I need to use integer numbers for my array object ID. now in mongoDB the default _id for array objects are ObjectId('62e10eb9150cd328edd6f6y3') and i need to change that to integer numbers. Can I know is that possible or not. If that possible please mention how to do that.
now in mongoDB the default _id for array objects are ObjectId('62e10eb9150cd328edd6f6y3')
This is not true, this is true for mongoose as it generates an ObjectId for each object by default - but this is not a MongoDB feature.
mongoose does not offer any alternatives as a feature, in your case using index of array as _id, but you can work around it by executing a slightly less efficient update using the aggregation pipeline syntax, like so:
const newArrayItem = { ... new array items };
db.collection.updateOne(
{},
[
{
"$set": {
"items": {
$concatArrays: [
{
$ifNull: [
"$items",
[]
]
},
[
{
$mergeObjects: [
newArrayItem,
{
_id: {
$size: {
$ifNull: [
"$items",
[]
]
}
}
}
]
}
]
]
}
}
}
])
Mongo Playground
Related
Array field in collection:
"fruits": [ "fruits": [ "fruits": [
{"fruit1": "banana"}, {"fruit2": "apple"}, {"fruit3": "pear"},
{"fruit2": "apple"}, {"fruit4": "orange"}, {"fruit2": "apple"},
{"fruit3": "pear"}, {"fruit1": "banana"}, {"fruit4": "orange"},
{"fruit4": "orange"} {"fruit3": "pear"} {"fruit1": "banana"}
]
I need to find those documents in collections, where "banana" signed before "apple". Does mongodb allows to compare elements in array just like :
if (fruits.indexOf('banana') < fruits.indexOf('apple')) return true;
Or maybe there is any other method to get result i need?
MongoDB's array query operations do not support any positional search as you want.
You can, however, write a $where query to do what you want:
db.yourCollection.find({
$where: function() {
return (this.fruits.indexOf('banana') < this.fruits.indexOf('apple'))
}
})
Be advised though, you won't be able to use indexes here and the performance will be a problem.
Another approach you can take is to rethink the database design, if you can specify what it is you're trying to build, someone can give you specific advise.
One more approach: pre-calculate the boolean value before persisting to DB as a field and query on true / false.
Consider refactoring your schema if possible. The dynamic field names(i.e. fruit1, fruit2...) make it unnecessarily complicated to construct a query. Also, if you require frequent queries by array index, you should probably store your array entries in individual documents with some sort keys to facilitate sorting with index.
Nevertheless, it is achievable through $unwind and $group the documents again. With includeArrayIndex clause, you can get the index inside array.
db.collection.aggregate([
{
"$unwind": {
path: "$fruits",
includeArrayIndex: "idx"
}
},
{
"$addFields": {
fruits: {
"$objectToArray": "$fruits"
}
}
},
{
"$addFields": {
"bananaIdx": {
"$cond": {
"if": {
$eq: [
"banana",
{
$first: "$fruits.v"
}
]
},
"then": "$idx",
"else": "$$REMOVE"
}
},
"appleIdx": {
"$cond": {
"if": {
$eq: [
"apple",
{
$first: "$fruits.v"
}
]
},
"then": "$idx",
"else": "$$REMOVE"
}
}
}
},
{
$group: {
_id: "$_id",
fruits: {
$push: {
"$arrayToObject": "$fruits"
}
},
bananaIdx: {
$max: "$bananaIdx"
},
appleIdx: {
$max: "$appleIdx"
}
}
},
{
$match: {
$expr: {
$lt: [
"$bananaIdx",
"$appleIdx"
]
}
}
},
{
$unset: [
"bananaIdx",
"appleIdx"
]
}
])
Mongo Playground
My question is a combination of:
This question: Removing the array element in mongoDB based on the position of element
And this question: mongodb set object where key value dynamically changes
I know you can define the field (array) dynamically like this:
{ [arrayName]: { <condition> } }
But, I then want to remove a certain element in a dynamically defined array by specifying the position (which is also defined dynamically). In other words, the function that processes this query is coming in which two parameters: the array's name and the index of the element to remove.
The options given by the selected answer were the following:
Option 1, does not work (in general), adapted to my case this looks like:
{ $pull : { [arrayName] : { $gt: index-1, $lt: index+1 } } }
Option 2, I cannot use dynamically defined values in field selectors with quotation marks (as far as I am aware):
{ $pull : "[arrayName].[index]" }
or
{ $pull : "[arrayName].$": index }
Option 3, is different method but can't use it for the same reason:
{ $unset: { "[arrayName].[index]": 1 } } // Won't work
{ $pull: { [arrayName]: null } } // Would probably work
The only workarounds I can think of right now involve significantly changing the design which would be a shame. Any help is appreciated!
