PHP mongodb update - $push array into array

Question

I'm trying to update the "coordinates" property in the Mongo document with new events. ie. Merge the "coordinates" array (contains array of events) with new array of events.

What I have so far :

$update = array('$push' => array("coordinates" => $events));
/** @var \MongoCollection $collection */
$collection = $db->$collectionName;
$return = $collection->update($conditions, $update, $options);
if ($return === false) {
 throw new \ErrorException('Unable to update collection');
}

This works without throwing any error but not as intended. The above query appends the $events array to the "coordinates" array as an array.

Confusing? Maybe the image below will explain better..

enter image description here

Maybe someone can help me figure where I'm going wrong!

• Shalom Sam: I know of one solution so far .i.e offloading the merge in php using array_merge() and then rewrite the "coordinates" with $set. But this doesn't seem like the best solution to me.

Answer 1

You need to use the $each operator

$update = array('$push' => array("coordinates" => array('$each' => $events)));
$return = $collection->update($conditions, $update, $options)

• Shalom Sam: Ahh!! .. So that was what I was missing! Thanks a ton! :)
• Sede: @ShalomSam Glad to have been of help!
• Shalom Sam: just another question out of curiosity @user3100115 - does $each actually run some sort of foreach loop inside mongodb? If so i wonder which is more expensive, $each or array_merge()
• Sede: Using array_merge() is more expensive because $each appends each element to your array and is a native API so faster.