Here is an example of one of my JSON docs:
{
"_id": 1,
"SongId": 1,
"Details": {
"Artist": "Cyndi Lauper",
"Album": "She's So Unusual",
"ReleaseYear": 1983
},
"SongTitle": "Girls Just Want To Have Fun"
}
How would one write a query to move the location of "Artist" and it's value out of the "Details" document, leaving "Album" & "ReleaseYear" still embedded.
In addition to updating the name of a field, the $rename operator can be used to move fields out of (or into) embedded documents.
When working with fields in embedded documents you need to use dot notation to refer to the field name.
Assuming a collection name of discography, you could move your Details.Artist field using:
db.discography.update(
{_id: 1},
{$rename: { "Details.Artist": "Artist"}}
)
Example result:
> db.discography.findOne({_id: 1})
{
"_id" : 1,
"SongId" : 1,
"Details" : {
"Album" : "She's So Unusual",
"ReleaseYear" : 1983
},
"SongTitle" : "Girls Just Want To Have Fun",
"Artist" : "Cyndi Lauper"
}
Related
In my database.collection i.e. db.blog.posts I am trying to add a key and value that itself has multiple keys and values.
Current collection:
db.blog.posts.findOne()
"title":"blog posts"
I tried using $set, $push but nothing seems to work.
This also didn't work when I tried adding single collection:
db.blog.posts.updateOne({"title":"blog posts"}, {"$set":{"comments":[{"comment":"good post", "author":"john","votes":0}]}})
Nor insertOne instead of updateOne and I even tried with:
var myEmployee=[
{"comment":"good post", "author":"john", "votes":0},
{"comment":"i thought it was too short", "author":"claire","votes":3},
{"comment":"free watches", "author":"claire","votes":-1},
];
db.blog.posts.insert(myEmployee)
This is what I want:
"title" : "A blog post",
"comments" : [
{
"name" : "joe",
"email" : "joe#example.com",
"content" : "nice post."
},
{
"name" : "bob",
"email" : "bob#example.com",
"content" : "good post."
}
]
The updateOne command you have should have created an array for comments with a single entry. If you wanted multiple entries, you can just add multiple objects to the array in the update. The $set operator will change the value of the key to what you set as the second parameter.
db['blog.posts'].updateOne({"title":"blog posts"}, {
"$set": {
"comments":[
{
"name" : "joe",
"email" : "joe#example.com",
"content" : "nice post."
},
{
"name" : "bob",
"email" : "bob#example.com",
"content" : "good post."
}
]
}
})
If you want to add additional items to the comments, this can be done with $push. The $push operator adds to the array.
db['blog.posts'].updateOne({"title":"blog posts"}, {
"$push": {
"comments": {
"comment": "good post",
"author": "john",
"votes": 0
}
}
})
Docs for $set
Docs for $push
NB the examples above are for a collection named 'blog.posts' rather than a database named 'blog' and a collection names 'posts'. Ideally, brackets should be used for the property accessor where the collection name is not a valid JavaScript identifier although the dot notation in the question still works.
I am trying to add versioning levels in a document as well as its subdocuments. Heres a schema example
{
"_id" : ObjectId("59d1312a8ee6de1858933950"),
"synonyms" : [
{
"_id" : ObjectId("59d1312a8ee6de1858933954"),
"text" : [
1.0,
2.0,
3.0
],
"__v" : 1.0
},
{
"_id" : ObjectId("59d1312a8ee6de1858933953"),
"text" : [
"Foo ",
"bar ",
"Baz"
],
"__v" : 0
},
{
"_id" : ObjectId("59d1312a8ee6de1858933951"),
"text" : [
"fizz",
"bazz",
"bizz"
],
"__v" : 0
}
],
"__v" : 3.0
}
As you can see , the parent document has its own __v while each subdocument (part of the synonyms array) also has its __v . What i'm trying to accomplish is this
When updating a subdocument array - increment the version of the subdocument as well as its parent version
to that effect , i've tried the below code
db.collection.update({
'_id': ObjectId("59d1312a8ee6de1858933950"),
"synonyms._id": ObjectId("59d1312a8ee6de1858933954")
},
{$set: {'synonyms.$.text': [1,2,3]}, $inc: {'synonyms.$.__v': 1}, $inc: {"__v": 1}}
)
My parent __v is getting increment on every update but the subdocument seems to be stuck at 1.0 no matter how many updates i go through. Is there a better way?
