I'm learning about map-reduce functionality of mongodb. My first tests doesn't work as I expected and I want to know how is it working.
Is there any way to write to mongodb console from javascript functions so I can inspect it?
I tried console.log("...") but it doesn't work.
I will ask later about my tests if there isn't any way to do it.
You have to use 'print( "anything .." )' or printjson to display objects.
andrey@andrey:~$ mongo
MongoDB shell version: 2.0.2
connecting to: test
> object = { "name" : "any name .." , "key" : "value" }
{ "name" : "any name ..", "key" : "value" }
> printjson ( object )
{ "name" : "any name ..", "key" : "value" }
> print ( "hello world" )
hello world
>
I guess from map/reduce functions you need to insert your debug messages into some logs collection:
var map = function() {
//some staff here
};
var reduce = function(key, values) {
db.mr_logs.insert({message: "Message from reduce function"});
//some staff here
};
res = db.items.mapReduce(map, reduce,{ query : {}, out : 'example1' })
After this you can find your debug results in mr_logs collection.
db.mr_logs.find();
As for print it seems not printing output to console when you are in map or reduce functions.
there is a super easy workaround in map-reduce environment.
You can just write the name of the function / object like so:
>fn = function (){return12;}
>fn
function (){return12;}
>
Try it here: http://try.mongodb.org/
