{
id: 1,
name: "sree",
userId: "001",
paymentData: {
user_Id: "001",
amount: 200
}
},
{
id: 1,
name: "sree",
userId: "001",
paymentData: {
user_Id: "002",
amount: 200
}
}
I got this result after unwind in aggregation any way to check user_Id equal to userId
Are you looking to only retrieve the results when they are equal (meaning you want to filter out documents where the values are not the same) or are you looking to add a field indicating whether the two are equal?
In either case, you append subsequent stage(s) to the aggregation pipeline to achieve your desired result. If you want to filter the documents, the new stage may be:
{
$match: {
$expr: {
$eq: [
"$userId",
"$paymentData.user_Id"
]
}
}
}
See how it works in this playground example.
If instead you want to add a field that compares the two values, then this stage may be what you are looking for:
{
$addFields: {
isEqual: {
$eq: [
"$userId",
"$paymentData.user_Id"
]
}
}
}
See how it works in this playground example.
You could also combine the two as in:
{
$addFields: {
isEqual: {
$eq: [
"$userId",
"$paymentData.user_Id"
]
}
}
},
{
$match: {
isEqual: true
}
}
Playground demonstration here
I have the following sample of data:
{
_id: 1,
seniorityDate: '2001-01-01T00:00:00Z',
assigned: [
{
groupId: 11,
system: 'Dep',
effectiveDate: null
},
{
groupId: 12,
system: 'Team',
effectiveDate: null
},
...
]
}
and I would like to update the object effectiveDate based on seniorityDate in the array of assigned where system:'Team' only:
db.collection.updateMany({},
[{
$set: {
'assigned.$[elem].effectiveDate': '$seniorityDate'
}
}], {
arrayFilters: [{
"elem.system": "Team"
}]
})
but I got the following error:
arrayFilters may not be specified for pipeline-syle updates
The expected result will be:
{
_id: 1,
seniorityDate: '2001-01-01T00:00:00Z',
assigned: [
{
groupId: 11,
system: 'Dep',
effectiveDate: null
},
{
groupId: 12,
system: 'Team',
effectiveDate: '2001-01-01T00:00:00Z'
},
...
]
}
How can I achieve it?
You can't use the arrayFilters with the aggregation pipeline at the same time. While you are updating the value from another field, hence you can only achieve with aggregation pipeline.
$set - Set assigned field.
1.1. $map - Iterate element in assigned array and return new array.
1.1.1. $mergeObjects - Merge current iterated document with the document from 1.1.1.1.
1.1.1.1. Document with effectiveDate field. With the $cond operator, if matches the condition, use the seniorityDate value, else remain the existing value.
db.collection.updateMany({},
[
{
$set: {
"assigned": {
$map: {
input: "$assigned",
in: {
$mergeObjects: [
"$$this",
{
effectiveDate: {
$cond: {
if: {
$eq: [
"$$this.system",
"Team"
]
},
then: "$seniorityDate",
else: "$$this.effectiveDate"
}
}
}
]
}
}
}
}
}
])
Thanks to #rickhg12hs' suggestion, always limit the document for better performance, as you know which document/field should be updated by condition.
Hence your update query with query condition will be as below:
db.collection.updateMany({
"assigned.system": "Team"
},
[
...
])
Demo # Mongo Playground
I have an issue that need to insert index number when get data. First i have this data for example:
[
{
_id : 616efd7e56c9530018e318ac
student : {
name: "Alpha"
email: null
nisn: "0408210001"
gender : "female"
}
},
{
_id : 616efd7e56c9530018e318af
student : {
name: "Beta"
email: null
nisn: "0408210001"
gender : "male"
}
}
]
and then i need the output like this one:
[
{
no:1,
id:616efd7e56c9530018e318ac,
name: "Alpha",
nisn: "0408210001"
},
{
no:2,
id:616efd7e56c9530018e318ac,
name: "Beta",
nisn: "0408210002"
}
]
i have tried this code but almost get what i expected.
