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"}
}
}
)
Related
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
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': '$scores.score'
}
}
])
This would output:
{
"_id" : 5,
"name" : "Wilburn Spiess",
"score" : 44.8718633018126
},
{
"_id" : 6,
"name" : "Jenette Flanders",
"score" : 37.322854591661
},
{
"_id" : 7,
"name" : "Salena Olmos",
"score" : 90.3782650915718
}
Considering I have the following documents in a collection (ignoring the _id) :
[
{
"Id": "OP01",
"Sessions": [
{
"Id": "Session01",
"Conversations": [
{
"Id": "Conversation01",
"Messages": [
{
"Id": "Message01",
"Status": "read",
"Direction": "inbound"
},
{
"Id": "Message02",
"Status": "delivered",
"Direction": "internal"
},
{
"Id": "Message03",
"Status": "delivered",
"Direction": "inbound"
},
{
"Id": "Message04",
"Status": "sent",
"Direction": "outbound"
}
]
},
{
"Id": "Conversation02",
"Messages": [
{
"Id": "Message05",
"Status": "sent",
"Direction": "outbound"
}
]
}
]
},
{
"Id": "Session02",
"Conversations": [
{
"Id": "Conversation03",
"Messages": [
{
"Id": "Message06",
"Status": "read",
"Direction": "inbound"
},
{
"Id": "Message07",
"Status": "delivered",
"Direction": "internal"
}
]
},
{
"Id": "Conversation04",
"Messages": []
}
]
}
]
},
{
"Id": "OP02",
"Sessions": [
{
"Id": "Session03",
"Conversations": []
}
]
},
{
"Id": "OP03",
"Sessions": []
}
]
First query — aggregate (+$project)
I want to get the list of Messages grouped by their Conversations where:
Sessions.Id: "Session01"
and
Sessions.Conversations.Messages.Direction $in ["inbound", "outbound"]
and
Sessions.Conversations.Messages.Status $in ["sent", "delivered"]
The expected result is:
[
{
"Id": "Conversation01",
"Messages": [
{
"Id": "Message03",
"Status": "delivered",
"Direction": "inbound"
},
{
"Id": "Message04",
"Status": "sent",
"Direction": "outbound"
}
]
},
{
"Id": "Conversation02",
"Messages": [
{
"Id": "Message05",
"Status": "sent",
"Direction": "outbound"
}
]
}
]
A side note:
If on different documents (or on different Sessions) the Sessions.Id: "Session01" condition is verified ("Session01"is not an unique key), the document's Messages that match the other conditions should also be added.
The result output doesn't mention neither the document or Sessions levels.
Second query — update
I want to update the Sessions.Conversations.Messages.Status of all those messages (same condition as before) to "read".
The collection should have now the following documents:
Please note the changes on:
Sessions.Conversations.Messages.Id = "Message03"
Sessions.Conversations.Messages.Id = "Message04"
Sessions.Conversations.Messages.Id = "Message05"
at Sessions.Id = "Session01"
[
{
"Id": "OP01",
"Sessions": [
{
"Id": "Session01",
"Conversations": [
{
"Id": "Conversation01",
"Messages": [
{
"Id": "Message01",
"Status": "read",
"Direction": "inbound"
},
{
"Id": "Message02",
"Status": "delivered",
"Direction": "internal"
},
{
"Id": "Message03",
"Status": "read",
"Direction": "inbound"
},
{
"Id": "Message04",
"Status": "read",
"Direction": "outbound"
}
]
},
{
"Id": "Conversation02",
"Messages": [
{
"Id": "Message05",
"Status": "read",
"Direction": "outbound"
}
]
}
]
},
{
"Id": "Session02",
"Conversations": [
{
"Id": "Conversation03",
"Messages": [
{
"Id": "Message06",
"Status": "read",
"Direction": "inbound"
},
{
"Id": "Message07",
"Status": "delivered",
"Direction": "internal"
}
]
},
{
"Id": "Conversation04",
"Messages": []
}
]
}
]
},
{
"Id": "OP02",
"Sessions": [
{
"Id": "Session03",
"Conversations": []
}
]
},
{
"Id": "OP03",
"Sessions": []
}
]
How can I accomplish these results with an aggregate and update_one queries?
