Suppose I have the following schema:
{
userId: docId,
skills: [
{
_id: SkillId,
endorsers: [
{
userId: idOfUser
}
]
}
]
}
What I want is a user should not be able to endorse a specific skill in a document more than once. First should find a specific document using its docId, and inside that, a specific skill using skillId, and then check if its endorsers array is empty or a specific user not endorsed yet, then push.
What I tried so far:
{
"userId": req.params.userId,
"skills": {
"$elemMatch": {
"skillId": ObjectId(req.params.skillId),
"$or": [
{"endorsers": []},
{"endorsers.userId":{$ne: endorser._id}}
]
}
}
},
{
"$push": { "skills.$[outer].endorsers": endorserData }
},
{
"arrayFilters": [
{ "outer.skillId": ObjectId(req.params.skillId) }
]
}
But this is not working, and along update, I need the updated result.
You can use addToSet function of mongoose arrays to keep their elements unique. https://mongoosejs.com/docs/api.html#mongoosearray_MongooseArray-addToSet
Related
I have collection MyCollection which basically consists of its _id and a string called comment.
This collection should be bulk-updatable.
That's done like this:
for (const obj of inputObjects) {
bulkObjectsToWrite.push({
updateOne: {
filter: { _id: obj._id },
update: {
$set: {
comment: obj.comment
}
}
}
})
}
await MyCollection.bulkWrite(bulkObjectsToWrite)
So far so good.
However, now the requirement is, that a commentHistory should be added which should look like [{"oldValue": "oldValueOfComment", "newValue": "newValueOfComment"}, ...]
I know I need to use $push for adding a new object to the commentHistory array. But how do I access the comment of the document updated right now, i.e. its current value?
I've tried
$push: {
commentHistory: {
newValue: obj.comment,
oldValue: '$comment',
},
},
but to no avail. The string $comment is added hard-coded, instead of the field being accessed.
(Using Mongoose 5.12.10 and Mongo 4.4.18)
You need to use update with aggregate pipeline.
db.collection.update({
"key": 1
},
[
{
$set: {
"comment": "New",
"commentHistory": {
"$concatArrays": [ //concatenate existing history array with new array entry
"$commentHistory",
[
{
"newValue": "New",
"oldValue": "$comment" //referencing the existing value
}
]
]
}
}
}
])
Demo
I need to find and update documents with category that corresponding to the query. Array could contain mo than one corresponding id.
Query:
{
"ids": ["61f1cda47018c60012b3dd01", "61f1cdb87018c60012b3dd07"],
"userId": "61eab3e57018c60012b3db3f"
}
I got collection with documents like:
`{
"_id":{"$oid":"61f1cdd07018c60012b3dd09"},
"expenses":[
{"category":"61eafc104b88e154caa58616","price":"1111.00"},
{"category":"61f1cdb87018c60012b3dd07","price":"2222.00"},
{"category":"61f1cda47018c60012b3dd01","price":"1241.00"},
{"category":"61f1cdb87018c60012b3dd07","price":"111.00"}
],
"userId":"61eab3e57018c60012b3db3f"
}`
my method:
async myMethod(ids: [string], userId: string) {
try {
const { ok } = await this.ExpensesModel.updateMany(
{"userId": userId, "expenses.category": { $in: ids }},
{$set: {"expenses.$.category": "newCategoryID"}}
);
return ok
} ........
I path array of ids ["61f1cda47018c60012b3dd01","61f1cdb87018c60012b3dd07","61f1cdb87018c60012b3dd07"] and userId, this code update only 1 category by document.