{
'$project': {
'_id': 0,
'id': '$_id',
'name': '$student.name',
'nisn': '$student.nisn'
}
}
but still confuse how to add the number of index. Is it available to do it in $project or i have to do it other way? Thank you for the effort to answer.
You can use $unwind which can return an index, like this:
db.collection.aggregate([
{
$group: {
_id: 0,
data: {
$push: {
_id: "$_id",
student: "$student"
}
}
}
},
{
$unwind: {path: "$data", includeArrayIndex: "no"}
},
{
"$project": {
"_id": 0,
"id": "$data._id",
"name": "$data.student.name",
"nisn": "$data.student.nisn",
"no": {"$add": ["$no", 1] }
}
}
])
You can see it works here .
I strongly suggest to use a $match step before these steps, otherwise you will group your entire collection into one document.
You need to run a pipeline with a $setWindowFields stage that allows you to add a new field which returns the position of a document (known as the document number) within a partition. The position number creation is made possible by the $documentNumber operator only available in the $setWindowFields stage.
The partition could be an extra field (which is constant) that can act as the window partition.
The final stage in the pipeline is the $replaceWith step which will promote the student embedded document to the top-level as well as replacing all input documents with the specified document.
Running the following aggregation will yield the desired results:
db.collection.aggregate([
{ $addFields: { _partition: 'students' }},
{ $setWindowFields: {
partitionBy: '$_partition',
sortBy: { _id: -1 },
output: { no: { $documentNumber: {} } }
} },
{ $replaceWith: {
$mergeObjects: [
{ id: '$_id', no: '$no' },
'$student'
]
} }
])
I recently updated my subschemas (called Courses) to have timestamps and am trying to backfill existing documents to include createdAt/updatedAt fields.
Courses are stored in an array called courses in the user document.
// User document example
{
name: "Joe John",
age: 20,
courses: [
{
_id: <id here>,
name: "Intro to Geography",
units: 4
} // Trying to add timestamps to each course
]
}
I would also like to derive the createdAt field from the Course's Mongo ID.
This is the code I'm using to attempt adding the timestamps to the subdocuments:
db.collection('user').updateMany(
{
'courses.0': { $exists: true },
},
{
$set: {
'courses.$[elem].createdAt': { $toDate: 'courses.$[elem]._id' },
},
},
{ arrayFilters: [{ 'elem.createdAt': { $exists: false } }] }
);
However, after running the code, no fields are added to the Course subdocuments.
I'm using mongo ^4.1.1 and mongoose ^6.0.6.
Any help would be appreciated!
Using aggregation operators and referencing the value of another field in an update statement requires using the pipeline form of update, which is not available until MongoDB 4.2.
Once you upgrade, you could use an update like this:
db.collection.updateMany({
"courses": {$elemMatch: {
_id:{$exists:true},
createdAt: {$exists: false}
}}
},
[{$set: {
"courses": {
$map: {
input: "$courses",
in: {
$mergeObjects: [
{createdAt: {
$convert: {
input: "$$this._id",
to: "date",
onError: {"error": "$$this._id"}
}
}},
"$$this"
]
}
}
}
}
}
])
I have the following collection
{
"_id" : ObjectId("57315ba4846dd82425ca2408"),
"myarray" : [
{
userId : ObjectId("570ca5e48dbe673802c2d035"),
point : 5
},
{
userId : ObjectId("613ca5e48dbe673802c2d521"),
point : 2
},
]
}
These are my questions
I want to push into myarray if userId doesn't exist, it should be appended to myarray. If userId exists, it should be updated to point.
