Gravity Forms: Dynamic creation of fields from CPT

How can I dynamically create set of fields in my Gravity Form, based on my custom post type?

We created a mu-plugin called gravity.php for that:

<?php
/*
* Add fields to Gravity Form
*/

// add fields from CPT 'brochures' to Gravity Form #3
add_filter( 'gform_pre_render_3', 'wpster_add_fields_to_gravity' );
add_filter( 'gform_pre_validation_3', 'wpster_add_fields_to_gravity' );
add_filter( 'gform_pre_submission_3', 'wpster_add_fields_to_gravity' );
add_filter( 'gform_pre_submission_filter_3', 'wpster_add_fields_to_gravity' );
add_filter( 'gform_pre_process_3', 'wpster_add_fields_to_gravity' );

function wpster_add_fields_to_gravity( $form ){

	// get all CPT 'brochures'
	$query = new WP_Query(array(
		'post_type' 			=> 'brochures',
		'post_status'			=> 'publish',
		'posts_per_page' 	=> -1,
		'orderby' 				=> 'title',
		'order' 					=> 'ASC',
	));
	$i = 0;
	while ($query->have_posts()) {
		$query->the_post();
		$brochures[$i]['post_title'] = get_the_title();
		$i++;
	}

	// add CPT to form
	$field_product_id = 200;
	$calculated_formula = "";
	foreach($brochures as $brochure):
		$field_label = $brochure['post_title'];
		$props = array( 
			'id'                => $field_product_id,
			'label' 						=> $field_label,
			'type'              => 'product',
			'inputType'         => 'singleproduct',
			'isRequired'        => false,
			'basePrice'         => 0,
			'enableCalculation' => true,
			'allowsPrepopulate' => true,
			'cssClass' 					=> 'magicForm',
			'inputs'            => [
					0 => [
							'id'    => $field_product_id . '.1',
							'label' => 'Product Name',
							'name'  => 'param_product'
					],
					1 => [
							'id'    => $field_product_id . '.2',
							'label' => 'Price',
							'name'  => 'param_price'
					],
					2 => [
							'id'    => $field_product_id . '.3',
							'label' => 'Quantity',
							'name'  => 'param_qty'
					]
			]
		);
		if (!in_array($field_product_id,array_column($form['fields'], 'id'))) {
			$field = GF_Fields::create( $props );
			array_push( $form['fields'], $field );
			$calculated_formula.= "+{:".$field_product_id.".3}";			
		}
		$field_product_id++;
	endforeach;

	// calculate quantity
	$field_quantity_id = 100;
	$props = array( 
		'id'                => $field_quantity_id,
		'label' 						=> 'Quantity ordered',
		'type'              => 'number',
		'enableCalculation' => true,
		'allowsPrepopulate' => true,
		'calculationFormula' => $calculated_formula,
	);
	if (!in_array($field_quantity_id,array_column($form['fields'], 'id'))) {
		$field = GF_Fields::create( $props );
		array_push( $form['fields'], $field );
	}

	// calculate shipping cost / formula need Gravity Forms Advanced Calculations
	$field_id = 101;
	$calculated_formula = "if( {:".$field_quantity_id."} < 10 ):\n0\n
		elseif( {:".$field_quantity_id."} <= 50 ):\n20\n
		else:\n50\n
		endif;";
	$props = array( 
		'id'                => $field_id,
		'label' 						=> 'Shipping Cost',
		'type'              => 'number',
		'enableCalculation' => true,
		'allowsPrepopulate' => true,
		'calculationFormula' => $calculated_formula,
	);
	if (!in_array($field_id,array_column($form['fields'], 'id'))) {
		$field = GF_Fields::create( $props );
		array_push( $form['fields'], $field );
	}

	// html field
	$field_id = 102;
	$props = array( 
		'id'                => $field_id,
		'label' 						=> 'HTML',
		'type'              => 'html',
		'content'           => '<h3>Frais de port:</h3><10 : CHF0, <=50 : CHF20, au-delà : CHF 50',
	);
	if (!in_array($field_id,array_column($form['fields'], 'id'))) {
		$field = GF_Fields::create( $props );
		array_push( $form['fields'], $field );
	}

	if ( GFForms::get_page() !== 'form_editor' ) {
		return $form;
	}
}
?>