Using wp_insert_post() and wp_insert_attachment() at the same time - php

Question

I am working on migrate blog posts, which are more than 1000 posts, from an old custom database website to wordpress. After formatted each post with php array, I am testing how to migrate them to wordpress.
What I want to do is migrate blog posts with featured images. After some research, I used wp_insert_post() which worked just with the text contents> However it does not insert featured images, so I need to use wp_insert_attachnment() as well. The problem is when I use wp_insert_post() and wp_insert_attachnment() together, inside foreach loop, it does not work well. The code I have is below. If anyone has knowledge/approach about this issue, please give me advice. Thank you.
$wp_posts = array(
array(
'post_id' => '10',
'post_title' => 'Post Title 1',
'post_date' => '2015-06-22',
'post_content' => 'Post Content 1',
'post_imagePath' => 'http://localhost/test/wp-content/uploads/2016/01/image1.jpg'
),
array(
'post_id' => '11',
'post_title' => 'Post Title 2',
'post_date' => '2015-06-22',
'post_content' => 'Post Content 2',
'post_imagePath' => 'http://localhost/test/wp-content/uploads/2016/01/image2.jpg'
)
);
$filetype['type'] = 'image/jpeg';
$last = count($wp_posts) - 1;
foreach ($wp_posts as $i => $row){
$ID = $row['post_id'];
$title = $row['post_title'];
$content = $row['post_content'];
$postdate = $row['post_date']. " 12:00:00";
$imagePath = $row['post_imagePath'];
if (!get_page_by_title($title, 'OBJECT', 'post') ){
$my_post = array(
'ID' => $ID,
'post_title' => $title,
'post_content' => $content,
'post_date' => $postdate,
);
wp_insert_post( $my_post );
/* wp_insert_attachment */
$filetype = wp_check_filetype( basename( $imagePath ), null );
$wp_upload_dir = wp_upload_dir();
$attachment = array(
'guid' => $wp_upload_dir['url'] . '/' . basename( $imagePath ),
'post_mime_type' => $filetype['type'],
'post_title' => preg_replace( '/\.[^.]+$/', '', basename( $imagePath ) ),
'post_content' => '',
'post_status' => 'inherit'
);
$attach_id = wp_insert_attachment( $attachment, $imagePath, $parent_post_id );
require_once( ABSPATH . 'wp-admin/includes/image.php' );
$attach_data = wp_generate_attachment_metadata( $attach_id, $imagePath );
wp_update_attachment_metadata( $attach_id, $attach_data );
set_post_thumbnail( $parent_post_id, $attach_id );
/* ./wp_insert_attachment */
}
}

Answer 1

Do not add the ID when using wp_insert_post(), this will try and update an entry with that ID.
IMPORTANT: Setting a value for $post['ID'] WILL NOT create a post with
that ID number. Setting this value will cause the function to update
the post with that ID number with the other values specified in $post.
In short, to insert a new post, $post['ID'] must be blank or not set
at all.
wp_insert_post() documentation
Also make sure the post has actually been inserted before continuing your script. eg
$post_id = wp_insert_post( $my_post );
if(!$post_id) {
//log an error or something...
continue;
}

Answer 2

Haven't test it but i think this will do it.
foreach ($wp_posts as $i => $row){
$ID = $row['post_id'];
$title = $row['post_title'];
$content = $row['post_content'];
$postdate = $row['post_date']. " 12:00:00";
$imagePath = $row['post_imagePath'];
$my_post = array(
'ID' => $ID,
'post_title' => $title,
'post_content' => $content,
'post_date' => $postdate,
);
$parent_post_id = wp_insert_post( $my_post ); //Returns the post ID on success.
/**** wp_insert_attachment ****/
$filetype = wp_check_filetype( basename( $imagePath ), null );
$wp_upload_dir = wp_upload_dir();
$attachment = array(
'post_mime_type' => $filetype['type'],
'post_title' => sanitize_file_name(basename($image_url)),
'post_content' => '',
'post_status' => 'inherit'
);
// So here we attach image to its parent's post ID from above
$attach_id = wp_insert_attachment( $attachment, $imagePath, $parent_post_id);
// Attachment has its ID too "$attach_id"
require_once(ABSPATH . 'wp-admin/includes/image.php');
$attach_data = wp_generate_attachment_metadata( $attach_id, $imagePath );
$res1= wp_update_attachment_metadata( $attach_id, $attach_data );
$res2= set_post_thumbnail( $parent_post_id, $attach_id );
}