Wordpress - Update post by meta information - php

Question

I'm looking for a solution, where I can update posts by meta information and not by id.
I got my content from an external resource via jsonp. I save the content into the database.
The only way I have found is, to update a post by id - but I have no id. What I have, is an article ID from the other resource. I save this article id to every wp post as meta information.
So, is there any way, to update a post by it's meta information?

Answer 1

Ok,
here is some code and what I have done right now:
public function saveArticleInWpDatabase($json_data){
for ($i = 0; $i < count($json_data); $i++) {
$articleId = $json_data[$i]['articleId'];
$img = $json_data[$i]['img'];
$articleHeadline = $json_data[$i]['articleContent']['headline'];
$articleContent = $json_data[$i]['articleContent']['content'];
$termsInput = $json_data[$i]['articleContent']['terms'];
$terms = explode(',',$termsInput);
$creationDate = $json_data[$i]['articleCreationDate'];
$modifiedDate = $json_data[$i]['articleModifiedDate'];
//Check if post with article ID in postmeta exists
$existingId = $this->wpdb->get_var("SELECT post_id FROM ".$this->wpdb->postmeta." WHERE (meta_key = 'article_id' AND meta_value = '".$articleId."')");
//Posts doesn't exist
if ($existingId == null) {
$my_post = array(
'post_date' => $creationDate,
'post_modified' => $modifiedDate,
'post_title' => $articleHeadline,
'post_content' => $articleContent,
'post_status' => 'publish',
'post_author' => 1,
'post_category' => array(0, $categoryId)
);
$last_id = wp_insert_post($my_post);
add_post_meta($last_id, 'article_id', $articleId, true);
wp_set_post_categories($last_id, array(0,$categoryId), true);
wp_set_post_terms( $last_id,$terms, 'post_tag', true );
//$this->_import_photo($last_id, $img);
}
//Post exists
else{
$my_post = array(
'ID' => $existingId,
'post_date' => $creationDate,
'post_modified' => $modifiedDate,
'post_title' => $articleHeadline,
'post_content' => $articleContent,
'post_status' => 'publish',
'post_author' => 1,
'post_category' => array(0, $categoryId)
);
//Get last modified date and compare it with the new one
$lastUpdate = $this->wpdb->get_var("SELECT post_modified FROM " . $this->wpdb->posts . " WHERE ID = ".$existingId);
if(strcmp($lastUpdate, $modifiedDate) != 0){
var_dump("Update article with id: " . $existingId);
$last_id = wp_update_post($my_post);
}
else{
var_dump("Article: " . $existingId . " Nothing changed");
}
}
}
}
As you can see, I save the unique article number from the other CMS if the article doesn't exists.
If the article with the meta_key: article_id and the current value exist, I check if the modified date is the same or not. If not, I will update the posts.
I call this function via a unix cron job every minute. But I think, that this is not the best way (performance)(too many db requests?).
The other think is, that the post_modified value is always the same as post_date, but I got two different values in my json.
e.g.
"articleCreationDate": "2012-05-21 14:38:29", "articleModifiedDate": "2016-02-11 14:52:01"
But it only saved the articleCreationDate in both columns(post_date, post_modified).
So, did anyone has a better solution or idea? And did anyone know, why it doesn't save the modified date value from my json?
Cheers