Can some please clarify if the following terms are as I understand them:
Mongo: embedded -> Mongoose: Sub Document
Mongo: referenced documents -> Mongoose: Population
Thank you for the help.
Embedded documents and subdocuments are the same thing:
{
"embeddedDoc" : { "a" : 1, "b" : 2 },
"embeddedDocs" : [
{ "c" : 2, "d" : "cookie" },
{ "s" : 99, "h" : "pie" },
]
}
Both terms are used when talking about MongoDB and Mongoose. I wouldn't say one is a "MongoDB term" and the other is a "Mongoose term".
A referenced document is a document for which some identifier (usually the _id) is stored in another document.
{
"referencedDoc" : "3F6A99E",
"referencedDocs" : [
"22AE5",
"95A11B"
]
}
In some other collection, or even the same collection, there'd be documents with _ids "3F6A99E", "22AE5", and "95A11B". Population is a Mongoose-specific concept. It's the process by which the references are resolved and replaced by the referenced documents, simulating a simple join. For example, after calling .populate() with for the field paths referencedDocs, you might end up with something like
{
"referencedDoc" : "3F6A99E",
"referencedDocs" : [
{ "_id" : "22AE5", "food" : "pickles" },
{ "_id" : "95A11B", "food" : "tuna" }
]
}
Related
I have a collection with the documents like this with 25 documents
{
"_id" : ObjectId("<some id>"),
"code" : "1111",
"myArray" : ["Choocolate"]
},
{
"_id" : ObjectId("<some id>"),
"code" : "2222"
"myArray" : ["Choocolate"]
},
{
"_id" : ObjectId("<some id>"),
"code" : "3333",
"myArray" : ["Choocolate"]
},
{
"_id" : ObjectId("<some id>"),
"code" : "4444",
"myArray" : ["Choocolate"]
}
and so on
I want to add an item to an myArray only fore certain documents based on a condition. so I tried this
db.mycollection.update
({ "code":
{
"$nin": ["1111","2222"]
},
{
$push: { "myArray": "Coffee" }
}
)
I expect 'Coffee' to be added to myArray in all documents except the ones with code 1111 or 2222. But only it is added to an array only in one document.
How to I add an item to anArray in multiple documents based on a condition against a field in a document?
Based on the documentation update updates only a single element:
By default, the db.collection.update() method updates a single document. Include the option multi: true to update all documents that match the query criteria.
https://docs.mongodb.com/manual/reference/method/db.collection.update/
To update more use updateMany:
https://docs.mongodb.com/manual/reference/method/db.collection.updateMany/
I did this in my mongodb:
db.teams.insert({name:"Alpha team",employees:[{name:"john"},{name:"david"}]});
db.teams.insert({name:"True team",employees:[{name:"oliver"},{name:"sam"}]});
db.teams.insert({name:"Blue team",employees:[{name:"jane"},{name:"raji"}]});
db.teams.find({"employees.name":/.*o.*/});
But what I got was:
{ "_id" : ObjectId("5ddf3ca83c182cc5354a15dd"), "name" : "Alpha team", "employees" : [ { "name" : "john" }, { "name" : "david" } ] }
{ "_id" : ObjectId("5ddf3ca93c182cc5354a15de"), "name" : "True team", "employees" : [ { "name" : "oliver" }, { "name" : "sam" } ] }
But what I really want is
[{"name":"john"},{"name":"oliver"}]
I'm having a hard time finding examples of this without using some kind of programmatic iterator/loop. Or examples I find return the parent document, which means I'd have to parse out the embedded array employees and do some kind of UNION statement?
Eg.
How to get embedded document in mongodb?
Retrieve only the queried element in an object array in MongoDB collection
Can someone point me in the right direction?
