search-with-pre-get-posts.php

<?php
if ( ! isset( $_SESSION ) )
    session_start();

function pxjn_init_session_variables() {
	
	if( ! isset( $_SESSION[ 'pxjn_wpac_job_category' ] ) )
		$_SESSION[ 'pxjn_wpac_job_category' ] = 'zero';
	
	if( ! isset( $_SESSION[ 'pxjn_wpac_job_location' ] ) )
		$_SESSION[ 'pxjn_wpac_job_location' ] = 'zero';
		
	if( ! isset( $_SESSION[ 'pxjn_wpac_job_type' ] ) )
		$_SESSION[ 'pxjn_wpac_job_type' ] = 'zero';
	
}

add_action( 'init', 'pxjn_init_session_variables', 10 );

function pxjn_init_job_search_form() {
	
	/* check form is submitted */
	if( $_POST[ 'pxjn_search_form_used' ] == 'yes' ) {
		
		if( isset( $_POST[ 'pxjn_wpac_job_category' ] ) )
			$_SESSION[ 'pxjn_wpac_job_category' ] = (int) $_POST[ 'pxjn_wpac_job_category' ];
		
		if( isset( $_POST[ 'pxjn_wpac_job_location' ] ) )
			$_SESSION[ 'pxjn_wpac_job_location' ] = (int) $_POST[ 'pxjn_wpac_job_location' ];
		
		if( isset( $_POST[ 'vwpac_job_type' ] ) )
			$_SESSION[ 'pxjn_wpac_job_type' ] = (int) $_POST[ 'pxjn_wpac_job_type' ];
		
	}
	
}

add_action( 'init', 'pxjn_init_job_search_form', 20 );

function pxjn_job_search_alter_query( $query ) {
	
	if( ! $query->is_main_query() || is_admin() || ! $query->is_post_type_archive( 'wpac_job' ) )
		return;
	
	/* setup a tax query array to store our tax queries in including an and relation to add tax_queries together */
	$pxjn_tax_query = array( 'relation' => 'AND' );

	/* setup an array to store our meta queries in */
	$pxjn_meta_query = array();
	
	/* check if user has chosen a job category to search within */
	if( $_SESSION[ 'pxjn_wpac_job_category' ] != 'zero' ) {

		$pxjn_tax_query[] = array(
            'taxonomy' => 'wpac_job_category',
            'field' => 'id',
            'terms' => (int) $_SESSION[ 'pxjn_wpac_job_category' ]
	    );

	} // end if have job cat set

	/* check if user has chosen a job location to search within */
	if( $_SESSION[ 'pxjn_wpac_job_location' ] != 'zero' ) {

		$pxjn_tax_query[] = array(
            'taxonomy' => 'wpac_job_location',
            'field' => 'id',
            'terms' => (int) $_SESSION[ 'pxjn_wpac_job_location' ]
	    );

	} // end if have job location set
	
	/* check if user has chosen a job type to search within */
	if( $_SESSION[ 'pxjn_wpac_job_type' ] != 'zero' ) {

		$pxjn_tax_query[] = array(
            'taxonomy' => 'wpac_job_type',
            'field' => 'id',
            'terms' => (int) $_SESSION[ 'pxjn_wpac_job_type' ]
	    );

	} // end if have job type set

	/* check whether we should be running a tax_query */
	if( ! empty( $pxjn_tax_query ) ) {

		$query->set( 'tax_query', $pxjn_tax_query );

	} // end if need tax query

	return;

}

add_action( 'pre_get_posts', 'pxjn_job_search_alter_query' );