MongoDB: can't convert from BSON type EOO to Date

Question

I' trying to use aggregation framework (with ruby) and project the date like this:

db['requests'].aggregate([
{"$project" => {
    _id: 0, 
    method: '$method', 
    user: '$user', 
    year: {'$year' => '$timestamp'}
}}])

the document is like this one:

{
_id: ObjectId("5177d7d7df26358289da7dfd"),
timestamp: ISODate("2013-04-12T03:58:05+00:00"),
method: "POST",
status: "200",
inputsize: "874",
outputsize: "4981",
user: "131"
}

but i get the following error:

Mongo::OperationFailure: Database command 'aggregate' failed: (errmsg: 'exception: can't convert from BSON type EOO to Date'; code: '16006'; ok: '0.0').

This is strange because it works correctly if I run this on the exactly same db which is imported with mongorestore.

Apparently the order of the array passed in to aggregate() is important. If you have fields where something is omitted, you'll want to add that into the $match and have the $match be the first element in the array. I.e. > db.user_account.aggregate( [ { $match : { "uts" : { $exists : true }, "chan_key" : "333261c7a72650a95c68d30cd70" } } , { $project : { "period_month": { $month: "$uts" } } }, { $group: { _id : { "period_month" : "$period_month" }, "number" : { $sum : 1 } } } ] ) — Wedge Martin, Sep 20 '13 at 15:02

score 20 · Accepted Answer · answered Apr 24 '13 at 15:21

20

The problem was that I was saving some documents without the timestamp field.

answered Apr 24 '13 at 15:21

shoen

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27

Yup! Me too. I did a search for documents where my timestamp was 'nil' and there was just one document. I fixed that, and voila! the query works. – Stephen Henderson Aug 11 '14 at 00:02
1

Can you put up an example of how you found such documents. – jsbisht Feb 09 '15 at 17:39

score 2 · Answer 2 · answered Jan 23 '16 at 23:31

If you needed to have some documents without this timestamp field, you could try this (I'm using Javascript/Mongoose notation):

year: { $cond: [{ $ifNull: ['$timestamp', 0] }, { $year: '$deliveryDateEnd' }, -1] }

In this case, every document without the timestamp field would return -1. All the other documents would return the year as expected.

MongoDB: can't convert from BSON type EOO to Date

2 Answers2

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