If Statement Within A Nested Array - php

Question

What I am trying to do is query a WordPress custom post type using meta keys from a search form. The search form takes user inputs and show the results based on the matching criteria, Some of the form's fields might be blank, so I need to make sure I don't pass any blank value to the query argument. I need to use if within the arguments array.
I'll be grateful for any type of help.
This is the code I am using, but getting an error message.
Parse error: syntax error, unexpected T_IF, expecting ')'
Here is my code:
if (isset($POST['stock']) && !empty($POST['stock'])) {
$stock = $POST['stock'];
}
if (isset($POST['mineral']) && !empty($POST['mineral'])) {
$mineral = $POST['mineral'];
}
if (isset($POST['species']) && !empty($POST['species'])) {
$species = $POST['species'];
}
if (isset($POST['color']) && !empty($POST['color'])) {
$color = $POST['color'];
}
if (isset($POST['chemicalclass']) && !empty($POST['chemicalclass'])) {
$chemicalclass = $POST['chemicalclass'];
}
if (isset($POST['locality']) && !empty($POST['locality'])) {
$locality = $POST['locality'];
}
if (isset($POST['description']) && !empty($POST['description'])) {
$description = $POST['description'];
}
if (isset($POST['size']) && !empty($POST['size'])) {
$size = $POST['size'];
}
if (isset($POST['pricegt'])) {
$pricegt = $POST['pricegt'];
} else {
$pricegt = 0;
}
if (isset($POST['pricelt'])) {
$pricelt = $POST['pricelt'];
} else {
$pricelt = 999999;
}
$args = array(
'post_type' => 'products',
'productspecies' => $species,
'localities' => $locality,
'meta_query' => array(
//'relation' => 'OR',
array(
'key' => '_price',
'value' => array( $pricegt, $pricelt ),
'compare' => 'BETWEEN',
'type' => 'numeric',
),
if ($mineral) {
array(
'key' => '_components',
'value' => $mineral,
),
}
if ($stock) {
array(
'key' => '_lotnum',
'value' => $stock,
),
}
if ($color) {
array(
'key' => '_color',
'value' => $color,
),
}
if ($description) {
array(
'key' => '_smalldesc',
'value' => $description,
'compare' => 'LIKE',
),
}
if ($size) {
array(
'key' => '_size',
'value' => $size,
),
}
if ($chemicalclass) {
array(
'key' => '_chemicalclass',
'valeu' => $chemicalclass,
),
}
),
);
?>
<?php $query = new WP_Query( $args ); ?>
<div class="postcount">We Found A Total Of <span><?php echo $query->post_count;?></span> Items Maching Your Search</div>
<?php if ( $query->have_posts() ) : ?>
<?php /* Start the Loop */ ?>
<?php while ( $query->have_posts() ) : $query->the_post(); ?>
What I am doing wrong?

Answer 1

You are trying to pass if statements as arguments to the array() function. PHP does not allow that. One thing you can do is build the array without the optional parts and then add them later if necessary:
if ($stock) {
$args['metaquery'][] = array(
'key' => '_lotnum',
'value' => $stock
);
}

Answer 2

You can't insert instructions in the array initialization code.
Do it this way:
$args = array();
if (something){
$args['metaquery'][] = array(contentsOfTheInnerArray);
}
if (something2){
$args['metaquery'][] = array(contentsOfTheInnerArray2);
}

Answer 3

Not completely sure if this works (in php that is) but you can do something like this:
$array = array(
'price' => isset($POST['pricegt']) ? $POST['pricegt'] : 0,
...
);