So can i made it with mongo build in methods? or i need to find matching document and update it it by my self and after that update or insert;
Update with arrayFilters
db.collection.update({
"expenses.category": {
$in: [
"61f1cda47018c60012b3dd01",
"61f1cdb87018c60012b3dd07"
]
}
},
{
$set: {
"expenses.$[elem].category": "61eab3e57018c60012b3db3f"
}
},
{
arrayFilters: [
{
"elem.category": {
$in: [
"61f1cda47018c60012b3dd01",
"61f1cdb87018c60012b3dd07"
]
}
}
]
})
mongoplayground
I have a collection of mongodb like this :
[{
"_id":"ObjectId(""51780fb5c9c41825e3e21fc4"")",
"name":"CS 101",
"students":[
{
"name":"raj",
"year":2016
},
{
"name":"rahul",
"year":2017
},
{
"name":"anil",
"year":2018
}
]
},
{
"_id":"ObjectId(""51780fb5c9c41825e3e21fs4"")",
"name":"CS 102",
"students":[
{
"name":"mukesh",
"year":2016
},
{
"name":"mohan",
"year":2017
},
{
"name":"mangal",
"year":2018
}
]
}
]
I've been looking for similar questions like this one: Mongo db - Querying nested array and objects but in that question they're looking for a specific element inside the "messages" object (in my case) for example. Same as in this other question: Query for a field in an object in an array with Mongo? where they're using $mapan d I don't think it fits my needs.
The documents to find have this structure:
[{
"_id":"ObjectId(""51780fb5c9c41825e3e21fc4"")",
"name":"CS 101",
"students":[
"raj","rahul","anil"
]
},
{
"_id":"ObjectId(""51780fb5c9c41825e3e21fs4"")",
"name":"CS 102",
"students":[
"mukesh","mohan","mangal"
]
}
]
how to solve this?
From the question and datasets, you are trying to return students with an array of student's name (string) instead of the array of student object.
Use $project to display students as students.name array.
db.collection.aggregate([
{
$project: {
"_id": "$_id",
"name": "$name",
"students": "$students.name"
}
}
])
Sample Solution 1 on Mongo Playground
OR
Use $set to replace the students field with students.name array.
db.collection.aggregate([
{
$set: {
"students": "$students.name"
}
}
])
Sample Solution 2 on Mongo Playground
I currently have a problem where I have to update entries in a deeply nested Document. Now to simplify my problem I have this example. Let's assume I store cars in my MongoDB. A Document would look like this
{
Make: "BMW",
Model: "3Series",
Wheels: [
{
_id: someObjectId
Size: "19 inch",
Screws: [
{
_id: someObjectId
Type : "M15x40"
},
{
_id: someObjectId
Type : "M15x40"
}
]
}
]
}
Now if I want to update a specific Wheel, my code would look somewhat like this
CarModel.findOneAndUpdate({
"_id": CarId, "Wheels._id": WheelId
}, {
"$set" : {
"Wheels.$.Size": NewSize
}
})
Now this works. But I am pretty lost on how I would update an specific screw as I am going through 2 Arrays. Any Idea how I could make this work?
You need arrayFilters functionality to define the path for more than one nested array:
CarModel.findOneAndUpdate(
{ "_id": CarId },
{ $set: { "Wheels.$[wheel].Screws.$[screw].Type": "something" } },
{ arrayFilters: [ { 'wheel._id': WheelId }, { 'screw._id': screwId } ] })
I have documents that looks something like that, with a unique index on bars.name:
{ name: 'foo', bars: [ { name: 'qux', somefield: 1 } ] }
. I want to either update the sub-document where { name: 'foo', 'bars.name': 'qux' } and $set: { 'bars.$.somefield': 2 }, or create a new sub-document with { name: 'qux', somefield: 2 } under { name: 'foo' }.
Is it possible to do this using a single query with upsert, or will I have to issue two separate ones?
Related: 'upsert' in an embedded document (suggests to change the schema to have the sub-document identifier as the key, but this is from two years ago and I'm wondering if there are better solutions now.)
No there isn't really a better solution to this, so perhaps with an explanation.
