database - MongoDB count occurances of a substring in a collection -

hello i'm mongodb beginner. have database of irc chatlog. document structure simple

{      "_id" : objectid("000"),      "user" : "username",      "message" : "foobar foobar potato idontknow",      "time" : numberlong(1451775601469) } 

i have thousands of these , want count number of occurrences of string "foobar". have googled issue , found aggregations. looks complicated , haven't found issue "simple". i'd glad if pointed me in right direction research , wouldn't mind example command want. thank you.

there no built-in operator solve request.

you can try query, has poor performance:

db.chat.find().foreach(function(doc){     print(doc["user"] + " > " + ((doc["message"].match(/foobar/g) || []).length)) }) 

if change message field array, apply aggregation...

edit:

if add array of splitted words entry, can apply aggregation

sample:

{     "_id" : objectid("569bb7040586bcb40f7d2539"),     "user" : "username",     "fullmessage" : "foobar foobar potato idontknow",     "message" : [          "foobar",          "foobar",          "potato",          "idontknow"     ],     "time" : numberlong(1451775601469) } 

aggregation. create new entry each array element, match given word (foobar, in case) , count matched result.

db.chat.aggregate([     {"$unwind" : "$message"},     {"$match" : {"message" : {"$regex" : "foobar", "$options" : "i"}}},     {"$group" : {_id:{"_id" : "$_id", "user" : "$user", "time" : "$time", "fullmessage" : "$fullmessage"}, "count" : {$sum:1}}},     {"$project" : {_id:"$_id._id", "user" : "$_id.user", "time" : "$_id.time", "fullmessage" : "$_id.fullmessage", "count" : "$count"}} ]) 

result:

[      {         "_id" : objectid("569bb7040586bcb40f7d2539"),         "count" : 2,         "user" : "username",         "time" : numberlong(1451775601469),         "fullmessage" : "foobar foobar potato idontknow"     } ]