Trying to update the nested object for the document in MongoDB.
{
"items" : [
{
"id": 1,
"name": "a",
"child": [
{ "id": 11, "name": "aa" },
{ "id": 12, "name": "bb" },
]
},
]
}
Need to update the child id to 13 whose name is "aa".
O/P, which I am trying to get
{
"items" : [
{
"id": 1,
"name": "a",
"child": [
{ "id": 13, "name": "aa" },
{ "id": 12, "name": "bb" },
]
},
]
}
Work with $[<identifier>] filtered positional operator and arrayFilters.
db.collection.update({
"items.child.name": "aa"
},
{
$set: {
"items.$[].child.$[c].id": 13
}
},
{
arrayFilters: [
{
"c.name": "aa"
}
]
})
Sample Mongo Playground
Related
// orders collection
[
{
"id": 1,
"orderName": "a",
"seqId": 100,
"etc": [],
"desc": [],
},
{
"id": 2,
"orderName": "b",
"seqId": 200,
"etc": [],
"desc": []
},
{
"id": 3,
"orderName": "c",
"seqId": 100,
"etc": [],
"desc": [],
},
]
// goods collection
[
{
"id": 1,
"title": "example1",
"items": [
{
"id": 10,
"details": [
{
"id": 100
},
{
"id": 101,
}
]
},
{
"id": 20,
"details": [
{
"id": 102,
},
{
"id": 103,
}
]
},
]
},
[
{
"id": 2,
"title": "example2",
"items": [
{
"id": 30,
"details": [
{
"id": 200
},
{
"id": 201
}
]
},
{
"id": 40,
"details": [
{
"id": 202
},
{
"id": 203
}
]
},
]
},
]
When the value of the seqId field of the document whose etc field and desc field arrays of the orders collection are empty and the value of the "goods.details.id field of the goods collection are the same, I want to get the following output. How can I do that?
[
{orderName: "a", title: "example1"},
{orderName: "b", title: "example2"},
{orderName: "c", title: "example1"},
]
Additionally, I would like to perform a sum operation based on the title of the goods
collection.
[
{"example1": 2},
{"example2": 1}
]
Simply perform a $lookup between orders.seqId and goods.items.details.id. Use $unwind to eliminate empty lookups(i.e. inner join behaviour). Finally, do a $group with $sum to get the count.
db.orders.aggregate([
{
"$match": {
"etc": [],
"desc": []
}
},
{
"$lookup": {
"from": "goods",
"localField": "seqId",
"foreignField": "items.details.id",
"pipeline": [
{
$project: {
_id: 0,
title: 1
}
}
],
"as": "goodsLookup"
}
},
{
"$unwind": "$goodsLookup"
},
{
$group: {
_id: "$goodsLookup.title",
cnt: {
$sum: 1
}
}
}
])
Mongo Playground
If these are the following nested documents
[
{
"_id": 5,
"name": "Wilburn Spiess",
"scores": [
{
"score": 44.87186330181261,
"type": "exam"
},
{
"score": 25.72395114668016,
"type": "quiz"
},
{
"score": 63.42288310628662,
"type": "homework"
}
]
},
{
"_id": 6,
"name": "Jenette Flanders",
"scores": [
{
"score": 37.32285459166097,
"type": "exam"
},
{
"score": 28.32634976913737,
"type": "quiz"
},
{
"score": 81.57115318686338,
"type": "homework"
}
]
},
{
"_id": 7,
"name": "Salena Olmos",
"scores": [
{
"score": 90.37826509157176,
"type": "exam"
},
{
"score": 42.48780666956811,
"type": "quiz"
},
{
"score": 96.52986171633331,
"type": "homework"
}
]
}
]
I need to access the score part 'type' = exam.
Can somebody help me with this?
If you're asking for a python program to access the score, you can print them out like:
collection = mongo_connection['db']['collection']
documents = collection.find({})
for doc in documents:
for score in doc['scores']:
if score['type'] == 'exam':
print(f'Score: {score["score"]}')
If you are trying to retrieve only the scores and ignore the rest, I'd do an $unwind on the scores, $match on the type, and then project the fields you want (or not).
db.test.aggregate([
{
$unwind: '$scores'
},
{
$match: {
'scores.type': 'exam'
}
},
{
$project: {
'name': '$name',
'score': '$scores.score'
}
}
])
This would output:
{
"_id" : 5,
"name" : "Wilburn Spiess",
"score" : 44.8718633018126
},
{
"_id" : 6,
"name" : "Jenette Flanders",
"score" : 37.322854591661
},
{
"_id" : 7,
"name" : "Salena Olmos",
"score" : 90.3782650915718
}
I want to aggregate data for the following sample array.
