June 2014
Intermediate to advanced
696 pages
38h 52m
English
Content preview from Node.js, MongoDB, and AngularJS Web DevelopmentBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Using Aggregation Framework Operators
MongoDB’s aggregation framework is extremely powerful in that it allows you to pipe the results of one aggregation operator into another multiple times. This data set shows an example:
{o_id:"A", value:50, type:"X"}{o_id:"A", value:75, type:"X"}{o_id:"B", value:80, type:"X"}{o_id:"C", value:45, type:"Y"}
The following aggregation operator set would pipeline the results of the $match into the $group operator and then return the grouped set in the results parameter of the callback function. Notice that when referencing the values of fields in documents, the fieldname is prefixed by a dollar sign—for example, $o_id and $value. This syntax tells the aggregate framework to treat it ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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