated value, not the new, user-supplied value.
Every other box properly shows their respective user-supplied values.
I did find a workaround.
My solution was to basically extract the text box's value out of the Request.Form object: Request.Form[myTextBox.UniqueID], which does contain the user-supplied value.
What could be going on, here?
As I mentioned, the other text boxes receive the user-supplied values just fine, and this particular problematic text box doesn't have any logic associated to it -- it just takes the value and saves it.
The main difference between this text box and the others is that this is a multi-line box (for inputting notes), which I believe is rendered as an HTML "textarea" tag instead of an "input" tag in ASP.NET.
Are you initially loading the data only when !Page.IsPostBack? Also, is view state enabled for the text box?
this happens to me all the time.
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
// populate text boxes from database
}
}
I would second Jonathan's response I would check your databinding settings.
If you do not need ViewState for the textboxes (i.e. no postback occurs until form submit) then you should disable it.
It sounds like you are not having problems saving the data (since you said you have managed to get the control to read the correct data back). Therefore, I would say the problem loads in your databinding code.
Remember the order of the page lifecycle, and where you are databinding your form.
PreInit
Init
Load
Your Control Event Handler
If you are reading the value in the Control Event handler, yet databinding in Init or Load, you'll have the old value.
The trick is to always databind in the correct event, or check for postback and don't databind then.
Are you initially loading the data only when !Page.IsPostBack? Also, is view state enabled for the text box?
I had almost forgotten to check the ViewState, but ended up remembering to verify that it wasn't disabled before making my post here on SO. I even set EnableViewState="true" to make sure.
I did find the solution, and it coincided with most of the answers here. The form was indeed loading its data more than once (which is intentional behavior). I implemented some special code for this field, and all is well.
Thanks for your replies, all!

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