Question

Background: Using CodeIgniter with this MongoDB library.

This is my first go-round with mongodb and I’m enjoying it thus far. It’s taken a while for me to separate myself from the sql way of thinking, but it is a perfect fit for my current project.

I’m trying to push an array into a document using…

$this->mongo_db->where(array('_id'=>$estimate_id))->push("measurements", $newData)->update('estimates');

If I encode $newData using json_encode($newData) I get {"levels":[{"level_qty":12,"level_uom":"ft"}]}

The problem is, when my function creates the measurements line in the mongodb document, it automatically starts an array with my insertion at [0]. Like this…

"measurements" : [ { "levels" : [ { "level_qty" : 12, "level_uom" : "ft" } ] }]

…leaving me with…

-measurements
--0
----levels
-----0
------level_qty => 2,
------level_uom => ft

What I really want is…

-measurements
--levels
---0
----level_qty => 2,
----level_uom => ft

I’m certain I’m missing something fairly elementary (i.e. php related & not mongodb related), but I’m an admitted amateur who has waded too deep.

Answer 1

$push is used to append a value to an array. In your example, measurements is an array and Mongo is appending $newData as its first element. This explains the 0 index between measurements and levels. In your desired result, measurements is an object equivalent to $newData (i.e. it has a levels property, which in turn has an array of objects within).

Either of the following examples should accomplish what you want:

// if $newData is {"levels": [{"level_qty":12,"level_uom":"ft"}]}
->set("measurements", $newData)

// if $newData is [{"level_qty":12,"level_uom":"ft"}]
->set("measurements.levels", $newData)

// if $newData is {"level_qty":12,"level_uom":"ft"}
->push("measurements.levels", $newData)

Note: $push is going to be more flexible if you want to append data with future updates, whereas $set will naturally overwrite the given field.