i have checkbox on the form
<input class="addToFavorite" type="checkbox" name="addToFavorite"> Add to favorite
now when form posting i check if this checkbox checked with this code. But it return true every time. how i can check if checkbox has been really checked?
boolean wantAddToFavorites = false;
if (isPayAction) {
wantAddToFavorites = request.getParameter("addToFavorite").equals("on");
}
FireBug result
as you see It always send its value
If you want to check on server-side if a checkbox has been checked or not, you should do the following:
1. Add a value to your checkbox
<input class="addToFavorite" type="checkbox" name="addToFavorite" value="addToFavourite"> Add to favorite</input>
2. Check this checkbox value on server-side
if(request.getParameter("addToFavorite") == null){
//checkbox not checked
}else{
//checkbox checked
}
In a checkbox, the value attribute holds the string that will be sent if the box is checked. By default it sends the string "on".
What determines whether it is checked or not is the checked attribute.
Example:
<input type="checkbox" name="check1" checked /> Sends "on"
<input type="checkbox" name="check2" /> Sends null
<input type="checkbox" name="check3" value="hello" checked /> Sends "hello"
<input type="checkbox" name="check3" value="hello" /> Sends null.
Related
I'm following this article
https://www.w3schools.com/howto/howto_css_custom_checkbox.asp
for a checkbox, but how do I set and get the check value?
As I need to a do a post back with the value.
<label class="container">Accept Offers?
<input type="checkbox" id="Offers" name="Offers"/>
span class="checkmark"></span>
</label>
change your code to this
<input type="checkbox" id="Offers" value="checkedValue" name="Offers"/>
If you see the Request.Form object or query-string (in case of HTTP GET submission) you will see the value, If this is not checked null will be seen or Request.Form will have not that key that belong to Checkbox.
I'm currently doing the following to compensate for boolean's not mapping well to radio buttons. I am stuck binding 1 and 0 to the value (instead of true and false) because of how the fields are read out of the observables. The value of Pref1/Pref2 come as true/false boolean values from the server. The key here is I want to not only data-bind the checked value of the radio button to match the true/false in the object, but I also want the boolean value of true/false to be written back into the GraduationClass object. My compensation code is not only ugly, but not scalable.
<input type="radio" value="1" name="radioGroup" data-bind="checked: Pref1" />Yes
<input type="radio" value="0" name="radioGroup" data-bind="checked: Pref2" />No
Save
function SiteSettingsViewModel() {
var self = this;
this.saveGraduationClass = function(graduationClass) {
// hack until i get a custom radio button binding
if (graduationClass.Pref1() == 1) {
graduationClass.Pref1(true);
} else {
graduationClass.Pref1(false);
}
if (graduationClass.Pref2() == 1) {
graduationClass.Pref2(true);
} else {
graduationClass.Pref2(false);
}
// ...ajax call to save graduationClass to the server
}
function GraduationClass(data) {
var self = this;
ko.mapping.fromJS(data, {}, this);
}
Here is example from knockoutJs website, that demonstrate how to use radio buttons with
"checked" attribute:
<p>Send me spam: <input type="checkbox" data-bind="checked: wantsSpam" /></p>
<div data-bind="visible: wantsSpam">
Preferred flavor of spam:
<div><input type="radio" name="flavorGroup" value="cherry" data-bind="checked: spamFlavor" /> Cherry</div>
<div><input type="radio" name="flavorGroup" value="almond" data-bind="checked: spamFlavor" /> Almond</div>
<div><input type="radio" name="flavorGroup" value="msg" data-bind="checked: spamFlavor" /> Monosodium Glutamate</div>
</div>
<script type="text/javascript">
var viewModel = {
wantsSpam: ko.observable(true),
spamFlavor: ko.observable("almond") // Initially selects only the Almond radio button
};
// ... then later ...
viewModel.spamFlavor("msg"); // Now only Monosodium Glutamate is checked
</script>
But I dont understand why you use two objects - "Pref1" and "Pref2" fro one radiobutton group "radioGroup"? In this case you just could use one object as in an example used "spamFlavor".
So, please, describe more ditaily what you want to bind: one radiobuttons group by one selected value, or something else.
Also you could use computed observables to calculate different values, please see example.
I'm using handlebars in a backbone.js rails app, and I have a Boolean field I'm populating with a checkbox.
When I load the edit page, the form is populated with the contents from the server JSON something like
{id:3,user:'test',checkbox:1}
now in my handlebar form, I want to show that the checkbox is 1.
< input type="checkbox" name="checkbox" value="1" {{#if checkbox}} {{bindAttr checkbox checked="isSelected"}}{{/if}} >
but this isn't returning the checked checkbox. I'd really like to just be able to say if checkbox==1, but I don't see how I can do that with handlebars.
Anysuggestions??
What you would usually do, is using a Boolean in the 'model'.