If you think about the parameters that you pass to a MongoDB command as a JSON document rather than a string this makes perfect sense: Passing in the same operator twice (as in $inc at the start and later another $inc again in your example) will create a JSON document that only contains the last parameter. This would be different if you were using a string here which would actually represent a JSON document with two $inc fields.
So here's how to get it right (basically by $incing two fields as part of a single operation):
db.collection.update({
'_id': ObjectId("59d1312a8ee6de1858933950"),
"synonyms._id": ObjectId("59d1312a8ee6de1858933954")
},
{$set: {'synonyms.$.text': [1,2,3]}, $inc: {'synonyms.$.__v': 1, "__v": 1}}
)
This question already has answers here:
Retrieve only the queried element in an object array in MongoDB collection
(18 answers)
Closed 8 years ago.
If I have the following document
{
"_id" : ObjectId("54986d5531a011bb5fb8e0ee"),
"owner" : "54948a5d85f7a9527a002917",
"type" : "group",
"deleted" : false,
"participants" : [
{ "_id": "54948a5d85f7a9527a002917", "name": "user1" },
{ "_id": "5491234568f7a9527a002918", "name": "user2" },
{ "_id": "5491234568f7a9527a002918", "name": "user3" },
{ "_id": "1234567aaaa7a9527a002917", "name": "user2" }
]
}
How would I get all records where name = 'user2'?
I'm trying the followoing:
db.users.find({ _id: ObjectId('54a7103b1a57eee00bc0a9e4') },
{ 'participants.$.name': 'user2') }).pretty()
...and I get the following:
error: {
"$err" : "Can't canonicalize query: BadValue Positional projection 'participants.$.name' does not match the query document.",
"code" : 17287
}
Though the positional operator($) would give you the first matching element from the participant array. If you need all the participants in with the name user2, you need to aggregate the results.
Match the document with the required _id.
Use the redact operator to only keep all the sub documents that have
participants, who have their name as user2.
Code:
var search = "user2";
db.users.aggregate([
{$match:{"_id":ObjectId("54986d5531a011bb5fb8e0ee")}},
{$redact:{$cond:[{$eq:[{$ifNull:["$name",search]},search]},
"$$DESCEND",
"$$PRUNE"]}},
{$project:{"participants":1,"_id":0}} // set _id:1, if you need the _id.
])
o/p:
{
"participants" : [
{
"_id" : "5491234568f7a9527a002918",
"name" : "user2"
},
{
"_id" : "1234567aaaa7a9527a002917",
"name" : "user2"
}
]
}
Coming to your query,
db.users.find({ _id: ObjectId('54a7103b1a57eee00bc0a9e4') },
{ 'participants.$.name': 'user2'}).pretty()
The positional operator can be applied only on the array, that is referred in the query document of the find function. The above query document doesn't have a reference to the array named participants and only refers to the _id field to match a document. Hence you get the error.
From the docs,
The field being limited must appear in the query document
So, changing the query to include the participants array in the query document would fix the error.
db.users.find({ "_id":ObjectId('54a7103b1a57eee00bc0a9e4'),
"participants.name": "user2"
},
{"participants.$.name":"user2"}).pretty()
But it would return you only the first participant that has matched the criteria in the query document.
From the docs,
Use $ in the projection document of the find() method or the findOne()
method when you only need one particular array element in selected
documents.
o/p:
{
"_id" : ObjectId("54986d5531a011bb5fb8e0ee"),
"participants" : [
{
"_id" : "5491234568f7a9527a002918",
"name" : "user2"
}
]
}
I have a collection :
gStats : {
"_id" : "id1",
"criteria" : ["key1":"value1", "key2":"value2"],
"groups" : [
{"id":"XXXX", "visited":100, "liked":200},
{"id":"YYYY", "visited":30, "liked":400}
]
}
I want to be able to update a document of the stats Array of a given array of criteria (exact match).
