I've tried using $in and $elemMatch to query for all objects matching member_id field within an object array, neither are returning data. Example queries:
db.events.find({"source_site":{"event_hosts":{$in:[{"member_id":12300113}]}}})
and
db.events.find({source_site:{event_hosts:{$elemMatch:{member_id:12300113}}}})
Sample data to query in Mongo:
{
"_id" : ObjectId("541890c2660a17aa1f7b7bd4"),
"source_site" : {
"event_hosts" : [
{
"member_id" : 12300113,
"member_name" : "Sal Corthen"
},
{
"member_id" : 139930702,
"member_name" : "Erin Morgen"
}
]
}
}
What am I doing wrong?
If you want to match a member_id directly, you can use:
db.events.find({"source_site.event_hosts.member_id":12300113})
or using $in:
db.events.find({"source_site.event_hosts.member_id":{$in:[12300113]}})
or using $elemMatch:
db.events.find({"source_site.event_hosts":{$elemMatch:{"member_id":12300113}}})
Related
Here is my news document structure
{
"_id" : ObjectId("5bff0903bd9a221229c7c9b2"),
"title" : "Test Page",
"desc" : "efdfr",
"mediaset_list" : [
{
"_id" : ObjectId("5bfeff94bd9a221229c7c9ae"),
"medias" : [
{
"_id" : ObjectId("5bfeff83bd9a221229c7c9ac"),
"file_type" : "png",
"file" : "https://aws.com/gg.jpg",
"file_name" : "edf.jpg"
},
{
"_id" : ObjectId("5bfeff83bd9a221229c7c9ad"),
"file_type" : "mov",
"file" : "https://aws.com/gg.mov",
"file_name" : "abcd.mov"
}
]
}
]}
The queries that i've tried are given below
Approach 1
db.news.find_and_modify({},{'$pull': {"mediaset_list": {"medias": {"$elemMatch" : {"_id": ObjectId('5bfeff83bd9a221229c7c9ac')}} }}})
Approach 2
db.news.update({},{'$pull': {"mediaset_list.$.medias": {"_id": ObjectId('5bfeff83bd9a221229c7c9ac')}} })
Issue we are facing
The above queries are removing entire elements inside 'mediaset_list' . But i only want to remove the element inside 'medias' matching object ID.
Since you have two nested arrays you have to use arrayFilters to indicate which element of outer array should be modified, try:
db.news.update({ _id: ObjectId("5bff0903bd9a221229c7c9b2") },
{ $pull: { "mediaset_list.$[item].medias": { _id: ObjectId("5bfeff83bd9a221229c7c9ad") } } },
{ arrayFilters: [ { "item._id": ObjectId("5bfeff94bd9a221229c7c9ae") } ] })
So item is used here as a placeholder which will be used by MongoDB to determine which element of mediaset_list needs to be modified and the condition for this placeholder is defined inside arrayFilters. Then you can use $pull and specify another condition for inner array to determine which element should be removed.
From #micki's mongo shell query (Answer above) , This is the pymongo syntax which will update all news document with that media id .
db.news.update_many({},
{
"$pull":
{ "mediaset_list.$[item].medias": { "_id": ObjectId("5bfeff83bd9a221229c7c9ad") } } ,
},
array_filters=[{ "item._id": ObjectId("5bfeff94bd9a221229c7c9ae")}],
upsert=True)
FOR getting all documents, what I write instead of XXXX.
I want to get all values without a criterion. I must use aggregate and match function.
payload.sla.customer.externalId variable is string.
db.collection.aggregate ( [
{ "$match" : {
"payload.sla.customer.externalId" : XXXX
}}
])
collection sample example
{
"_id" : ObjectId("5b929a84aff3dc185627add1"),
"payload" : {
"sla" : {
"customer" : {
"externalId" : "140689900",
}
}
}
}
It's one of my data as JSON format:
{
"_id" : ObjectId("5bfdb412a80939b6ed682090"),
"accounts" : [
{
"_id" : ObjectId("5bf106eee639bd0df4bd8e05"),
"accountType" : "DDA",
"productName" : "DDA1"
},
{
"_id" : ObjectId("5bf106eee639bd0df4bd8df8"),
"accountType" : "VSA",
"productName" : "VSA1"
},
{
"_id" : ObjectId("5bf106eee639bd0df4bd8df9"),
"accountType" : "VSA",
"productName" : "VSA2"
}
]
}
I want to make a query to get all productName(no duplicate) of accountType = VSA.
I write a mongo query:
db.Collection.distinct("accounts.productName", {"accounts.accountType": "VSA" })
I expect: ['VSA1', 'VSA2']
I get: ['DDA','VSA1', 'VSA2']
Anybody knows why the query doesn't work in distinct?
Second parameter of distinct method represents:
A query that specifies the documents from which to retrieve the distinct values.
But the thing is that you showed only one document with nested array of elements so whole document will be returned for your condition "accounts.accountType": "VSA".
To fix that you have to use Aggregation Framework and $unwind nested array before you apply the filtering and then you can use $group with $addToSet to get unique values. Try:
db.col.aggregate([
{
$unwind: "$accounts"
},
{
$match: {
"accounts.accountType": "VSA"
}
},
{
$group: {
_id: null,
uniqueProductNames: { $addToSet: "$accounts.productName" }
}
}
])
which prints:
{ "_id" : null, "uniqueProductNames" : [ "VSA2", "VSA1" ] }
I have a collection of persons whose schema looks like the collection of following documents.