{
isChecked: true
}
and then
<input type="checkbox" {{bindAttr checked="isChecked"}}>
If the Boolean is true, it will render the checked property, and if the Boolean is false, it would omit the property. So if isChecked is true, then Handlebars would output
<input type="checkbox" checked>
and if isChecked were false, we would get
<input type="checkbox">
Which is what we want!
I also wrote a helper to do this. It doesn't use backbone.js, so may be an alternative for some:
Handlebars.registerHelper('checked', function(currentValue) {
return currentValue == '1' ? ' checked="checked"' : '';
});
Usage example:
<input type="checkbox" name="cbxExample" id="cbxExample" {{checked cbxExample}}/>
Would tick a checkbox if the supplied JSON was:
{"cbxExample" : "1"}
Resulting in:
<input type="checkbox" name="cbxExample" id="cbxExample" checked="checked" />
[my first post - hope that's helpful!]
It seems this ought to be dead simple, but I'm stuck. I've written some asp.net code that outputs a pair of radio buttons:
<p>
<label for='chkYapper'>Yapper</label>
<input type='radio' name='yapper' id='chkYapper' value='yapper' checked='<%=gblYapperChecked %>' />
<br />
<label for='chkNonYapper'>non-Yapper</label>
<input type='radio' name='Yapper' id='chkNonYapper' value='nonYapper' checked='<%=gblNonYapperChecked %>' />
if (registrationUser.isYapper == 1)
{
gblYapperChecked = "checked";
gblNonYapperChecked = "";
}
else
{
gblYapperChecked = "";
gblNonYapperChecked = "checked";
}
As expected, I get two radio buttons, "Yapper" and "Non-Yapper". However, even when I step thru my code and see that gblYapperChecked is "checked" and gblNonYapperChecked is "", Non-Yapper is always selected by default in the web browser.
What am I doing wrong?
UpdateHere is the HTML code as it actually appears in the browser. "Yapper" should be selected, but "Non-Yapper" appears selected instead.
<p>
<label for='chkYapper'>Yapper</label>
<input type='radio' name='yapper' id='chkYapper' value='yapper' checked='checked' />
<br />
<label for='chkNonYapper'>non-Yapper</label>
<input type='radio' name='yapper' id='chkNonYapper' value='nonYapper' checked='' />
Note that the HTML "checked" attribute is generally determined by being present or not present. See http://www.w3.org/TR/html401/interact/forms.html#adef-checked for the spec.
In particular what this means is that if you want it to be checked you cna have checked, checked=true, checked=checked and so on. So what you want is to not have the checked attribute at all if you don't want the checkbox selected.
I would advise structure such as:
<input type='radio' name='Yapper' id='chkNonYapper' value='nonYapper' <%=registrationUser.isYapper?"":"checked='checked'" %> />
This should eliminate your checked attribute entirely dependant on your isYapper boolean.
The "checked" attribute is weird, it has no value. If a radio button is checked, include the "checked" attribute by itself in the tag. If unchecked, don't do anything. See here:
http://www.htmlcodetutorial.com/forms/_INPUT_TYPE_RADIO.html
Are you setting dblYapperChecked before or after the control is created? Personally, I'd run the radio buttons on the server side and set the checked value on the control directly, but your method should work if the values are set soon enough (try initializing them to the expected values and see if that makes a difference...)
So I've got three RadioButtons, They're not in a RadioButtonList because I need to add some textboxes next to each of them.
I've added a GroupName, and on the front end they behave as expected. ONLY ONE appears checked at a time.
However in the code, if I do:
RadioButton1.Checked = true;
RadioButton2.Checked = true;
RadioButton3.Checked = true;
I would expect only the last one, RadioButton3, to be checked, because they all belong to the same group. This is not the case. All three evaluate to true.... how can that be?
I have to set them explicitly to false... am I missing something?
I think this is the correct behavior although it is not what you might expect.
Consider that a RadioButton is just a CheckBox with some extended functionality to automatically to give that exclusive checking functionality. In the background it is still a checkbox though. See the hierarchy from MSDN:
System.Object
System.Web.UI.Control
System.Web.UI.WebControls.WebControl
System.Web.UI.WebControls.CheckBox
System.Web.UI.WebControls.RadioButton
The output has all items with the attribute checked="checked" output for the input of type="radio". Eg:
<input id="rad1" type="radio" name="Test" value="rad1" checked="checked" /><label for="rad1">1</label><br />
<input id="rad2" type="radio" name="Test" value="rad2" checked="checked" /><label for="rad2">2</label><br />
<input id="rad3" type="radio" name="Test" value="rad3" checked="checked" /><label for="rad3">3</label>
From the Checked property documenation:
Checked (inherited from CheckBox):
Gets or sets a value indicating
whether the CheckBox control is
checked.
So the Checked property acts just like the CheckBox version with no functionality included to look for other controls in the same group and remove them which makes sense since it is a singular control.