Concatenate 2D array of binary data

Hi,

I have such a document:

{
	"_id" : ...
	"d" : [
		{
			"h" : [ ]
		},
		{
			"h" : [
				BinData(0,"..."),
				BinData(0,"...")
			]
		}]
}

I want to update all document in a way, that I want to concatenate all binary array elements into 1 binary field, so the “d” property has only 1 BinData() value

Please note, that currently, this is an array of objects, but I think this was a bad design decision

Hi there, any idea regarding this problem?
Thank you