I have a disabled TextBox that I am editing the value of on the client side with JavaScript. When I try to retrieve the value on the server side it does not reflect the change made on the client side. If I set the TextBox's enabled attribute to true I can retrieve the value, but the user is able to put focus and edit the TextBox.
Is there a sane way to keep the user from giving focus and editing to the TextBox?
Use the textbox's ReadOnly property.
Edit: Based on OP's comment, this will probably not do the trick then.
Edit 2: From DotNetSlackers:
So what's the difference between these
two properties and why do both exist?
There are two differences between
these two properties, a trivial
difference and a subtle, profound one:
The two properties emit different markup. When you set Enabled
to False, the TextBox injects the
attribute disabled="disabled" intoits
rendered HTML. When you set the
ReadOnly property to True, the
attribute readonly="readonly" is
injected.
According to the W3C spec on HTML forms, disabled controls areNOT
"successful," while read-only controls
MAY BE "successful." A "successful"
control is one whose name/value pair
is sent back to the browser through
the POST headers or querystring.
Therefore, disabled controls are NOT
sent back to the ASP.NET page, while
read-only controls may be, depending
on the User Agent. (In my tests,both
IE 6and FireFox 1.5 send along the
read-only TextBox input.)
......
If you encountered this problem in
ASP.NET version 1.x you might have
found the TextBox's ReadOnly property
and used that instead of setting
Enabled to False. You could still have
a page's ViewState disabled and set a
read-only TextBox Web control's Text
property programmatically because the
TextBox value is sent back through the
form submission for read-only
controls. However, in ASP.NET version
2.0, things change just a bit, as noted by Rick Strahlin his blog entry
ASP.NET 2.0 ReadOnly behavior change
when EnableViewState is false. With
2.0, the TextBox control'sReadOnly property's behavior has changed
slightly. From the technical docs:
The Text value of a TextBox control with the ReadOnly property set to true is sent to the server when a postback occurs, but the server does no processing for a read-only text box. This prevents a malicious user from changing a Text value that is read-only. The value of the Text property is preserved in the view state between postbacks unless modified by server-side code.
What happens is that the client sends
along the value of the read-only
TextBox through the form values, but
the ASP.NET 2.0 engine does not take
that value and assign it to the Text
property of the TextBox on postback to
help protect against a malicious user
changing the read-only TextBox value
themselves. But this brings us back to
our earlier problem - if the value
isn't specified in the postback (or is
ignored, in this case) and ViewState
is disabled, the value will be lost.
Eep.
Rick'sworkaround was to just manually
read the value from the request
headers (this .TextBox1.Text =
Request[this.TextBox1.UniqueID];),
which poses a security risk and
introduces the problem that 2.0
addresses. The optimal approach is to
requery the value from the database
(or wherever you initially got the
programmatically-set value for the
read-only TextBox).
The moral of this blog post is that if
you have read-only data you can use
either disabled or read-only form
fields, it really doesn't matter
whether or not you receive back the
value of the form field in the form's
submissions. It shouldn't matter
because you shouldn't be
trusting/using that data to begin
with! If you have read-only data,
don't re-read it from a data stream
that the end user can tinker with!
Source
Browsers don't post values back in disabled input controls, as you've discovered. Probably the easiest way to work around this is to hook onto form submission, and re-enable the input as the form is being submitted; the user won't have a chance to edit the value, and it should get posted with the rest of the request.
An alternative might be to inject a hidden element into the form; this could either be maintained by your script, mirroring the displayed value, or added at the end, in a similar fashion to the above.
Related
I have a fairly complex form (user control actually) with one textbox control on it that needs to NOT post back. Is there a way to remove a control from the post? Yes, this textbox is editable.
More info: This is for a credit card processing form, so the "final" submit will post to another site's page. However, prior to this there is plenty of server-side processing that goes on. I know that I can move the the credit card number text box to another page - but this requirement came very late and I'll trying to not have to re-work a lot of things.
The easiest way would be to use an html input as opposed to an ASP TextBox. These are not accessible from code if runat="server" is not set on them.
Or use the viewstate property (http://msdn.microsoft.com/en-us/library/system.web.ui.control.enableviewstate.aspx)
So the situation is that you have a form that is rendered in the user's browser with an action pointing to a different site and you need to make sure that one of the form fields will not be sent when the form is submitted.
Sounds to me like you cannot in that case make absolutely sure that the value is not posted. There are many different possible ways to solve this using javascript (disable input, clear value, etc before submit) but if scripting is turned off I think you're out of luck.
But since you can prepare for sending the form to the other server (change action on form or enable button with PostBackUrl), I guess you could also then set the Enabled property on the textbox to false. That would mean that it can no longer be edited on the final page beforr posting to the other server. Or you could hide the textbox a (so it's not renered at all) and show the field as a label or literal instead.