I found this
db.collection.update({
_id : ObjectId("57315ba4846dd82425ca2408"),
"myarray.userId" : ObjectId("570ca5e48dbe673802c2d035")
}, {
$set: { "myarray.$.point": 10 }
})
But if userId doesn't exist, nothing happens.
and
db.collection.update({
_id : ObjectId("57315ba4846dd82425ca2408")
}, {
$push: {
"myarray": {
userId: ObjectId("570ca5e48dbe673802c2d035"),
point: 10
}
}
})
But if userId object already exists, it will push again.
What is the best way to do this in MongoDB?
Try this
db.collection.update(
{ _id : ObjectId("57315ba4846dd82425ca2408")},
{ $pull: {"myarray.userId": ObjectId("570ca5e48dbe673802c2d035")}}
)
db.collection.update(
{ _id : ObjectId("57315ba4846dd82425ca2408")},
{ $push: {"myarray": {
userId:ObjectId("570ca5e48dbe673802c2d035"),
point: 10
}}
)
Explination:
in the first statment $pull removes the element with userId= ObjectId("570ca5e48dbe673802c2d035") from the array on the document where _id = ObjectId("57315ba4846dd82425ca2408")
In the second one $push inserts
this object { userId:ObjectId("570ca5e48dbe673802c2d035"), point: 10 } in the same array.
The accepted answer by Flying Fisher is that the existing record will first be deleted, and then it will be pushed again.
A safer approach (common sense) would be to try to update the record first, and if that did not find a match, insert it, like so:
// first try to overwrite existing value
var result = db.collection.update(
{
_id : ObjectId("57315ba4846dd82425ca2408"),
"myarray.userId": ObjectId("570ca5e48dbe673802c2d035")
},
{
$set: {"myarray.$.point": {point: 10}}
}
);
// you probably need to modify the following if-statement to some async callback
// checking depending on your server-side code and mongodb-driver
if(!result.nMatched)
{
// record not found, so create a new entry
// this can be done using $addToSet:
db.collection.update(
{
_id: ObjectId("57315ba4846dd82425ca2408")
},
{
$addToSet: {
myarray: {
userId: ObjectId("570ca5e48dbe673802c2d035"),
point: 10
}
}
}
);
// OR (the equivalent) using $push:
db.collection.update(
{
_id: ObjectId("57315ba4846dd82425ca2408"),
"myarray.userId": {$ne: ObjectId("570ca5e48dbe673802c2d035"}}
},
{
$push: {
myarray: {
userId: ObjectId("570ca5e48dbe673802c2d035"),
point: 10
}
}
}
);
}
This should also give (common sense, untested) an increase in performance, if in most cases the record already exists, only the first query will be executed.
There is a option called update documents with aggregation pipeline starting from MongoDB v4.2,
check condition $cond if userId in myarray.userId or not
if yes then $map to iterate loop of myarray array and check condition if userId match then merge with new document using $mergeObjects
if no then $concatArrays to concat new object and myarray
let _id = ObjectId("57315ba4846dd82425ca2408");
let updateDoc = {
userId: ObjectId("570ca5e48dbe673802c2d035"),
point: 10
};
db.collection.update(
{ _id: _id },
[{
$set: {
myarray: {
$cond: [
{ $in: [updateDoc.userId, "$myarray.userId"] },
{
$map: {
input: "$myarray",
in: {
$mergeObjects: [
"$$this",
{
$cond: [
{ $eq: ["$$this.userId", updateDoc.userId] },
updateDoc,
{}
]
}
]
}
}
},
{ $concatArrays: ["$myarray", [updateDoc]] }
]
}
}
}]
)
Playground
Unfortunately "upsert" operation is not possible on embedded array. Operators simply do not exist so that this is not possible in a single statement.Hence you must perform two update operations in order to do what you want. Also the order of application for these two updates is important to get desired result.
