Map Reduce Mongodb Node JS native driver
I'm working with the Mongodb native driver using a Map reduce function. Basically I have a mediaId as a key and want to count how many medias loaded and started per mediaId. So what I've done was:
var map = function(){
emit(this.media.id, {
count: 1,
played: 0,
ph: this.project.id,
title: this.media.title,
media: this.media.id,
origin: this.origin,
thumbnail: this.media.thumbnail,
mediaDuration: this.media.mediaDuration,
state: this.state
});
};
var reduce = function(k, vals) {
result = {
count: 0,
played: 0,
ph: '',
title: '',
media: '',
origin: '',
thumbnail: '',
mediaDuration: 0,
sta开发者_StackOverflowte: ''
};
vals.forEach(function(doc){
result.count += doc.count;
result.ph = doc.ph;
result.title = doc.title;
result.media = doc.media;
result.thumbnail = doc.thumbnail;
result.mediaDuration = doc.mediaDuration;
result.state = doc.state;
result.origin = doc.origin;
if(doc.state === "started") {
result.played += 1;
}
});
return result;
};
In my test collection I have 2 different mediaIds. One with 553 objects and another one with just 1 object. I've putted all in the "started" state to test this so basically the number of count should be equal to the number of played. When I run the Map/Reduce function it returns to me ( I used the "toArray" function of the mongodb native driver):
[ { _id: '12398asdsa9802193810asd120',
value:
{ count: 1,
played: 0,
ph: '123213ased12231',
title: 'xxxxxxxxxxxxxxxxxxxxxxxxxxx',
media: '1xxxxxxxxxxxxxxxxxxxxxxxxxxx1',
origin: 'http://www.google.com',
thumbnail: 'http://cache.ohinternet.com/images/0/0e/Forever_Alone.png',
mediaDuration: 12321321,
state: 'started' } },
{ _id: '2c9f94b42f5b5114012f5b92ea430066',
value:
{ count: 553,
played: 155,
ph: '316',
title: 'xxxxxxxxxxxxxxxxxxxxxxxxxxx',
media: '2xxxxxxxxxxxxxxxxxxxxxxxxxxx2',
origin: 'http://localhost:9000/views/index.html',
thumbnail: null,
mediaDuration: null,
state: 'started' } } ]
It seems that one I have just one object the reduce function isn't called ( I did some tests with another collection with more than 100 mediaIds and the behavior was identical. Does anyone have an idea of what is wrong with that?
Thanks A LOT for your time, Cheers.
I sort of solved the "issue". I did the filter on the Map Function and not on the Reduce function. Something like this:
var map = function(){
if(this.media.state==="started") {
var played = 1;
}else{var played = 0;}
emit(this.media.id, {
count: 1,
played: played,
ph: this.project.id,
title: this.media.title,
media: this.media.id,
origin: this.origin,
thumbnail: this.media.thumbnail,
mediaDuration: this.media.mediaDuration,
state: this.state
});
};
Hope it helps anyone that is having the same "problem"
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