aggregation-framework

问题 I have the following kind of docs in a collection in mongo db { _id:xx, iddoc:yy, type1:"sometype1", type2:"sometype2", date: { year:2015, month:4, day:29, type:"day" }, count:23 } I would like to do a sum over the field count grouping by iddoc for all docs where: type1 in ["type1A","type1B",...] where type2 in ["type2A","type2B",...] date.year: 2015, date.month: 4, date.type: "day" date.day between 4 and 7 I would like then to sort these sums. I know now how to do this (see this question) db

问题 I have the following kind of docs in a collection in mongo db { _id:xx, iddoc:yy, type1:"sometype1", type2:"sometype2", date: { year:2015, month:4, day:29, type:"day" }, count:23 } I would like to do a sum over the field count grouping by iddoc for all docs where: type1 in ["type1A","type1B",...] where type2 in ["type2A","type2B",...] date.year: 2015, date.month: 4, date.type: "day" date.day between 4 and 7 I would like then to sort these sums. I know now how to do this (see this question) db

问题 Due to recent Mogodb upgrade to 3.6, pentaho kettle mongoinput step aggregation not be able to fetch data from the Mongodb. The error message: com.mongodb.MongoCommandException: Command failed with error 9: 'The 'cursor' option is required, except for aggregate with the explain argument' on server localhost:2915. The full response is { "ok" : 0.0, "errmsg" : "The 'cursor' option is required, except for aggregate with the explain argument", "code" : 9, "codeName" : "FailedToParse" } It seems

问题 I was going thru bunch of mongo docs and can't find a possibility to shuffle or randomize result content is there any ? 回答1: Specifically for the aggregation framework itself there is not really any native way as there is no available operator as yet to do something like generate a random number. So whatever match you could possibly project a field to sort on would not be "truly random" for lack of a shifting seed value. The better approach is to "shuffle" the results as an array after the

问题 I would like to get the result of an aggregation pipeline without the _id filed. I know this is possible if you provide explicitly other fields that will be the output of the projection. But, ¿how can I mimic the $projec in a find call? This is what I want ( No field explicitly included ): db.col.find({},{_id:0}) But in the aggregation framework seems to be impossible: db.col.aggregate([{'$project': {_id:0}}]) Error: Printing Stack Trace at printStackTrace (src/mongo/shell/utils.js:37:15) at

问题 I would like to get the result of an aggregation pipeline without the _id filed. I know this is possible if you provide explicitly other fields that will be the output of the projection. But, ¿how can I mimic the $projec in a find call? This is what I want ( No field explicitly included ): db.col.find({},{_id:0}) But in the aggregation framework seems to be impossible: db.col.aggregate([{'$project': {_id:0}}]) Error: Printing Stack Trace at printStackTrace (src/mongo/shell/utils.js:37:15) at

问题 I have searched online but could not find any match my case. Here is the situation. I am using aggregate to combine one collection and one document which is from another collection together restaurants.aggregate([ { $match: { _id: { $in: idList } } }, { $lookup: { from: "tags", localField: "details.restaurantType", foreignField: "details.restaurantType._id", as: "types" } }, { $project: { restaurantName: "$details.restaurantName", restaurantType: "$details.restaurantType", type: { $filter: {

问题 I have an aggregation query as follows : db.TWITTER_DATA_Processed.aggregate( {$match : { SpId : 840, Scheduler_id : "SCH_01" }},{$group : {_id : {SpId : "$SpId", Scheduler_id : "$Scheduler_id",Country : "$Country"}, positive_count : { $sum: { $cond: [ { $gt: [ "$Sentiment", 0 ] } , 1, 0 ] } }, neutral_count : { $sum: { $cond: [ { $eq: [ "$Sentiment", 0 ] } , 1, 0 ] } }, negative_count : { $sum: { $cond: [ { $lt: [ "$Sentiment", 0 ] } , 1, 0 ] } }}}) Sample output : { "_id" : { "SpId" : 840,

问题 Using mongodb with NodeJS driver I have 2 collections. One for department and other for students. Sample data for Deparmtent. { "_id" : ObjectId("5a24d20590d3d12155f3094e"), "name" : "CSE", "hod" : "abc", "students" : [ ObjectId("5a2129172c3e542acb78c1f5"), ObjectId("5a2129172c3e542acb78c1f7"), ObjectId("5a2129172c3e542acb78c1f9"), ObjectId("5a2129172c3e542acb78c1fb") ] } { "_id" : ObjectId("5a24d20590d3d12155f3094f"), "name" : "IT", "hod" : "xyz", , "students" : [ ObjectId(

问题 Is it possible to merge array fields in while using MongoDB aggregation framework? Here is a summary problem I am trying to solve: Sample input documents for aggregation: { "Category" : 1, "Messages" : ["Msg1", "Msg2"], "Value" : 1 }, { "Category" : 1, "Messages" : [], "Value" : 10 }, { "Category" : 1, "Messages" : ["Msg1", "Msg3"], "Value" : 100 }, { "Category" : 2, "Messages" : ["Msg4"], "Value" : 1000 }, { "Category" : 2, "Messages" : ["Msg5"], "Value" : 10000 }, { "Category" : 3,