使用php在mongodb中使用索引返回数组项

Question

I want to know how to return array item by using index in mongodb with php:

findOne(array('num[1]' => 'field_id')))

is there a way to do it?

Answer 1

MongoDB has "dot notation" which is a bit different from the JavaScript form because this is not JavaScript:

findOne(array("num.1" => "field_id"))

Noting that array indexes are n-1 per position, so this means the "second" element of the array.

Note that this does not just return "that array item only" and is merely a query to "match" the array item at the position. If you expect only the matched item to return, then you use the positional $ operator and "projection" as well:

findOne(array("num.1" => "field_id"),array( "num.$" => 1))