Is there a way to query for dict of arrays of array in MongoDB - mongodb

Question

My mongo db collection contains the structure as :
{
"_id" : ObjectId("5889ce0d2e9bfa938c49208d"),
"filewise_word_freq" : {
"33236365" : [
[
"cluster",
4
],
[
"question",
2
],
[
"differ",
2
],[
"come",
1
]
],
"33204685" : [
[
"node",
6
],
[
"space",
4
],
[
"would",
3
],[
"templat",
1
]
]
},
"file_root" : "socialcast",
"main_cluster_name" : "node",
"most_common_words" : [
[
"node",
16
],
[
"cluster",
7
],
[
"n't",
3
]
]
}
I want to search for a value "node" inside the arrays of arrays of the filename (in my case its "33236365","33204685" and so on...) of the dict filewise_word_freq.
And if the value("node") is present inside any one of the array of arrays of the filename(33204685), then should return the filename(33204685).
I tried from this link of stackoverflow :
enter link description here
I tried to execute for my use case it didn't work. And above all this I didn't no how to return only the filename rather the entire object or document.
db.frequencydist.find({"file_root":'socialcast',"main_cluster_name":"node","filewise_word_freq":{$elemMatch:{$elemMatch:{$elemMatch:{$in:["node"]}}}}}).pretty().
It returned nothing.
Kindly help me.

Answer 1

the data model you have chosen has made it extremely difficult to either query or even for aggregation. I would suggest to revise your document model. However I think you can use $where
db.collection.find({"file_root": 'socialcast',
"main_cluster_name": "node", $where : "for(var i in this.filewise_word_freq){for(var j in this.filewise_word_freq[i]){if(this.filewise_word_freq[i][j].indexOf("node")>=0){return true}}}"})
yes, this will return you the whole document and from your application you might need to filter the files name out.
you might also want to see map-reduce functionality, though that's not recommended.
One other way is to do it through functions, functions runs on mongo server and are saved in a special collection.
Still going back to the db model, do revise it if that's a possibility. maybe something like
{
"_id" : ObjectId("5889ce0d2e9bfa938c49208d"),
"filewise_word_freq" : [
{
"fileName":"33236365",
"word_counts" : {
"cluster":4,
"question":2,
"differ":2,
"come":1
}
},
{
"fileName":"33204685",
"word_counts" : {
"node":6,
"space":4,
"would":3,
"template":1
}
}
]
"file_root" : "socialcast",
"main_cluster_name" : "node",
"most_common_words" : [
{
"node":16
},
{
"cluster":7
},
{
"n't":3
}
]
}
It would be a lot easier to run aggregation on these.
For this model, the aggregation would be something like
db.collection.aggregate([
{$unwind : "$filewise_word_freq"},
{$match : {'filewise_word_freq.word_counts.node' : {$gte : 0}}},
{$group :{_id: 1, fileNames : {$addToSet : "$filewise_word_freq.fileName"}}},
{$project :{ _id:0}}
])
this will provide you a single document with a single field fileNames with list of all the filename
{
fileNames : ["33204685"]
}

Answer 2

You can try something like this. This will match the node as part of the query and returns filewise_word_freq.33204685 as part of the projection.
db.collection.find({
"file_root": 'socialcast',
"main_cluster_name": "node",
"filewise_word_freq.33204685": {
$elemMatch: {
$elemMatch: {
$in: ["node"]
}
}
}
}, {
"filewise_word_freq.33204685": 1
}).pretty();