php checkboxes retain values from page to page - php

Question

I have form page calling a function that pulls 2 random names from a mysql database (called by php function pairsim()). I want to create a group of checkboxes that will create conditions that I can use to limit to mysql pulls. These conditions then need to live on until the user changes the configurations (update button below).
I am hoping to create an array of checked values to use as a condition until the user updates his configurations again. Unfortunately, I can't get the array to persist while going page to page. I am also having trouble creating an array to pass back into the pairsim(). Forgive my ignorance, is there anyway to accomplish what I am trying to do?
select_checkbox.php:
<?php
session_start();
$_SESSION['G'] = isset($_POST['pG']) ? 1 : 0 ;
$_SESSION['D'] = isset($_POST['pD']) ? 1 : 0 ;
$_SESSION['W'] = isset($_POST['pW']) ? 1 : 0 ;
$_SESSION['C'] = isset($_POST['pC']) ? 1 : 0 ;
?>
<button class="btn btn-success" type="button" data-toggle="collapse" data- target="#collapselimit" aria-expanded="false" aria-controls="collapselimit">
Limit Names
</button>
<div class="collapse container-fluid" id="collapselimit">
<form role="form" method="post" action=<?php pairsim() ; ?>>
<div class="panel panel-default">
<div class="panel-body">
<p><b>Position Limited:</b><br></p>
<!--create array with checked values to include to mysql function-->
<label class='checkbox-inline'><input type='checkbox' name='positionsel[]' value='pG' checked>Goalies</label>
<label class='checkbox-inline'><input type='checkbox' name='positionsel[]' value='pD' checked>Defensemen</label>
<label class='checkbox-inline'><input type='checkbox' name='positionsel[]' value='pW' checked>Wingers</label>
<label class='checkbox-inline'><input type='checkbox' name='positionsel[]' value='pC' checked>Centers</label>
<div>
<!--locks in checkbox configuratons-->
<input type="submit" class="btn btn-success btn-lg" value="Update"/>
<!--script below to check/uncheck all-->
<input type="button" class="btn btn-default btn-lg" id="CheckAll" value="Check All" />
<input type="button" class="btn btn-default btn-lg" id="UncheckAll" value="Clear All" />
</div>
</form>
</div>
</div>

Answer 1

I see a few errors here, I'll try to go in procedural order.
Your checkboxes all use the same name, so the resulting post var would be $_POST['positionsel'];. So your existing session check is always going to be false.
BTW the output var_dump($_POST['positionsel']); with everything checked would look like:
array(4) {
[0]=>
string(2) "pG"
[1]=>
string(2) "pD"
[2]=>
string(2) "pW"
[3]=>
string(2) "pC"
}
Fix:
session_start();
$checkBoxValues = array('pG', 'pD', 'pW', 'pC');
foreach($checkBoxValues as $check)
{
if(in_array($check, $_POST['positionsel']))
{
$_SESSION[$check] = true;
} else {
$_SESSION[$check] = false;
}
}
This will check the $_POST variable for the checkbox values, if it exists that means it was checked.
What this will then cause is a situation where if you do not submit a form, then no post value will process, causing the $_SESSION variables to be wiped. TO prevent this, we need to check if the form was in fact submitted. A cheap way to do that is to name the submit field:
<input name="submitted" type="submit" class="btn btn-success btn-lg" value="Update"/>
And before the foreach, do check for it:
if(isset($_POST['submitted']))
{
$checkBoxValues = array('pG', 'pD', 'pW', 'pC');
foreach($checkBoxValues as $check)
{
if(in_array($check, $_POST['positionsel']))
{
$_SESSION[$check] = true;
} else {
$_SESSION[$check] = false;
}
}
}
Now the session vars will only be overwritten if the form is actually submitted.
Next, you need to change your check boxes to only be "checked" if they were in fact checked:
<label class='checkbox-inline'><input type='checkbox' name='positionsel[]' value='pG' <?PHP if($_SESSION['pG']) { echo "checked"; }?> >Goalies</label>
<label class='checkbox-inline'><input type='checkbox' name='positionsel[]' value='pD' <?PHP if($_SESSION['pD']) { echo "checked"; }?> >Defensemen</label>
<label class='checkbox-inline'><input type='checkbox' name='positionsel[]' value='pW' <?PHP if($_SESSION['pW']) { echo "checked"; }?> >Wingers</label>
<label class='checkbox-inline'><input type='checkbox' name='positionsel[]' value='pC' <?PHP if($_SESSION['pC']) { echo "checked"; }?> >Centers</label>
That should then allow the form to reload with the already configured checkboxes, preserving your preferences across resubmits & new page loads as long as the session stays alive.
In this example I changed your session variable names to the check box values, so keep that in mind if you paste it over as you'll need to adjust it anywhere else you use the session (or adjust my code to use your original varnames).