Where does the uploaded image go?

Question

add_action( 'customize_register', 'boilerplate_customize_register' );
function boilerplate_customize_register($wp_customize) {
    $wp_customize->add_section( 'themename_color_scheme', array(
        'title'          => __( 'Color Scheme (sect!on name)', 'themename' ),
        'description'    => "This changes color scheme",
        'priority'       => 135,
    ));
    $wp_customize->add_setting('themename_theme_options[image_upload_test]', array(
        'default' => 'image.jpg',
        'capability' => 'edit_theme_options',
        'type' => 'option',
    ));
    $wp_customize->add_control( new WP_Customize_Image_Control($wp_customize, 'image_upload_test', array(
        'label' => __('Image Upload Test', 'themename'),
        'section' => 'themename_color_scheme',
        'settings' => 'themename_theme_options[image_upload_test]',
    )));
}

This adds a section in Theme customization page and in it, an image upload dialog. Where does this image go and how can I refer to it?

Answer 1

The theme customiser will take the upload and put it in wp-content, but the folder or specific place is irrelevant. If you find yourself using it, you've made a mistake and your code has gone horribly wrong.

To be specific, your option is not referring to an image you uploaded, it is referring to an Attachment, specifically it saves the ID of an attachment.

Attachments are posts of post type 'attachment', they have post content, post parents, titles etc, and when you use the theme customiser to add an image upload the image gets uploaded, an attachment post will be created for it, and the ID of that attachment is then used to refer to the image. The ID is saved as a theme mod.

You can grab the various sizes of the attachment using functions such as wp_get_attachment_url

You can read more about this here:

http://codex.wordpress.org/Function_Reference/wp_get_attachment_url

You'll also find the function get_theme_mod useful:

http://codex.wordpress.org/Function_Reference/get_theme_mod

Answer 2

By default it goes into "wp-content/uploads" and possibly into date organized folders depending on how your site is configured. It is possible to change the default location and it is possible to conditionally change the location-- that is, change the location only for certain uploads.

All that means that it isn't possible to say with certainty because there are unknowns, but start looking in 'uploads', or just upload an image and "View Source" on the page. You can read the URL from the source easily enough.