[
{
"_id": "5b7c0540342100091a375793",
"pages": [
{
"name": "ABCD",
"sections": [
{
"name": "sectionThird",
"id": 2,
"value": [
10,
50,
20
]
}
]
}
]
},
{
"_id": "5b3cd546342100514b4683a2",
"pages": [
{
"name": "ABCD",
"sections": [
{
"name": "sectionFourth",
"id": 2,
"value": [
19,
5,
8
]
},
{
"name": "sectionThird",
"id": 2,
"value": [
60
]
}
]
},
{
"name": "EFGH",
"sections": [
{
"name": "sectionFourth",
"id": 2,
"value": [
5
]
},
{
"name": "sectionThsads",
"id": 2,
"value": [
8
]
}
]
}
]
}
]
I want the following output:
[
{
"page": "ABCD",
"sections": [
{
"name": "sectionThird",
"totalValue": 140
},
{
"name": "sectionFourth",
"totalValue": 32
}
]
},
{
"page": "EFGH",
"sections": [
{
"name": "sectionFourth",
"totalValue": 5
},
{
"name": "sectionThsads",
"totalValue": 8
}
]
}
]
In the above sample array, you can see there are multiple documents with "page" as one of the keys which are also an array of objects. Each page object has a key "name" which is going to be unique for each object in "page" array. The "page" object has "sections" key and they also have "name" key in them which is going to be unique for each object.
So the output array is grouped by page.name then in that its grouped by sections.name from all the page objects with the sum of all the value array throughout sections inside a page object with the same section name.
You can use below aggregation.
$unwind each page and section followed by $group with $sum to sum the values for each section and $push to push the sections values back into page array.
db.col.aggregate([
{"$unwind":"$pages"},
{"$unwind":"$pages.sections"},
{"$group":{
"_id":{"pagename":"$pages.name","sectionname":"$pages.sections.name"},
"totalTime":{"$sum":{"$sum":"$pages.sections.value"}}
}},
{"$group":{
"_id":"$_id.pagename",
"sections":{"$push":{"name":"$_id.sectionname","totalTime":"$totalTime"}}
}}])
I have a collection with this structure:
{
"name": "1",
"array1": [
{
"arrayname1A" : "A",
"array2": [
{ "value": "1" },
{ "value": "3" }
]
},
{
"arrayname1B": "B",
"array2": [
{ "value": "5" },
]
}
]
},
{
"name": "2",
"array1": [
{
"arrayname1A": "A",
"array2": [
{ "value": "1" },
{ "value": "7" }
]
}
]
}
How can I extract the unique "value" from every different array2? The end result I am looking for would be something like "1","3","5","7" with no repeated values.
Simply use the distinct() method and the dot notation to access the "value" field.
db.collection.distinct('array1.array2.value')
which yields:
[ "1", "3", "5", "7" ]
I have the following JSON document in my mongoDB which I added with mingoimport.
I am trying to return a single element from the questions array where theQuestion equals "q1".
{
"questions": [
{
"questionEntry": {
"id": 1,
"info": {
"seasonNumber": 1,
"episodeNumber": 1,
"episodeName": "Days Gone Bye"
},
"questionItem": {
"theQuestion": "q1",
"attachedElement": {
"type": 1,
"value": ""
}
},
"options": [
{
"type": 1,
"value": "o1"
},
{
"type": 1,
"value": "o1"
}
],
"answer": {
"questionId": 1,
"answer": 1
},
"metaTags": [
"Season 1",
"Episode 1",
"Rick Grimmes"
]
}
},
{
"questionEntry": {
"id": 1,
"info": {
"seasonNumber": 1,
"episodeNumber": 1,
"episodeName": "Days Gone Bye"
},
"questionItem": {
"theQuestion": "q2",
"attachedElement": {
"type": 1,
"value": ""
}
},
"options": [
{
"type": 1,
"value": "o2"
},
{
"type": 1,
"value": "o2"
}
],
"answer": {
"questionId": 1,
"answer": 1
},
"metaTags": [
"Season 1",
"Episode 1",
"Rick Grimmes",
"Glenn Rhee"
]
}
}
]
}
I ran the query db.questions.find({"questions.questionEntry.questionItem.theQuestion" : "q1"}) but this retruned the whole document (both questionEntry's in question array!
I have tried db.questions.find({"questions.questionEntry.questionItem.theQuestion" : "q1"}, _id:0," questions.questionItem": {$elemMatch : {theQuestion: "q1"}}})
But get the following error:
Error: error: {
"$err" : "Can't canonicalize query: BadValue Cannot use $elemMatch projection on a nested field.", "code" : 17287
Is there a way I could limit the result to just the array element which contains it?
Thanks
db.questions.find({},{"questions.questionEntry.questionItem.theQuestion" : "q1"});
or
db.questions.find({"questions.questionEntry.questionItem.theQuestion" : "q1"},{'questions.$':1});
please try these.
If you want to use $elemMatch the query should be:
db.questions.find(
{"questions.questionEntry.questionItem.theQuestion" : "q1"},
{
'_id':0,
"questions": {
$elemMatch : {"questionEntry.questionItem.theQuestion": "q1"}
}
}
)