radiobuttons

[Yaak]

Hi,

I have this form in a php page:

<form method='post' name='somename' action='getdata.php'>
<input type=radio name=someName value=1>
<input type=radio name=someName value=2>
</form>

on the page 'getdata.php' I want to retrieve the value of the selected radiobutton:

$someVar = $_form['someName']

and later save this to a database. However, if the user selected none of the 2 posibilities I get an error, which is logical, because the radio button did not get posted (no value).

Is there a function/way to check if this form field has been submitted?

thanks,
Yaak.

(quite obvious I'm a newbie, not? 🙂 🙂

[mrmufin]

There's lots of ways to do this; the methods I typically use include one of the following:

1. Throwing a hidden field into the form and checking for its value;

2. Sticking a name/value pair onto the submit button, which is what I do more often.

<form method="post" name="somename" action="getdata.php">
<input type="radio" name="someName" value="1">
<input type="radio" name="someName" value="2">
<input type="submit" name="button" value="Submit">
</form>

On the server side, you can do something like this:

if($HTTP_POST_VARS['button'] == "Submit") {
	// form was submitted, since the value of 'button' is equal to 'Submit'
	switch($HTTP_POST_VARS['someName']) {
		case '1':
			// one radio button was selected code goes here
		break;
		case '2':
			// two radio button was selected code goes here
		break;
		default:
			// form was submittted but no radio button was selected code goes here
		break;
	}
} else {
	// form was not submitted
}

Note that if you're using a version of PHP >= 4.1.x, you can substitute $HTTP_POST_VARS with $_POST. However, $HTTP_POST_VARS will still be available, though deprecated.

Have fun...

[Yaak]

I've tried what you suggested, but when no radiobutton is selected I get the following error message:

Notice: Undefined index: someName

btw: I'm using the $_post variable instead of $HTTP_POST_VARS

... any other solution?

thanks!
Yaak

PS: I'm using PHP version 4.2.2

[mrmufin]

Please post the PHP code you're using...

[malbera]

if($HTTP_POST_VARS['button'] == "Submit") {
    // form was submitted, since the value of 'button' is equal to 'Submit'
    if (isset(_POST['someName'])) {
   //if first radio is 'checked'
   //CODE...
   }


   if (isset(_POST['someOtherName'])) {
   //if second radio is 'checked'
   //CODE...
   }
   else {
    //no radio button checked

}

}
else {
    // form was not submitted
}

[Yaak]

this is on the form page

<tr> 
  <td><font size="1"> 
    <input type="radio" name="presentation" value="poster">
Poster </font></td>
  <td><font size="1"> 
     <input type="radio" name="presentation" value="oral">
Oral communication</font></td>
</tr>

this is the savedata.php page:

switch ($_POST['presentation'])
	{
		case "oral":
			$presentation = "oral";
			break;
		case "poster":
			$presentation = "poster";
			break;
		default:
			$presentation = "not selected";
	}

I realize that the the first 2 cases in the switch could be deleted (I think), but still...

thanks,
Yaak

[malbera]

When you submit a form with radio buttons, the php script doesn't get the value of the radio button, only if it is checked or not.
if it isn't, the script doesn't get anything at all about that radio button
that's why you get that error when no radio button is checked...

[Yaak]

... and then back to my original question:
Is there a way in PHP to check if a form field has been submitted?
something like ifExist($_POST('FieldName')) ?

thanks,
Yaak.

[mrmufin]

Originally posted by malbera
When you submit a form with radio buttons, the php script doesn't get the value of the radio button, only if it is checked or not.
if it isn't, the script doesn't get anything at all about that radio button
that's why you get that error when no radio button is checked...

This is absolutely not the case. Since grouped radio buttons all have the same name, only their values differ, therefore the value must be available to PHP. Otherwise, we don't know which button was selected...

The code I posted earlier works fine using the $HTTP_POST_VARS array on PHP 4.0.6. If the $_POST array behaves differently when using radio buttons in newer versions of PHP than the deprecated $HTTP_POST_VARS array (and I see no logical reason why it should), the PHP developers have not made this point abundantly clear.

I do not dispute the fact that using isset(), as your code example shows, will work fine. However, simply knowing that a button is set does not tell the application which button was selected...

As far as knowing whether or not the form was submitted, by applying a name/value pair to the submit button (as my earlier post also suggests), simply test to see if the $_POST['button'] is the same as the value="" attribute of the button. If it's the same, the form was submitted. If not, the form was not submitted.

[Yaak]

I think.
When using Internet Explorer and submitting a form where a radiobutton group has nothing selected, the browser does not send any data related to this group (not even the groupname) back to the server:

I have tried to change the 'post' to 'get' to see what is actually sent to the browser, and nothing for the radiobuttons get sent.
This is why it does not seem to exist for php.

Although this does not exuse php to not be able to resolve this.
some function like: is_var('varname') should be welcome.

Anyone have a solution that works (without having to resort to a dummy radiobutton that sends a value in case nothing was selected?

thanks!

...PS: I cannot use Netscape for this specific form due to DTHML features I need that Netscape doesn't support

[mrmufin]

Originally posted by Yaak

When using Internet Explorer and submitting a form where a radiobutton group has nothing selected, the browser does not send any data related to this group (not even the groupname) back to the server:

This is true with every browser that I've worked with, hence the 'default' condition in the switch statement on my earlier post, which should accomodate for every condition wherein the name of the POST variable does not match a case, INCLUDING a condition where the POST variable does not exist at all in the $_POST array.

If you need the radio button value (and I'll assume that you do), try a malbera's suggestion, using isset():

if(isset($_POST['someName'])) {
	echo $_POST['someName'];
} else {
	// the radio button was not selected
}

which should show the value of the radio button selected.

[Yaak]

... it works!
I thought I had tried the isset() function before, but appearently not.
This is what I used:

	if (!isset($_POST['someName']))
	{
		$presentation="not selected";
	}

and this works, even if none of the radio buttons have been selected.

Thanks to all that helped me! 😉 🆒
where shall I send that bottle of champagne to? 🆒 :rolleyes: