mongodb javascript queries

Question

currently I'm working on a project in Java, and I need to run the JavaScript Mongo queries using Java. I figured out I can do something like that using db.eval(). Problem is I have the following JavaScript query for Mongo and I have no idea how can I pass the whole script to the db.eval() method.

var red = function(doc, out) {
out.count_order++;
out.sum_qty += doc.quantity;
out.sum_base_price += doc.extendedprice;
out.sum_disc_price += doc.extendedprice * (1 - doc.discount);
out.sum_charge += doc.extendedprice * (1 - doc.discount) * (1 + doc.tax);
out.avg_disc += doc.discount 
};
var avg = function(out) {
out.avg_qty = out.sum_qty / out.count_order;
out.avg_price = out.sum_base_price / out.count_order;
out.avg_disc = out.avg_disc / out.count_order 
};
db.deals.group( {
key : { RETURNFLAG : true, LINESTATUS : true},
cond : { "SHIPDATE" : {$lte: new Date(1998, 8, 1)}},
initial: { count_order : 0, sum_qty : 0, sum_base_price : 0, sum_disc_price : 0,
sum_charge : 0, avg_disc : 0},
reduce : red,
finalize : avg
});

I haven't worked with MongoDB but I guess you can put this String in a StringBuilder and send it to your db.eval() method. — Luiggi Mendoza
– Luiggi Mendoza, Commented Apr 26, 2013 at 15:54

ACE · Accepted Answer · 2013-04-26 16:19:25Z

1

I encourage you to look at the mongodb java driver to run queries from Java. The Java driver allows one to interact with their mongodb database directly in Java. Thus, you can just port this code to Java and do it all in Java, avoiding ever having to use javascript or db.eval. Let me know if you would like more clarification.

answered Apr 26, 2013 at 16:19

ACE

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Abhishek Kumar · Accepted Answer · 2013-04-30 18:34:39Z

0

you can also use stored procedures in which you can call the stored functions from the java-driver using eval()

Some details : http://dirolf.com/2010/04/05/stored-javascript-in-mongodb-and-pymongo.html

Recently in v2.4 there were some concurrency improvements for javascript operations : http://docs.mongodb.org/manual/release-notes/2.4-javascript/

answered Apr 30, 2013 at 18:34

Abhishek Kumar

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