Here comes a visual explanation of both queries:
I have written the aggregation query
db.session.aggregate([
{
$unwind:"$Sessions"
},
{
$unwind:"$Sessions.Conversations"
},
{
$unwind:"$Sessions.Conversations.Messages"
},
{
$match:{
"Sessions.Id" : "Session01",
"Sessions.Conversations.Messages.Direction":{
$in:[
"inbound", "outbound"
]
},
"Sessions.Conversations.Messages.Status":{
$in:[
"sent", "delivered"
]
}
}
},
{
$group:{
"_id":"$Sessions.Conversations.Id",
"Messages":{
$push:"$Sessions.Conversations.Messages"
}
}
}
]).pretty()
Output
{
"_id" : "Conversation02",
"Messages" : [
{
"Id" : "Message05",
"Status" : "sent",
"Direction" : "outbound"
}
]
}
{
"_id" : "Conversation01",
"Messages" : [
{
"Id" : "Message03",
"Status" : "delivered",
"Direction" : "inbound"
},
{
"Id" : "Message04",
"Status" : "sent",
"Direction" : "outbound"
}
]
}
Now to Update the document:
I have used the positional-filters
db.session.update(
{},
{
$set:{
"Sessions.$[session].Conversations.$[].Messages.$[message].Status":"read"
}
},
{
"arrayFilters": [{"session.Id":"Session01"},{ "message.Id": "Message05" }]
}
)
This will update the status as read for "session.Id":"Session01" and "message.Id": "Message05"
Hope this will help you. :)
UPDATE
db.session.update(
{},
{
$set:{
"Sessions.$[session].Conversations.$[].Messages.$[message].Status":"read"
}
},
{
"arrayFilters": [
{
"session.Id":"Session01"
},
{
"message.Direction": {
$in :[
"inbound",
"outbound"
]
},
"message.Status": {
$in :[
"sent",
"delivered"
]
}
}
]
}
)
How do I get a summary count in Mongo. I have the following record structure and I would like to get a summary by date and status
{
"_id": "1",
"History": [
{
"id": "11",
"message": "",
"status": "send",
"resultCount": 0,
"createdDate": "",
"modifiedDate": ""
},
{
"id": "21",
"message": "",
"status": "skipped",
"resultCount": 0,
"createdDate": "",
"modifiedDate": ""
}
]
}
This is what I would like..
date x
status :
count : nn
This is my Mongo structure
Let's assume you have the following data in 'history' collection:
{
"_id": "1",
"History": [
{
"id": "21",
"message": "",
"status": "send",
"resultCount": 0,
"createdDate": "date1",
"modifiedDate": ""
},
{
"id": "22",
"message": "",
"status": "skipped",
"resultCount": 0,
"createdDate": "date1",
"modifiedDate": ""
},
{
"id": "23",
"message": "",
"status": "skipped",
"resultCount": 0,
"createdDate": "date2",
"modifiedDate": ""
},
{
"id": "24",
"message": "",
"status": "skipped",
"resultCount": 0,
"createdDate": "date2",
"modifiedDate": ""
}
]
}
You can design your query in the following way to get the desired summary.
db.history.aggregate([
{
$unwind:"$History"
},
{
$group:{
"_id":{
"createdDate":"$History.createdDate",
"status":"$History.status"
},
"createdDate":{
$first: "$History.createdDate"
},
"status":{
$first:"$History.status"
},
"count":{
$sum:1
}
}
},
{
$group:{
"_id":"$createdDate",
"createdDate":{
$first:"$createdDate"
},
"info":{
$push:{
"status":"$status",
"count":"$count"
}
}
}
},
{
$project:{
"_id":0
}
}
]).pretty()
It would result in the following:
{
"createdDate" : "date1",
"info" : [
{
"status" : "skipped",
"count" : 1
},
{
"status" : "send",
"count" : 1
}
]
}
{
"createdDate" : "date2",
"info" : [
{
"status" : "skipped",
"count" : 2
}
]
}
Aggregation stages details:
Stage I: The 'History' array is unwinded i.e. the array would be split and each element would create an individual document.
Stage II: The data is grouped on the basis of 'createdDate' and 'status'. In this stage, the count of status is also calculated.
Stage III: The data is further grouped on the basis of 'createdDate'
only
Stage IV: Eliminating non-required fields from the result
I have a mongo DB with several collections that contain JSON document formats shown below:
{
"questions": [
{
"questionEntry": {
"id": 1,
"info": {
"seasonNumber": 1,
"episodeNumber": 1,
"episodeName": "Days Gone Bye"
},
"questionItem": {
"theQuestion": "q1",
"attachedElement": {
"type": 1,
"value": ""
}
},
"options": [
{
"type": 1,
"value": "o1"
},
{
"type": 1,
"value": "o1"
}
],
"answer": {
"questionId": 1,
"answer": 1
},
"metaTags": [
"Season 1",
"Episode 1",
"Rick Grimmes"
]
}
},
{
"questionEntry": {
"id": 1,
"info": {
"seasonNumber": 1,
"episodeNumber": 1,
"episodeName": "Days Gone Bye"
},
"questionItem": {
"theQuestion": "q2",
"attachedElement": {
"type": 1,
"value": ""
}
},
"options": [
{
"type": 1,
"value": "o2"
},
{
"type": 1,
"value": "o2"
}
],
"answer": {
"questionId": 1,
"answer": 1
},
"metaTags": [
"Season 1",
"Episode 1",
"Rick Grimmes",
"Glenn Rhee"
]
}
}
]
}
I'm able to search for questions.questionEntry.questionItem.theQuestion for a matching criteria with:
db.questions.find({"questions.questionEntry.questionItem.theQuestion" : "q1"},{'questions.$':1}).pretty()
This works well for the questions collection but how would I do the same search across multiple collections?
Many thanks
To use the same query across multiple collections you may have to use the JavaScript bracket notation to access the collections in a loop. For example, the following queries the records database for all the collections (using the db.getCollectionNames() command) with the specified query:
use records
var colls = db.getCollectionNames(), // get all the collections in records db
query = {"questions.questionEntry.questionItem.theQuestion" : "q1"},
projection = {"questions.$": 1};
colls.forEach(function (collection){
var docs = db[collection].find(query, projection).toArray(); // use the bracket notation
docs.forEach(function (doc){ printjson(doc); });
})
You will have to do this by yourself. There is no out-of-the-box support.
You can query MongoDB multi-threaded (depending on your programming language) and aggregate the results to a unified result.