Aggregate returns empty array

Question

Using mongoose's Model.aggregate() returns an empty array.

I've essentially copied the format as seen here.

var match = {};
var project = {};
    project["_id"] = 0;
    project["products.totalprice"] = 1;
    project["line"] = "$products.closedate";

ThisCollection.aggregate([
    {$match: match},
    {$project: project},
    {$group: {
        _id: "$line"
    }}

], function(err, docs){
    console.log(docs); //!! Returning []
});

My schema is essentially a name and _id field with a nested array of products with totalprice, closedate and some other fields.

There are most certainly a plethora of entries (some 130,000 records). Can anyone spot an issue with this?

Does the query without the $group statement return any results ? — Alex
– Alex, Commented Nov 12, 2015 at 22:47
@Jaco Nope, tried that still empty. Checking over my keys again, but the " missing was a typo on the copy-paste. — Randy Hall
– Randy Hall, Commented Nov 12, 2015 at 22:53
@Jaco Almost... Using $products.totalprice in the project object, I'm now getting undefined for docs. — Randy Hall
– Randy Hall, Commented Nov 12, 2015 at 23:05
@Jaco Hold the phone... might be something wrong with my data. Give me a moment. — Randy Hall
– Randy Hall, Commented Nov 12, 2015 at 23:07

Alex · Accepted Answer · 2015-11-12 23:08:53Z

1

I have created this dummy data to represent a skeleton of your schema:

db.data.save({name:"a",products:{totalprice:1,closedate:1}})
db.data.save({name:"b",products:{totalprice:2,closedate:2}})

This query does return two records and is identical to yours when inserting the JSON string for the JavaScript variable project

ThisCollection.aggregate([{$match:{}},{$project:{"_id":0,"products.totalprice":1,line:"$products.closedate"}},{$group:{_id:"$line"}}])

edited Nov 12, 2015 at 23:08

answered Nov 12, 2015 at 22:50

Alex

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2 Comments

Randy Hall Over a year ago

My collection was empty.

Alex Over a year ago

Yes, that doesn't help:-)

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