r - Aggregate by match ObjectId in rmongodb -

i have trouble aggregation involving objectid. pipelines:

{'$match' : {'likes.id' : objectid('50e99acfb35de75402002023')}} {'$project' : {'likes.id' : 1, '_id' : 0}} {'$unwind' : '$likes'} {'$group' : {'_id' : '$likes.id', 'count' : {'$sum':1}}} {'$sort' : {'_id' : 1}} 

my attempt write in r using rmongodb is:

pipe_1 <- mongo.bson.from.json('{"$match" : {"likes.id" : { "$oid" : "50e99acfb35de75402002023" }}}') pipe_2 <- mongo.bson.from.json('{"$project" : {"likes.id" : 1, "_id" : 0}}') pipe_3 <- mongo.bson.from.json('{"$unwind" : "$likes"}') pipe_4 <- mongo.bson.from.json('{"$group" : {"_id" : "$likes.id", "count" : {"$sum":1}}}') pipe_5 <- mongo.bson.from.json('{"$sort" : {"count" : 1}}') pipes <- list(pipe_1,pipe_2,pipe_3,pipe_4,pipe_5) result <- mongo.aggregation(mongo, ns = "analytics.analytics_profiles", pipeline =pipes) 

which returns

mongodb error: 10 

that corresponds bson invalid error code.

i think problem match objectid: first pipeline alone gives same error.

how can fix this?

extra: how can done using mongolite instead?

you should not "dot notation" "array" key in aggregation pipeline, doing still valid. can reduce array elements "id" values $project though:

also looks might need contruct bson matching objectid seperately:

oid <- mongo.oid.from.string("50e99acfb35de75402002023") pipe_1 <- mongo.bson.from.list(list('$match' = list('likes.id' =  oid))) pipe_2 <- mongo.bson.from.json('{"$project" : {"likes" : "$likes.id", "_id" : 0}}') pipe_3 <- mongo.bson.from.json('{"$unwind" : "$likes"}') pipe_4 <- mongo.bson.from.list(list('$match' = list('likes' =  oid))) pipe_5 <- mongo.bson.from.json('{"$group" : {"_id" : "$likes", "count" : {"$sum":1}}}') pipe_6 <- mongo.bson.from.json('{"$sort" : {"count" : 1}}') 

that makes "likes" array of values , not "key/value" pair. don't need "$likes.id" in later stages. reference "$likes".

--

for record, went through sample document collection seem have defined:

{     "_id" : objectid("50e99acfb35de75402002023"),     "likes" : [             {                     "id" : objectid("50e99acfb35de75402002023")             },             {                     "id" : objectid("50e99acfb35de75402002023")             },             {                     "id" : objectid("50e99acfb35de75402002023")             },             {                     "id" : objectid("50e99acfb35de75402002023")             }     ] } 

then defined pipeline in r using bson.from.list` contructors so:

pipeline <- list(     mongo.bson.from.list(list(         '$match' =  list(             'likes.id' = mongo.oid.from.string("50e99acfb35de75402002023")          )     )),     mongo.bson.from.list(list(         '$project' = list(             '_id' = 0,             'likes' = '$likes.id'         )     )),     mongo.bson.from.list(list(         '$unwind' = '$likes'     )),     mongo.bson.from.list(list(         '$match' =  list(             'likes' = mongo.oid.from.string("50e99acfb35de75402002023")          )     )),     mongo.bson.from.list(list(         '$group' = list(             '_id' = '$likes',             'count' = list( '$sum' = 1 )         )     )),     mongo.bson.from.list(list(         '$sort' = list( 'count' = 1 )     )) )  mongo.aggregation(mongo, "test.posts", pipeline) 

and me correctly adds matching entries within array.

also "note" additional match stage here after $unwind. first $match in aggregation matches "document", nothing "filter" array content, items in array still contain things not match "id" value asked for.

so after processing $unwind need "filter" $match again once array has been denormalized. there more efficient ways of doing , documented on site even: retrieve queried element in object array in mongodb collection

but should using bson.from.list , general list() contructors structure rather converting json.