You can set the values with the filter wpcf7_form_tag and add the shortcode attributes with the filter shortcode_atts_wpcf7
add_filter("wpcf7_form_tag", function($scanned_tag, $replace){
if ("press_post" === $scanned_tag["name"]) {
$contact_form = WPCF7_ContactForm::get_current();
$number_of_posts = $contact_form->shortcode_attr("number_of_posts");
$post_type = $contact_form->shortcode_attr("post_type");
// using $number_of_posts and $post_type here
$scanned_tag['raw_values'] = [
"number_of_posts \"$number_of_posts\" - post_type \"$post_type\" | val 1",
"Test 2|val 2",
"Test 3|val 3",
];
$pipes = new WPCF7_Pipes($scanned_tag['raw_values']);
$scanned_tag['values'] = $pipes->collect_befores();
$scanned_tag['pipes'] = $pipes;
}
return $scanned_tag;
}, 10, 2);
add_filter("shortcode_atts_wpcf7", function ($out, $pairs, $atts, $shortcode) {
foreach (["number_of_posts", "post_type"] as $a) {
if (isset($atts[$a])) {
$out[$a] = $atts[$a];
}
}
return $out;
}, 10, 4);
there is always “Test 2” in the HTML code but CF7 replace the value with “val 2” in the e-mail.