Mongodb insert into existing array

Question

Hey im having issues inserting an element into an existing mongodb document. At the moment there is an array containing a single element in my db :

$count = array();
array_push($count, 0);
$dbase->insert(array("_id"=> $_id,"count"=>$count));

However i now wish to insert a single element back into the "count array" and after looking around this was the recommended way:

 $count=4;
 $dbase->update(array('_id'=>'57b35f7bce23505c10000029'),array('$count'=>$count));

However this is throwing an error (error 500, internal server error) and im unsure why. Iv also tried using insert but it results in the creation of a new document. Any help would be appreciated.

Note you are trying to update $count with the value of the PHP variable $count ... this will not work as you are expecting, see my answer below. — Justin Jenkins
– Justin Jenkins, Commented Aug 19, 2016 at 1:04

Justin Jenkins · Accepted Answer · 2016-08-19 01:02:34Z

1

While I'm not exactly sure why you need an array here, there are a couple ways to update arrays and their members ...

Connect to the database/collection

$m = new MongoClient();
$db = $m->your_database;
$collection = $db->your_colection;

Update one member of the array

If you'd like to update one member of the array (in this case the 0 member) you would do ...

$collection->update(
  array("_id"=> new MongoId("57b6556aa9087c06687ecd7c")),
  array('$set'=>array("count.0"=> 4))
);

Add to the array

If you want to add a new item to the array, your count you can do ...

$collection->update(
  array("_id"=> new MongoId("57b6556aa9087c06687ecd7c")),
  array('$push'=>array("count"=> 4))
);

You would now have two members in the array.

Note: This will only work if count is indeed an array.

Update/change "count" to a number

$collection->update(
  array("_id"=> new MongoId("57b35f7bce23505c10000029")), 
  array('$set'=>array("count"=> 4))
);

This will turn what was an array in a number.

Generally, I'd recommend not using a an array here unless you actually need to store multiple values.

Also, depending on your MongoDB PHP Driver version you may need to use:

new MongoDB\BSON\ObjectID(); instead of new MongoId();

answered Aug 19, 2016 at 1:02

Justin Jenkins

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2 Comments

D3181 Over a year ago

Thanks the one that i meant was your Add to the array solution thanks for clarifying so thoroughly too you cleared up a lot of questions i had about mongodb through php, the documentation seemed to be littered with version for different version of php which made it confusing to find what i was looking for, so thanks again.

Justin Jenkins Over a year ago

@Dean219, no problem! I agree, the official PHP docs are rather confusing & could use some simple, more straight forward examples. :/

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