Please add projections to filter out the fields you don't need. Please refer the project link mongodb projections
Your find query should be constructed with the projection parameters like below:
db.teams.find({"employees.name":/.*o.*/}, {_id:0, "employees.name": 1});
This will return you:
[{"name":"john"},{"name":"oliver"}]
Can be solved with a simple aggregation pipeline.
db.teams.aggregate([
{$unwind : "$employees"},
{$match : {"employees.name":/.*o.*/}},
])
EDIT:
OP Wants to skip the parent fields. Modified query:
db.teams.aggregate([
{$unwind : "$employees"},
{$match : {"employees.name":/.*o.*/}},
{$project : {"name":"$employees.name",_id:0}}
])
Output:
{ "name" : "john" }
{ "name" : "oliver" }
I'm quite new to mongodb and there is one thing I can't solve right now:
Let's pretend, you have the following document structure:
{
"_id": ObjectId("some object id"),
name: "valueName",
options: [
{idOption: "optionId", name: "optionName"},
{idOption: "optionId", name: "optionName"}
]
}
And each document can have multiples options that are already classified.
I'm trying to get all the documents in the collection that have, at least one, of the multiples options that I pass for the query.
I was trying with the operator $elemMatch something like this:
db.collectioName.find({"options.name": { $elemMatch: {"optName1","optName2"}}})
but it never show me the matches documents.
Can someone help and show me, what I'm doing wrong?
Thanks!
Given a collection which contains the following documents:
{
"_id" : ObjectId("5a023b8d027b5bd06add627a"),
"name" : "valueName",
"options" : [
{
"idOption" : "optionId",
"name" : "optName1"
},
{
"idOption" : "optionId",
"name" : "optName2"
}
]
}
{
"_id" : ObjectId("5a023b9e027b5bd06add627d"),
"name" : "valueName",
"options" : [
{
"idOption" : "optionId",
"name" : "optName3"
},
{
"idOption" : "optionId",
"name" : "optName4"
}
]
}
This query ...
db.collection.find({"options": { $elemMatch: {"name": {"$in": ["optName1"]}}}})
.. will return the first document only.
While, this query ...
db.collection.find({"options": { $elemMatch: {"name": {"$in": ["optName1", "optName3"]}}}})
...will return both documents.
The second example (I think) meeets this requirement:
I'm trying to get all the documents in the collection that have, at least one, of the multiples options that I pass for the query.
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 $all expression.
I have a collection that stored information about devices like the following:
/* 1 */
{
"_id" : {
"startDate" : "2012-12-20",
"endDate" : "2012-12-30",
"dimensions" : ["manufacturer", "model"],
"metrics" : ["deviceCount"]
},
"data" : {
"results" : "1"
}
}
/* 2 */
{
"_id" : {
"startDate" : "2012-12-20",
"endDate" : "2012-12-30",
"dimensions" : ["manufacturer", "model"],
"metrics" : ["deviceCount", "noOfUsers"]
},
"data" : {
"results" : "2"
}
}
/* 3 */
{
"_id" : {
"dimensions" : ["manufacturer", "model"],
"metrics" : ["deviceCount", "noOfUsers"]
},
"data" : {
"results" : "3"
}
}
And I am trying to query the documents using the _id field which will be unique. The problem I am having is that when I query for all the different attributes as in:
db.collection.find({$and: [{"_id.dimensions":{ $all: ["manufacturer","model"], $size: 2}}, {"_id.metrics": { $all:["noOfUsers","deviceCount"], $size: 2}}]});
This matches 2 and 3 documents (I don't care about the order of the attributes values), but I would like to only get 3 back. How can I say that there should not be any other attributes to _id than those that I specify in the search query?
Please advise. Thanks.
Unfortunately, I think the closest you can get to narrowing your query results to just unordered _id.dimensions and unordered _id.metrics requires you to know the other possible fields in the _id subdocument field, eg. startDate and endDate.
db.collection.find({$and: [
{"_id.dimensions":{ $all: ["manufacturer","model"], $size: 2}},
{"_id.metrics": { $all:["noOfUsers","deviceCount"], $size: 2}},
{"_id.startDate":{$exists:false}},
{"_id.endDate":{$exists:false}}
]});
If you don't know the set of possible fields in _id, then the other possible solution would be to specify the exact _id that you want, eg.
db.collection.find({"_id" : {
"dimensions" : ["manufacturer", "model"],
"metrics" : ["deviceCount", "noOfUsers"]
}})
but this means that the order of _id.dimensions and _id.metrics is significant. This last query does a document match on exact BSON representation of _id.