But even then you still have to somehow make sure the secret value is not included in the viewstate of the form. Which it will be in case you use a label or literal. And also for a textbox that was disabled or hidden on the last postback. Normally the viewstate is just a base64 encoded string so it would be trivial to find the credit card number from there. You could probably fix this by turning off viewstate for the control in question (or even for the whole page) in the last post back to your page before setting the form up for posting to the other server.
If you cannot tell for sure which will be the last postback to your server, then I think you're out of luck without more significant changes. Sorry to be a downer. Some seemingly trivial things are just hard with Asp.Net web forms.
Maybe you could add a separate page that you populate with just the data that you need to send to the other server and have that a sort of "Confirmation page". In that page you could turn off viewstate, show all the data summarized (using labels and literals etc) and the actual data to post could be included in the form as hidden fields. Then that form would post to the other server when the user "Confirms".
I have a html element:
<div id="myElement" class="someClass" onclick="setText(this.innerHtml)" runat="server">text</div>
I want to be able to change this element on the client side using some jquery like so:
function setText(text) {
$(".someClass").text(text);
}
--OR--
function setAttribute(text) {
$(".someClass").attr("myAttr",text);
}
Once I do this I want to grab this element's new text or new attribute and then store the value of either or, server side. I should note that I then postback to the server using a LinkButton. It is at this time that when I look at the element the default text is still present or the new attribute I added is missing.
Can someone explain why the element does not get updated on the server and how I can get it too?
I believe the problem you are facing is due to the type of html element you are using, a div. If you simply replace the div with an input of type "text", it will work as you expect it, allowing you to read values on postback. Only form elements are sent during form submission/postback.
An example of this is how web-based WYSIWYG text editors work. You type and edit in a div, but in the background all changes you make are stored in a hidden field. This hidden field is used to post the information back to the server.
This method can work but it depends on the type of element that you modify and the type of attribute. Remember that all your controls get recreated on each request right? The only reason on why exactly you can pull out information in you button event is because asp.net pulled the data from the request ( or viewstate) on the LoadViewState event and replaced the default values of your control by this data.
If you div element is not a server side panel control ( this is the asp.net control that will render a div element) , it cannot work. If you make it a panel control, I'm not even 100% sure that this is passed in the Page.Request (especially the attributes)
What I would do is copy the value that you modified in you div element into a hidden field that can be easily accessed server side and get this new attribute form there.
Attributes are not posted to the server, like at all (other than value, snerk). Only the name / value pairs of the items are, and (assuming you are using traditional webforms) the data that is contained in view state.
If you want to change items like this, and then access it on the server, you would need to post this data either on the query string, or as a key value pair (which you would then need to set on your server objects).
Otherwise, this is impossible.
I have to set dropdownlost to read only. I can set enabled =false. But I cannot set font color to regular dropdown text. It will show like blur. The samething I did textbox.readonly=false. There we can see font same as regular text, no change.
The same way I want read only for dropdownlist. Is there any way we can do with CSS or javascript or jQuery ?.
Thanks in advance
There is varying browser support for this. Typically, Internet Explorer provides fewer opportunities to override the default greyed out look for disabled controls, than the other main browsers. I have struggled to do this in the past across all browsers. I would be interested to see some answers here that do this rather than my advice not to do it...
I would question why you are doing this. Your users will be used to the default look of disabled controls. It is a visual cue to them that the control is disabled. I would urge you not to disrupt this subtle visual que that people are very very used to.
Unless you can give a compelling reason to do this of course.
One way to hack this would be to not disable the dropdown list at all (taking care of the styling). Then, add an event handler to the change event that sets the dropdown back to the original value. You would have to store the original value, probably in an input of type hidden, and when you handle the change event, first check whether the value is the same as the stored value. If not, set it back. If you don't make this check you will get an infinite loop, because setting it back to the original value will call the change event again.
I'm trying to persist the contents of a textbox through a postback, and I've exhausted all of my effort but can't get it working right.
What should happen is:
User selects a radiobutton
Depending which button was
selection, a usercontrol is loaded
to specify some data and a viewstate
to say which enum type it's
equivalent to.
When they click
save, if the UserControl is just a
textbox input - the simplest), the
contents are read and saved, then
saved to the database with the
format(the radiobutton choice) so
they can be deserialized again
later.
The page posts back, and
the value and format are read from
the database, then the right control
is loaded.
The problem is - the first time the page posts back, it works. Every other postback it resets to the default value of the textbox.
I have a very similar setup elsewhere, so I'm thinking it might be a minor thing I'd never think of. There's a lot of code, so it might be easier to talk about what to do (load the dynamic control, populate the values etc) rather than how to do it.
There was actually a bug in my original code which meant it would never have in the way I was using the modified version. Apparently state is restored in Page_Load, so any controls need to be initialized by to have their values restored.
Creating the control in Page_PreLoad, then populating it after Page_Load solved the problem.
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!