Document: {
name:
age:
educations:[{
title:xyz,
passed_year:2005,
univercity:abc},
{
title:asd
passed_year:2007,
univercity:mno
}],
current_city:ghi
}
Now I wanna show all the persons who has not done xyz education from abc university in year 2005.
I think two possible queries for this need but not sure which one to use as both of them are giving me the output
Query 1:
db.persons.find({"education":{$ne:{$elemMatch:{"title":"xyz","passed_year":2005,"univercity":"abc"}}}})
Query 2:
db.persons.find({"education":{$not:{$elemMatch:{"title":"xyz","passed_year":2005,"univercity":"abc"}}}})
I'm quite confused about operator $ne and $not, which one should I use with $elemMatch as both of them are giving me the output.
Given this $elemMatch: {"title":"xyz","passed_year":2005,"univercity":"abc"} I think you want to exclude any documents which contain an sub document in the educations array which contains all of these pairs:
"title" : "xyz"
"passed_year" : 2005
"univercity" : "abc"
This query will achieve that:
db.persons.find({
"educations": {
$not: {
$elemMatch:{"title": "xyz", "passed_year": 2005, "univercity": "abc"}
}
}
})
In your question you wrote:
both of them are giving me the output
I suspect this is because your query is specifying education whereas the correct attribute name is educations. By specifying education you are adding a predicate which cannot be evaluated since it references a non existent document attribute so regardless of whether that predicate uses $ne or $not it will simply not be applied.
In answer to the question of which operator to use: $not or $ne: if you run the above query with .explain(true) you'll notice that the parsed query produced by Mongo is very different for each of these operators.
Using $ne
"parsedQuery" : {
"$not" : {
"educations" : {
"$eq" : {
"$elemMatch" : {
"title" : "xyz",
"passed_year" : 2005,
"univercity" : "abc"
}
}
}
}
}
Using $not:
"parsedQuery" : {
"$not" : {
"educations" : {
"$elemMatch" : {
"$and" : [
{
"passed_year" : {
"$eq" : 2005
}
},
{
"title" : {
"$eq" : "xyz"
}
},
{
"univercity" : {
"$eq" : "abc"
}
}
]
}
}
}
}
So, it looks like use of $ne causes Mongo to do something like this psuedo code ...
not educations equalTo "$elemMatch" : {"title" : "xyz", "passed_year" : 2005, "univercity" : "abc"}
... i.e. it treats the elemMatch clause as if it is the RHS of an equality operation whereas use of $not causes Mongo to actually evaluate the elemMatch clause.
I'm trying to retrieve an object from an array in mongodb. Below is my document:
{
"_id" : ObjectId("53e9b43968425b29ecc87ffd"),
"firstname" : "john",
"lastname" : "smith",
"trips" : [
{
"submitted" : 1407824585356,
"tripCategory" : "staff",
"tripID" : "1"
},
{
"tripID" : "2",
"tripCategory" : "volunteer"
},
{
"tripID" : "3",
"tripCategory" : "individual"
}
]
}
My ultimate goal is to update only when trips.submitted is absent so I thought I could query and determine what the mongo find behavior would look like
if I used the $and query operator. So I try this:
db.users.find({
$and: [
{ "trips.tripID": "1" },
{ "trips": { $elemMatch: { submitted: { $exists: true } } } }
]
},
{ "trips.$" : 1 } //projection limits to the FIRST matching element
)
and I get this back:
{
"_id" : ObjectId("53e9b43968425b29ecc87ffd"),
"trips" : [
{
"submitted" : 1407824585356,
"tripCategory" : "staff",
"tripID" : "1"
}
]
}
Great. This is what I want. However, when I run this query:
db.users.find({
$and: [
{ "trips.tripID": "2" },
{ "trips": { $elemMatch: { submitted: { $exists: true } } } }
]
},
{ "trips.$" : 1 } //projection limits to the FIRST matching element
)
I get the same result as the first! So I know there's something odd about my query that isn't correct. But I dont know what. The only thing I've changed between the queries is "trips.tripID" : "2", which in my head, should have prompted mongo to return no results. What is wrong with my query?
If you know the array is in a specific order you can refer to a specific index in the array like this:-
db.trips.find({"trips.0.submitted" : {$exists:true}})
Or you could simply element match on both values:
db.trips.find({"trips" : {$elemMatch : {"tripID" : "1",
"submitted" : {$exists:true}
}}})
Your query, by contrast, is looking for a document where both are true, not an element within the trips field that holds for both.
The output for your query is correct. Your query asks mongo to return a document which has the given tripId and the field submitted within its trips array. The document you have provided in your question satisfies both conditions for both tripIds. You are getting the first element in the array trips because of your projection.
I have assumed you will be filtering records by the person's name and then retrieving the elements inside trips based on the field-exists criteria. The output you are expecting can be obtained using the following:
db.users.aggregate(
[
{$match:
{
"firstname" : "john",
"lastname" : "smith"
}
},
{$unwind: "$trips"},
{$match:
{
"trips.tripID": "1" ,
"trips.submitted": { $exists: true }
}
}
]
)
The aggregation pipeline works as follows. The first $match operator filters one document (in this case the document for john smith) The $unwind operator in mongodb aggregation unwinds the specified array (trips in this case), in effect denormalizing the sub-records associated with the parent records. The second $match operator filters the denormalized/unwound documents further to obtain the one required as per your query.