Adding a custom picture field to the campaign form

functions.php

<?php
/**
 * This function adds a custom text field to the campaign submission
 * form, as well as the admin campaign editor, campaign emails, and
 * campaign export.
 *
 * Note: This example requires Ambassadors 2+. For an example that worked
 * on previous version, see the link below.
 *
 * @see https://github.com/Charitable/library/blob/master/extensions/ambassadors/legacy/add-text-field.php
 *
 * @return void
 */
add_action( 'init', function( $fields ) {
	$fields = charitable()->campaign_fields();

	// Create the field.
	$field = new Charitable_Campaign_Field(
		'custom_picture_field',
		[
			'label'          => 'Custom Picture Field',
			'data_type'      => 'meta',
			'campaign_form'  => [
				'required' => false,
				'type'     => 'picture',
				'section'  => 'campaign-details',
				'priority' => 30,
			],
			'admin_form'     => [
			   	'type'      => 'content',
				'content'   => '',
				'base_path' => trailingslashit( __DIR__ ),
				'view'      => 'my-custom-picture-field-view',
				'priority'  => 1,
			],
			'show_in_export' => true,
			'email_tag'      => true,
		]
	);

	// Register the field.
	$fields->register_field( $field );
} );

In order to display the picture in the admin, you need to configure the base_path and view arguments in the admin_form setting to correspond to a PHP file

For example, in the example above, the view file would be expected in the same directory where this function is defined, and would be called my-custom-picture-field-view.php.

In the view file, there is a $view_args variable available which is an array. It includes the ID of the uploaded photo with $view_args['value']. You can then display the photo using wp_get_attachment_image():

$photo_id = $view_args['value'];

wp_get_attachment_image( $photo_id );