I haven't found any solutions based on a one atomic query. Instead there are 3 ways based on a sequence of two queries:
always $pull (to remove the item from array), then $push (to add the updated item to array)
db.collection.update(
{ _id : ObjectId("57315ba4846dd82425ca2408")},
{ $pull: {"myarray.userId": ObjectId("570ca5e48dbe673802c2d035")}}
)
db.collection.update(
{ _id : ObjectId("57315ba4846dd82425ca2408")},
{
$push: {
"myarray": {
userId:ObjectId("570ca5e48dbe673802c2d035"),
point: 10
}
}
}
)
try to $set (to update the item in array if exists), then get the result and check if the updating operation successed or if a $push needs (to insert the item)
var result = db.collection.update(
{
_id : ObjectId("57315ba4846dd82425ca2408"),
"myarray.userId": ObjectId("570ca5e48dbe673802c2d035")
},
{
$set: {"myarray.$.point": {point: 10}}
}
);
if(!result.nMatched){
db.collection.update({_id: ObjectId("57315ba4846dd82425ca2408")},
{
$addToSet: {
myarray: {
userId: ObjectId("570ca5e48dbe673802c2d035"),
point: 10
}
}
);
always $addToSet (to add the item if not exists), then always $set to update the item in array
db.collection.update({_id: ObjectId("57315ba4846dd82425ca2408")},
myarray: { $not: { $elemMatch: {userId: ObjectId("570ca5e48dbe673802c2d035")} } } },
{
$addToSet : {
myarray: {
userId: ObjectId("570ca5e48dbe673802c2d035"),
point: 10
}
}
},
{ multi: false, upsert: false});
db.collection.update({
_id: ObjectId("57315ba4846dd82425ca2408"),
"myArray.userId": ObjectId("570ca5e48dbe673802c2d035")
},
{ $set : { myArray.$.point: 10 } },
{ multi: false, upsert: false});
1st and 2nd way are unsafe, so transaction must be established to avoid two concurrent requests could push the same item generating a duplicate.
3rd way is safer. the $addToSet adds only if the item doesn't exist, otherwise nothing happens. In case of two concurrent requests, only one of them adds the missing item to the array.
Possible solution with aggregation pipeline:
db.collection.update(
{ _id },
[
{
$set: {
myarray: { $filter: {
input: '$myarray',
as: 'myarray',
cond: { $ne: ['$$myarray.userId', ObjectId('570ca5e48dbe673802c2d035')] },
} },
},
},
{
$set: {
myarray: {
$concatArrays: [
'$myarray',
[{ userId: ObjectId('570ca5e48dbe673802c2d035'), point: 10 },
],
],
},
},
},
],
);
We use 2 stages:
filter myarray (= remove element if userId exist)
concat filtered myarray with new element;
When you want update or insert value in array try it
Object in db
key:name,
key1:name1,
arr:[
{
val:1,
val2:1
}
]
Query
var query = {
$inc:{
"arr.0.val": 2,
"arr.0.val2": 2
}
}
.updateOne( { "key": name }, query, { upsert: true }
key:name,
key1:name1,
arr:[
{
val:3,
val2:3
}
]
In MongoDB 3.6 it is now possible to upsert elements in an array.
array update and create don't mix in under one query, if you care much about atomicity then there's this solution:
normalise your schema to,
{
"_id" : ObjectId("57315ba4846dd82425ca2408"),
userId : ObjectId("570ca5e48dbe673802c2d035"),
point : 5
}
You could use a variation of the .forEach/.updateOne method I currently use in mongosh CLI to do things like that. In the .forEach, you might be able to set all of your if/then conditions that you mentioned.
Example of .forEach/.updateOne:
let medications = db.medications.aggregate([
{$match: {patient_id: {$exists: true}}}
]).toArray();
medications.forEach(med => {
try {
db.patients.updateOne({patient_id: med.patient_id},
{$push: {medications: med}}
)
} catch {
console.log("Didn't find match for patient_id. Could not add this med to a patient.")
}
})
This may not be the most "MongoDB way" to do it, but it definitely works and gives you the freedom of javascript to do things within the .forEach.