Match key name and show document in Mongodb? - mongodb

Question

Json Structure:
"_id" : ObjectId("55d6cb28725f3019a5241781"),
"Number" : {
"value" : "1234567",
},
"DeviceID" : {
"value" : "01",
}
"type" : {
"value" : "ce06"}
Now i want to find only those keys document which start from /dev/.
i tried this script:
var cur = db.LIVEDATA.find({"ProductIMEIno.value":"359983007488004"});
cur.forEach(function(doc){
var keynames = Object.keys(doc);
print('the length is '+keynames.length);
for(var i=0;i<keynames.length;i++){
if(keynames[i].match(/Dev/)){
print("the name is "+keynames); }}} )
but this is not working properly.
Desired Output;
Only this document should show on the basis of key name search.
"DeviceID" : {
"value" : "01",

Answer 1

MongoDB isn't designed to find keys dynamically like this; it's much easier to use it to find values dynamically, so you could restructure your data structure to allow this:
"_id" : ObjectId("55d6cb28725f3019a5241781"),
"data" : [
{
"key" : "Number",
"value" : "1234567",
},
{
"key": "DeviceID",
"value" : "01",
},
{
"key" : "type",
"value" : "ce06"
}
]
Then you will be able to query it like this:
db.LIVEDATA.aggregate([
{$match: {"ProductIMEIno.value":"359983007488004"}},
{$unwind: "$data"},
{$match: {"data.key" : /^dev/i }}
]);
That will return data structured like this:
{
"_id" : ObjectId("55d6cb28725f3019a5241781"),
"data" : {
"key" : "DeviceID",
"value" : "01"
}
}

Answer 2

Suppose you have a data collection like this:
[
{
"Number": {
"value": "1234567"
},
"DeviceID": {
"value": "01"
},
"DeviceID2": {
"value": "01",
"name": "abc123"
},
"type": {
"value": "ce06"
}
},
{
"Number": {
"value": "1234568"
},
"DeviceID": {
"value": "02"
},
"type": {
"value": "ce07"
}
}
]
You can use following aggregation:
db.collection.aggregate([
{
"$match": {}
},
{
"$addFields": {
"root_key_value_list": {
"$objectToArray": "$$ROOT"
}
}
},
{
"$unwind": "$root_key_value_list"
},
{
"$match": {
"root_key_value_list.k": {
"$regex": "^Dev"
}
}
},
{
"$group": {
"_id": "$_id",
"root_key_value_list": {
"$push": "$root_key_value_list"
}
}
},
{
"$project": {
"root": {
"$arrayToObject": "$root_key_value_list"
}
}
},
{
"$replaceRoot": {
"newRoot": "$root"
}
}
])
the result will be:
[
{
"DeviceID": {
"value": "01"
},
"DeviceID2": {
"name": "abc123",
"value": "01"
}
},
{
"DeviceID": {
"value": "02"
}
}
]
playground:
https://mongoplayground.net/p/z5EeHALCqzy