I try to do this on 2 steps :
Pull the stat document from the array of a given "id" :
db.gStats.update({
"criteria" : {$size : 2},
"criteria" : {$all : [{"key1" : "2096955"},{"value1" : "2015610"}]}
},
{
$pull : {groups : {"id" : "XXXX"}}
}
)
Push the new document
db.gStats.findAndModify({
query : {
"criteria" : {$size : 2},
"criteria" : {$all : [{"key1" : "2015610"}, {"key2" : "2096955"}]}
},
update : {
$push : {groups : {"id" : "XXXX", "visited" : 29, "liked" : 144}}
},
upsert : true
})
The Pull query works perfect.
The Push query gives an error :
2014-12-13T15:12:58.571+0100 findAndModifyFailed failed: {
"value" : null,
"errmsg" : "exception: Cannot create base during insert of update. Cause
d by :ConflictingUpdateOperators Cannot update 'criteria' and 'criteria' at the
same time",
"code" : 12,
"ok" : 0
} at src/mongo/shell/collection.js:614
Neither query is working in reality. You cannot use a key name like "criteria" more than once unless under an operator such and $and. You are also specifying different fields (i.e groups) and querying elements that do not exist in your sample document.
So hard to tell what you really want to do here. But the error is essentially caused by the first issue I mentioned, with a little something extra. So really your { "$size": 2 } condition is being ignored and only the second condition is applied.
A valid query form should look like this:
query: {
"$and": [
{ "criteria" : { "$size" : 2 } },
{ "criteria" : { "$all": [{ "key1": "2015610" }, { "key2": "2096955" }] } }
]
}
As each set of conditions is specified within the array provided by $and the document structure of the query is valid and does not have a hash-key name overwriting the other. That's the proper way to write your two conditions, but there is a trick to making this work where the "upsert" is failing due to those conditions not matching a document. We need to overwrite what is happening when it tries to apply the $all arguments on creation:
update: {
"$setOnInsert": {
"criteria" : [{ "key1": "2015610" }, { "key2": "2096955" }]
},
"$push": { "stats": { "id": "XXXX", "visited": 29, "liked": 144 } }
}
That uses $setOnInsert so that when the "upsert" is applied and a new document created the conditions specified here rather than using the field values set in the query portion of the statement are used instead.
Of course, if what you are really looking for is truly an exact match of the content in the array, then just use that for the query instead:
query: {
"criteria" : [{ "key1": "2015610" }, { "key2": "2096955" }]
}
Then MongoDB will be happy to apply those values when a new document is created and does not get confused on how to interpret the $all expression.
I have a document structure like follows:
{
"_id": ...,
"name": "Document name",
"properties": {
"prop1": "something",
"2ndprop": "other_prop",
"other3": ["tag1", "tag2"],
}
}
I can't know the actual field names in properties subdocument (they are given by the application user), so I can't create indexes like properties.prop1. Neither can I know the structure of the field values, they can be single value, embedded document or array.
Is there any practical way to do performant queries to the collection with this kind of schema design?
One option that came to my mind is to add a new field to the document, index it and set used field names per document into this field.
{
"_id": ...,
"name": "Document name",
"properties": {
"prop1": "something",
"2ndprop": "other_prop",
"other3": ["tag1", "tag2"],
},
"property_fields": ["prop1", "2ndprop", "other3"]
}
Now I could first run query against property_fields field and after that let MongoDB scan through the found documents to see whether properties.prop1 contains the required value. This is definitely slower, but could be viable.
One way of dealing with this is to use schema like below.
{
"name" : "Document name",
"properties" : [
{
"k" : "prop1",
"v" : "something"
},
{
"k" : "2ndprop",
"v" : "other_prop"
},
{
"k" : "other3",
"v" : "tag1"
},
{
"k" : "other3",
"v" : "tag2"
}
]
}
Then you can index "properties.k" and "properties.v" for example like this:
db.foo.ensureIndex({"properties.k": 1, "properties.v": 1})