Suppose you have a document in place that has the structure as you show:
{
"name": "foo",
"bars": [{
"name": "qux",
"somefield": 1
}]
}
If you do an update like this
db.foo.update(
{ "name": "foo", "bars.name": "qux" },
{ "$set": { "bars.$.somefield": 2 } },
{ "upsert": true }
)
Then all is fine because matching document was found. But if you change the value of "bars.name":
db.foo.update(
{ "name": "foo", "bars.name": "xyz" },
{ "$set": { "bars.$.somefield": 2 } },
{ "upsert": true }
)
Then you will get a failure. The only thing that has really changed here is that in MongoDB 2.6 and above the error is a little more succinct:
WriteResult({
"nMatched" : 0,
"nUpserted" : 0,
"nModified" : 0,
"writeError" : {
"code" : 16836,
"errmsg" : "The positional operator did not find the match needed from the query. Unexpanded update: bars.$.somefield"
}
})
That is better in some ways, but you really do not want to "upsert" anyway. What you want to do is add the element to the array where the "name" does not currently exist.
So what you really want is the "result" from the update attempt without the "upsert" flag to see if any documents were affected:
db.foo.update(
{ "name": "foo", "bars.name": "xyz" },
{ "$set": { "bars.$.somefield": 2 } }
)
Yielding in response:
WriteResult({ "nMatched" : 0, "nUpserted" : 0, "nModified" : 0 })
So when the modified documents are 0 then you know you want to issue the following update:
db.foo.update(
{ "name": "foo" },
{ "$push": { "bars": {
"name": "xyz",
"somefield": 2
}}
)
There really is no other way to do exactly what you want. As the additions to the array are not strictly a "set" type of operation, you cannot use $addToSet combined with the "bulk update" functionality there, so that you can "cascade" your update requests.
In this case it seems like you need to check the result, or otherwise accept reading the whole document and checking whether to update or insert a new array element in code.
if you dont mind changing the schema a bit and having a structure like so:
{ "name": "foo", "bars": { "qux": { "somefield": 1 },
"xyz": { "somefield": 2 },
}
}
You can perform your operations in one go.
Reiterating 'upsert' in an embedded document for completeness
I was digging for the same feature, and found that in version 4.2 or above, MongoDB provides a new feature called Update with aggregation pipeline.
This feature, if used with some other techniques, makes possible to achieve an upsert subdocument operation with a single query.
It's a very verbose query, but I believe if you know that you won't have too many records on the subCollection, it's viable. Here's an example on how to achieve this:
const documentQuery = { _id: '123' }
const subDocumentToUpsert = { name: 'xyz', id: '1' }
collection.update(documentQuery, [
{
$set: {
sub_documents: {
$cond: {
if: { $not: ['$sub_documents'] },
then: [subDocumentToUpsert],
else: {
$cond: {
if: { $in: [subDocumentToUpsert.id, '$sub_documents.id'] },
then: {
$map: {
input: '$sub_documents',
as: 'sub_document',
in: {
$cond: {
if: { $eq: ['$$sub_document.id', subDocumentToUpsert.id] },
then: subDocumentToUpsert,
else: '$$sub_document',
},
},
},
},
else: { $concatArrays: ['$sub_documents', [subDocumentToUpsert]] },
},
},
},
},
},
},
])
There's a way to do it in two queries - but it will still work in a bulkWrite.
This is relevant because in my case not being able to batch it is the biggest hangup. With this solution, you don't need to collect the result of the first query, which allows you to do bulk operations if you need to.
Here are the two successive queries to run for your example:
// Update subdocument if existing
collection.updateMany({
name: 'foo', 'bars.name': 'qux'
}, {
$set: {
'bars.$.somefield': 2
}
})
// Insert subdocument otherwise
collection.updateMany({
name: 'foo', $not: {'bars.name': 'qux' }
}, {
$push: {
bars: {
somefield: 2, name: 'qux'
}
}
})
This also has the added benefit of not having corrupted data / race conditions if multiple applications are writing to the database concurrently. You won't risk ending up with two bars: {somefield: 2, name: 'qux'} subdocuments in your document if two applications run the same queries at the same time.