PS: I'm using mongoose as a driver on the latest version as of today (v6.3.5) and MongoDB version 5.0.8
On Mongo version 4.2+ You can use pipelined updates to achieve this, you can get it done in multiple ways, here is what I consider the easiest two ways:
using $slice and $concatArrays to remove a certain element:
db.collection.update({},
[
{
$set: {
[arrayName]: {
$concatArrays: [
{
$slice: [
`$${arrayName}`,
index,
]
},
{
$slice: [
`$${arrayName}`,
index + 1,
{
$size: `$${arrayName}`
}
]
}
]
}
}
}
])
Mongo Playground
using $filter and $zip to filter out based on index:
db.collection.updateOne(
{},
[
{
"$set": {
[arrayName]: {
$map: {
input: {
$filter: {
input: {
$zip: {
inputs: [
{
$range: [
0,
{
$size: `$${arrayName}`
}
]
},
`$${arrayName}`
]
}
},
cond: {
$ne: [
{
"$arrayElemAt": [
"$$this",
0
]
},
index
]
}
}
},
in: {
$arrayElemAt: [
"$$this",
1
]
}
}
}
}
}
])
Alternatively you can just prepare
MongoDB: 4.4.9, Mongosh: 1.0.4
I have a MongoDB collection full of documents with monthly production data as separate fields (monthlyProd1, monthlyProd2, etc.). Each field is one month's production data, and the values are an object data type.
Document example:
_id: ObjectId("314e0e088f183fb7e699d635")
name: "documentName"
monthlyProd1: Object
monthlyProd2: Object
monthlyProd3: Object
...
I want to take all the months and put them into a single new field (monthlyProd) -- a single array of objects.
I can't seem to access the fields with the different methods I've tried. For example, this gets close to doing what I want:
db.monthlyProdData.updateMany({},
{ $push: { "monthlyProd": { $each: [ "$monthlyProd1", "$monthlyProd2", "$monthlyProd3" ] } } }
)
...but instead of taking the value / object data from each field, like I had hoped, it just outputs a string into the monthlyProd array ("$monthlyProd1", "$monthlyProd2", ...):
Actual output:
monthlyProd: Array
0: "$monthlyProd1"
1: "$monthlyProd2"
2: "$monthlyProd3"
...
Desired output:
monthlyProd: Array
0: Object
1: Object
2: Object
...
I want the data, not a string! Lol. Thank you for your help!
Note: some months/fields may be an empty string ("") because there was no production. I want to make sure to not add empty strings into the array -- only months with production / fields that have an object data type. That being said, I can try figuring that out on my own, if I can just get access to these fields' data!
Try this one:
db.collection.updateMany({}, [
// convert to k-v Array
{ $set: { monthlyProd: { $objectToArray: "$$ROOT" } } },
{
$set: {
monthlyProd: {
// removed not needed objects
$filter: {
input: "$monthlyProd",
cond: { $not: { $in: [ "$$this.k", [ "name", "_id" ] ] } }
// or cond: { $in: [ "$$this.k", [ "monthlyProd1", "monthlyProd2", "monthlyProd3" ] ] }
}
}
}
},
// output array value
{ $project: { monthlyProd: "$monthlyProd.v" } }
])
Mongo playground
Thank you to #Wernfried for the original solution to this question. I have modified the solution to incorporate my "Note" about ignoring any empty monthlyProd# values (aka months that didn't have any production), so that they are not added into the final monthlyProd array.
To do this, I added an $and operator to the cond: within $filter, and added the following as the second expression for the $and operator (I used "" and {} to take care of the empty field values if they are of either string or object data type):
{ $not: { $in: [ "$$this.v", [ "", {} ] ] } }
Final solution:
db.monthlyProdData2.updateMany({}, [
// convert to k-v Array
{ $set: { monthlyProd: { $objectToArray: "$$ROOT" } } },
{
$set: {
monthlyProd: {
// removed not needed objects
$filter: {
input: "$monthlyProd",
cond: { $and: [
{ $not: { $in: [ "$$this.k", [ "name", "_id" ] ] } },
{ $not: { $in: [ "$$this.v", [ "", {} ] ] } }
]}
}
}
}
},
// output array value
{ $project: { monthlyProd: "$monthlyProd.v", name: 1 } }
])
Thanks again #Wernfried and Stackoverflow community!
