I am getting an issue for running the following aggregate query:
db.snippets.aggregate([ { '$project': { month: { '$month': '$created_at' }} } ]) The error message for the same is:
assert: command failed: { "errmsg" : "exception: can't convert from BSON type EOO to Date", "code" : 16006, "ok" : 0 } : aggregate failed How do i get around this issue. I found a related question
Related Stack Overflow question
But it doesnt tell how to get things done.
You likely have one or more docs with a created_at value that's not a BSON Date and you'll need to fix that by converting those values to Date or removing them.
You can find those docs with a $not query that uses the $type operator like:
db.snippets.find({created_at: {$not: {$type: 9}}}) If the created_at values are date strings, you can find the docs that need updating and then update them in the shell using code like:
db.snippets.find({created_at: {$not: {$type: 9}}}).forEach(function(doc) { // Convert created_at to a Date doc.created_at = new Date(doc.created_at); db.snippets.save(doc); }) In some situations, some documents are supposed to have empty Date fields. In those cases, you could try this (using your example):
db.snippets.aggregate([ { '$project': { month: { $cond: [{ $ifNull: ['$created_at', 0] }, { $month: '$created_at' }, -1] }} } ]) In this example, we would get -1 in the cases whenever no field '$created_at' is found. For all the other cases, we would get the Date month.
I had a related issue, but in my case the Date fields were the members of an array, so the error was "can't convert BSON type Object to Date".
I needed to get the day of week from the dates in the possibleTripDateTimes array.
Sample document:
{ "possibleTripDateTimes" : [ { "tripDateTime" : ISODate("2015-08-01T06:00:00.000-0700") } ] } The fix was simply to use dot notation to address the array member fields.
db.trips.aggregate([ { $project: { departTime: { $map: { input: "$possibleTripDateTimes.tripDateTime", as: "dateTime", in: { $dayOfWeek: "$$dateTime" } } } } } ] ); I hope this helps someone who also gets zero search results on the "BSON type Object" search
try this one, its help for me above problem.
db.snippets.aggregate([{ '$project': { month: { $substr: ["$created_at", 5, 2] } } }]); above code get month wise
data is entered into the database in ISO format which can then be easily worked with.
I had the same problem, I figured that the date field is missing for some of the documents causing the conversion to fail. I just added a match clause to filter these out. But ofcourse i am investigating on my app side why they are not being populated.
db.snippets.aggregate([ { '$match': { 'created_at': { "$exists": true } } }, { '$project': { month: { '$month': '$created_at' } } } ]) This error can also appear if you have incorrectly named your properties in your aggregation relative to what they are in your database.
For example my code was
$group: { _id: {$week: "$projects.timeStamp"}, total: { $sum: "$projects.hours" } } But I hadn't camelcased timestamp in my database so simply modifying to projects.timestamp fixed it.
I had a similar problem, and solved it checking if the date existed.
db.users.aggregate([ {$project:{day: { $cond: ["$bd", { $dayOfMonth: "$bd" }, -1] }, month: { $cond: ["$bd", { $month: "$bd" }, -1] }, year: { $cond: ["$bd", { $year: "$bd" }, -1] } }}, {$match:{"month":1, "day":15}} ]) My date field is bd and with that match I'm getting all users that have their birthday on January 15th.