how do i add a value to the top of an array in mongodb?

Question

how do i add a value to the top of an array in mongodb?

say i have this document in my mongo collection:

{ "colors" : [ "red", "green", "blue" ] }

how do i add "yellow" to the front of the list?

when i do:

{$push:{colors:"yellow"}}

i'd get this:

{ "colors" : [ "red", "green", "blue", "yellow" ] }

i want this:

{ "colors" : [ "yellow", "red", "green", "blue"] }

thanks in advance!

Answer 1

For anybody new to this, MongoDB 2.6+ supports the $position operator, which can be used to achieve the desired effect. The benefit here being that you don't need to return your entire document array, update it locally and save it - the $position operator means things can be done atomically.

You need to use it in conjunction with $each:

$push: { colors: { $each: ['yellow'], $position: 0 } }