I am trying post submit on front end. All works without thumbnail uploading and setting. Here is my html form.

<form method="post" action="">
    <input type="text" name="title">
    <textarea name="content"></textarea>
    <input type="file" name="thumbnail">
    <input type="submit" name="submit">
</form>

And here is my php code.

<?php
if (isset($_POST['submit'])) {

    global $wpdb;
    require_once ABSPATH . 'wp-admin/includes/image.php';
    require_once ABSPATH . 'wp-admin/includes/file.php';
    require_once ABSPATH . 'wp-admin/includes/media.php';

    $title   = $_POST['title'];
    $content = $_POST['content'];

    # Set Post

    $new_post = array(
        'post_title'    => $title,
        'post_content'  => $content,
        'post_status'   => 'pending',
        'post_type'     => 'post',
    );

    $post_id = wp_insert_post($new_post);

    # Set Thumbnail

    $args = array(
        'post_type' => 'attachment',
        'posts_per_page' => -1,
        'post_status' => 'pending',
        'post_parent' => $post_id
    );

    $attachments = get_posts($args);

    foreach($attachments as $attachment){
        $attachment_id = media_handle_upload('thumbnail', $attachment->ID);
    }

    if (!is_wp_error($attachment_id)) { 
        set_post_thumbnail($post_id, $attachment_id);
        header("Location: " . $_SERVER['HTTP_REFERER'] . "/?files=uploaded");
    }
}
?>

It creates post ok. But it not sets any thumbnail. I don't know where i am wrong.

I am trying post submit on front end. All works without thumbnail uploading and setting. Here is my html form.

<form method="post" action="">
    <input type="text" name="title">
    <textarea name="content"></textarea>
    <input type="file" name="thumbnail">
    <input type="submit" name="submit">
</form>

And here is my php code.

<?php
if (isset($_POST['submit'])) {

    global $wpdb;
    require_once ABSPATH . 'wp-admin/includes/image.php';
    require_once ABSPATH . 'wp-admin/includes/file.php';
    require_once ABSPATH . 'wp-admin/includes/media.php';

    $title   = $_POST['title'];
    $content = $_POST['content'];

    # Set Post

    $new_post = array(
        'post_title'    => $title,
        'post_content'  => $content,
        'post_status'   => 'pending',
        'post_type'     => 'post',
    );

    $post_id = wp_insert_post($new_post);

    # Set Thumbnail

    $args = array(
        'post_type' => 'attachment',
        'posts_per_page' => -1,
        'post_status' => 'pending',
        'post_parent' => $post_id
    );

    $attachments = get_posts($args);

    foreach($attachments as $attachment){
        $attachment_id = media_handle_upload('thumbnail', $attachment->ID);
    }

    if (!is_wp_error($attachment_id)) { 
        set_post_thumbnail($post_id, $attachment_id);
        header("Location: " . $_SERVER['HTTP_REFERER'] . "/?files=uploaded");
    }
}
?>

It creates post ok. But it not sets any thumbnail. I don't know where i am wrong.

• posts
• uploads
• front-end

• is the media uploaded? Shouldn't media_handle_upload used before the attachment get_posts? Not sure the attachment get_posts query is needed at all. – Stefano Tombolini Commented Feb 17, 2018 at 16:02
• No. Media not uploading. Do you have any suggestion? – wpdev Commented Feb 17, 2018 at 16:24
• Check the answer I proposed. – Stefano Tombolini Commented Feb 17, 2018 at 16:47

3 Answers 3

In form, you need the code enctype="multipart/form-data"

<form method="post" action="" enctype="multipart/form-data">

You can use the exemple provided by the wp_insert_attachment() function codex page and the set_post_thumbnail() too :

$file = $_FILES['thumbnail']['tmp_name'];

/*
 * $filename is the path to your uploaded file (for example as set in the $_FILE posted file array)
 * $file is the name of the file
 * first we need to upload the file into the wp upload folder.
 */
$upload_file = wp_upload_bits( $filename, null, @file_get_contents( $file ) );
if ( ! $upload_file['error'] ) { 
    // Check the type of file. We'll use this as the 'post_mime_type'.
    $filetype = wp_check_filetype( $filename, null );

    // Get the path to the upload directory.
    $wp_upload_dir = wp_upload_dir();

    // Prepare an array of post data for the attachment.
    $attachment = array( 
        'post_mime_type' => $filetype['type'],
        'post_title'     => preg_replace( '/\.[^.]+$/', '', $filename ),
        'post_content'   => '',
        'post_status'    => 'inherit',
        'post_parent'    => $post_id
    );

    // Insert the attachment.
    $attach_id = wp_insert_attachment( $attachment, $upload_file['file'], $post_id );

    if ( ! is_wp_error( $attachment_id ) ) { 
        // Make sure that this file is included, as wp_generate_attachment_metadata() depends on it.
        require_once( ABSPATH . 'wp-admin/includes/image.php' );

        // Generate the metadata for the attachment, and update the database record.
        $attach_data = wp_generate_attachment_metadata( $attach_id, $upload_file['file'] );
        wp_update_attachment_metadata( $attach_id, $attach_data );

        set_post_thumbnail( $post_id, $attach_id );
    }
}

There seem to be some unnecessary code. Try the following one:

$title   = $_POST['title'];
$content = $_POST['content'];

# Set Post

    $new_post = array(
        'post_title'    => $title,
        'post_content'  => $content,
        'post_status'   => 'pending',
        'post_type'     => 'post',
    );

    $post_id = wp_insert_post($new_post);

    # Set Thumbnail

  require_once(ABSPATH . "wp-admin" . '/includes/image.php');
  require_once(ABSPATH . "wp-admin" . '/includes/file.php');
  require_once(ABSPATH . "wp-admin" . '/includes/media.php');

$attachment_id = media_handle_upload('thumbnail', $post_id);

if (!is_wp_error($attachment_id)) { 
        set_post_thumbnail($post_id, $attachment_id);
        header("Location: " . $_SERVER['HTTP_REFERER'] . "/?files=uploaded");
    }

More info (see nonces for security too): https://codex.wordpress/Function_Reference/media_handle_upload