I need to check if an ObjectId exists in a non nested array and in multiple nested arrays, I've managed to get very close using the aggregation framework, but got stuck in the very last step.
My documents have this structure:
{
"_id" : ObjectId("605ce5f063b1c2eb384c2b7f"),
"name" : "Test",
"attrs" : [
ObjectId("6058e94c3994d04d28639616"),
ObjectId("6058e94c3994d04d28639627"),
ObjectId("6058e94c3994d04d28639622"),
ObjectId("6058e94c3994d04d2863962e")
],
"variations" : [
{
"varName" : "Var1",
"attrs" : [
ObjectId("6058e94c3994d04d28639616"),
ObjectId("6058e94c3994d04d28639627"),
ObjectId("6058e94c3994d04d28639622"),
ObjectId("60591791d4d41d0a6817d23f")
],
},
{
"varName" : "Var2",
"attrs" : [
ObjectId("60591791d4d41d0a6817d22a"),
ObjectId("60591791d4d41d0a6817d255"),
ObjectId("6058e94c3994d04d28639622"),
ObjectId("60591791d4d41d0a6817d23f")
],
},
],
"storeId" : "9acdq9zgke49pw85"
}
Let´s say I need to check if this if this _id exists "6058e94c3994d04d28639616" in all arrays named attrs.
My aggregation query goes like this:
db.product.aggregate([
{
$match: {
storeId,
},
},
{
$project: {
_id: 0,
attrs: 1,
'variations.attrs': 1,
},
},
{
$project: {
attrs: 1,
vars: '$variations.attrs',
},
},
{
$unwind: '$vars',
},
{
$project: {
attr: {
$concatArrays: ['$vars', '$attrs'],
},
},
},
]);
which results in this:
[
{
attr: [
6058e94c3994d04d28639616,
6058e94c3994d04d28639627,
6058e94c3994d04d28639622,
6058e94c3994d04d2863962e,
6058e94c3994d04d28639616,
6058e94c3994d04d28639627,
6058e94c3994d04d28639622,
60591791d4d41d0a6817d23f,
60591791d4d41d0a6817d22a,
60591791d4d41d0a6817d255,
6058e94c3994d04d28639622,
60591791d4d41d0a6817d23f
]
},
{
attr: [
60591791d4d41d0a6817d22a,
60591791d4d41d0a6817d255,
6058e94c3994d04d28639622,
60591791d4d41d0a6817d23f,
6058e94c3994d04d28639624,
6058e94c3994d04d28639627,
6058e94c3994d04d28639628,
6058e94c3994d04d2863963e
]
}
]
Assuming I have two products in my DB, I get this result. Each element in the outermost array is a different product.
The last bit, which is checking for this key "6058e94c3994d04d28639616", I could not find a way to do it with $group, since I dont have keys to group on.
Or with $match, adding this to the end of the aggregation:
{
$match: {
attr: "6058e94c3994d04d28639616",
},
},
But that results in an empty array. I know that $match does not query arrays like this, but could not find a way to do it with $in as well.
Is this too complicated of a Schema? I cannot have the original data embedded, since it is mutable and I would not be happy to change all products if something changed.
Will this be very expensive if I had like 10000 products?
Thanks in advance
You are trying to compare string 6058e94c3994d04d28639616 with ObjectId. Convert the string to ObjectId using $toObjectId operator when perform $match operation like this:
{
$match: {
$expr: {
$in: [{ $toObjectId: "6058e94c3994d04d28639616" }, "$attr"]
}
}
}
How to check if all values in an array are the same mongodb aggregation? Say I have an array ["a","a","a","a","a"] in an aggregation stage. How do I check if all the values are the same using mongodb aggregation?
And if there is a different approach for an array of objects [{a:"a",b:"b"},{a:"c",b:"d"}]. How do I check if all the values of a given object property are the same for all objects in an array using mongodb aggregation?
I know in javascript I can use array.every() is there an equivalent in mongodb?
You can try using $allElementsTrue:
db.collection.aggregate([
{
$project: {
areSame: {
$allElementsTrue: {
$map: {
input: "$key",
in: {
$eq: [ "$$this", { $arrayElemAt: [ "$key", 0 ] } ]
}
}
}
}
}
}
])
Mongo Playground
same solution should work for objects