Pre-populating and compare select field with 'selected' option - php

Question

I am pulling form data from home.php into results.php and using $_GET['xxxxx'] to pre-populate fields of another form. I can populate input fields okay, but how would you compare an option field and $sale_type to selected if equal?
home.php
<form action="results.php" method="GET">
<input id="address" name="address" type="text" class="form-control1"/>
<select type="text" name="sale_type" placeholder="Sale Type">
<option value="Sale">For Sale</option>
<option value="Rent">To Rent</option>
</select>
<input name="submit" type="SUBMIT" value="Next" class="form-control1">
</form>
results.php
Option fields are already populated to ensure the form will work if it's used without results from home.php. I need to compare $sale_type value with the option of name="sale_type and if equal change that option value to selected.
$address = $_GET['address'];
$sale_type = $_GET['sale_type']; ?>
<form method="POST">
<input id="address" name="address" type="text" value='<?php echo $address; ?>'>
<select type="text" name="sale_type" placeholder="Sale Type">
<option value="Sale">For Sale</option>
<option value="Rent">To Rent</option>
</select>
<button type="submit" id="filter">Search</button>
<input type="hidden" name="action" value="ek_search">
</form>
What I'd like results to do
$address = $_GET['address'];
$sale_type = $_GET['sale_type']; ?> //If value is Sale
<form method="POST">
<input id="address" name="address" type="text" value='<?php echo $address; ?>'>
<select type="text" name="sale_type" placeholder="Sale Type">
<option value="Sale" selected>For Sale</option> //Change to selected if equal
<option value="Rent">To Rent</option>
</select>
<button type="submit" id="filter">Search</button>
<input type="hidden" name="action" value="ek_search">
</form>

Answer 1

You could check and then marked as selected when condition satisfy. One of the example is :
<option value="Sale" <?php if(condition) echo "selected" ?> >For Sale</option>

Answer 2

You'd compare the variable to value in the option tag like so:
<option value="Sale" <?= ($sale_type === 'Sale') ? 'selected' : ''; ?>>For Sale</option>
Another, option, if you will, is to set an array of sale_types. Instead of checking each individual option value, you could loop through the options and check there. Like this:
$sale_types = [
'Sale' => 'For Sale',
'Rent' => 'To Rent',
'SomeOtherType' => 'Something Else'
];
Then in select element:
<? foreach ($sale_types as $sale_value => $sale_option): ?>
<option value="<?= $sale_option; ?>" <?= ($sale_type === $sale_option) ? 'selected' : ''; ?>><?= $sale_value; ?></option>
<? endforeach; ?>

Answer 3

If you're going to do very much of this at all, my recommendation is to build a PHP function. Otherwise, you end up with a bunch of mixed HTML / PHP to check conditions.
This allows you to set up and display a dropdown quickly any time you need to.
Something like this would do what you want and would be re-usable:
// Function to generate the HTML for a select
function dropdown_array( $name, $value, $array, $placeholder = '' ) {
$temp_input = '<select name="' . $name . '"';
$temp_input .= ( $placeholder ) ? ' placeholder="' . $placeholder . '"' : '';
$temp_input .= '>' . PHP_EOL;
if ( is_array( $array ) ) {
foreach ( $array as $val => $text ) {
$temp_input .= '<option value="' . $val . '"';
if ( $value === $val ) {
$temp_input .= ' selected';
}
$temp_input .= '>' . $text . '</option>' . PHP_EOL;
}
}
$temp_input .= '</select>' . PHP_EOL;
return $temp_input;
}
Then, in your situation, usage would look like so:
$array = array( 'Sale' => 'For Sale', 'Rent' => 'To Rent' );
echo dropdown_array( 'sale_type', $sale_type, $array, 'Sale Type' );