how to handle checkboxes with statements and echo them - php

Question

hello i have the following problem:
i would like to create a filter for a search engine. i have some inputfields for specific search terms and beside a respective checkbox. so that looks like:
inputfield a: [_____] filter for a: on/off: [ ]
inputfield b: [_____] filter for b: on/off: [ ]
inputfield c: [_____] filter for c: on/off: [ ]
the code structure of that is:
first of all check if the inputfield is empty and the checkbox is set checked. in case of checked it will be unchecked after submit. the other way around, if just the inputfield is filled and the checkbox unchecked, it also will error out, that there is a mistake and the filter can't work. so i'm using for each filter an own error array like (the name and value of the first checkbox is name="filter_a" value="1") :
...
$checkbox_filter_a = $db->real_escape_string(htmlentities(trim($_POST['filter_a'])));
...
$filter_a = (!empty($checkbox_filter_a)) ? 1 : 0;
...
$errors_a = array();
if ($filter_a == 1){
if (empty($input_a)){
$errors_a[] = 'the filter needs some input';
}
}
if (!empty($input_a)){
if ($filter_a == 0){
$errors_a[] = 'filter is not activated';
}
}
if there is no error and both criteria are fulfilled the filter either is on or not.
so the logical behind that is, when loading the page the checkbox have to be unchecked. after regarding the criteria to filter it is on.
to display the status checked or unchecked under the conditions below it should be checked after submit or either not. therefor i have this code for each filter (respective checkbox_filter_b, ...) the part of the checkbox after the inputfield:
<?php
if (checkbox_filter_a == 0 ) {
echo '<input type="checkbox" name="checkbox_filter_a" value="1" checked/>';
}else {
echo '<input type="checkbox" name="checkbox_filter_a" value="1"/>';
}
?>
what does not satisfy at all. this is because of the following problem:
when loading the page it will show all checkboxes are unchecked. if i try to cause an error because of no filled input or just checked checkbox for one of these filters, after submit all other checkboxes are automatically checked.
so if there is someone who could help me out i really would appreciate. thanks a lot.

Answer 1

Perhaps you could do it this way, by defining default values for your check boxes and values at the start of your script. Then change them with the values of the POSTed if there set or not.
<?php
//Setup Variable Defaults, if POST dont change them then there no complicated ifelse's
$filter_a=null;
$checkbox_filter_a='<input type="checkbox" name="checkbox_filter_a" value="1"/>';
$filter_b=null;
$checkbox_filter_b='<input type="checkbox" name="checkbox_filter_b" value="1"/>';
$filter_c=null;
$checkbox_filter_c='<input type="checkbox" name="checkbox_filter_c" value="1"/>';
//Check for post
if($_SERVER['REQUEST_METHOD'] == 'POST'){
//If the check box is not checked checkbox_filter_a will fail this part
// so $filter_a will still be null
if(isset($_POST['filter_a']) && isset($_POST['checkbox_filter_a'])){
$filter_a = trim($_POST['filter_a']);
$checkbox_filter_a ='<input type="checkbox" name="checkbox_filter_a" value="1" checked/>';
}
if(isset($_POST['filter_b']) && isset($_POST['checkbox_filter_b'])){
$filter_b = trim($_POST['filter_b']);
$checkbox_filter_b = '<input type="checkbox" name="checkbox_filter_b" value="1" checked/>';
}
if(isset($_POST['filter_c']) && isset($_POST['checkbox_filter_c'])){
$filter_c = trim($_POST['filter_c']);
$checkbox_filter_c = '<input type="checkbox" name="checkbox_filter_c" value="1" checked/>';
}
}
echo <<<FORM
<form method="POST" action="">
<p>Inputfield a: <input type="text" name="filter_a" value="$filter_a" size="20"> filter for a: on/off:$checkbox_filter_a</p>
<p>Inputfield b: <input type="text" name="filter_b" value="$filter_b" size="20"> filter for b: on/off:$checkbox_filter_b</p>
<p>Inputfield c: <input type="text" name="filter_c" value="$filter_c" size="20"> filter for c: on/off:$checkbox_filter_c</p>
<p><input type="submit" value="Submit"></p>
</form>
FORM;
//now here all you have to do is see if these values are not null and build your query
echo $filter_a.'<br />';
echo $filter_b.'<br />';
echo $filter_c.'<br />';
?>