I have an array of numbers. I'd like to compare each item in the array to all the values for a particular key of a collection. Is that possible? In the example below, I'd grab only those objects that have an id of 05,07,21,36,and 42.. but this attempt fails -
var playlist =[05,07,21,36,42]
The query:
Track.find({ id: playlist })...
The collection:
artist:{type: String},
title: {type: String},
id: {type: String}...
The property is actually "_id" -- Track.find({ "_id": {$in: playlist} }) -- and when I tried this, I was returned the error printed below. Any ideas?
message: 'Cast to ObjectId failed for value "597e2f68c83f5d5ba6723427,597e2f68c83f5d5ba6723429,597e2f68c83f5d5ba672342c,597e2f68c83f5d5ba6723429,597e2f68c83f5d5ba672342c,597e2f68c83f5d5ba672342b,597e2f68c83f5d5ba672342d" at path "_id" for model "Track"',
name: 'CastError',
stringValue: '"597e2f68c83f5d5ba6723427,597e2f68c83f5d5ba6723429,597e2f68c83f5d5ba672342c,597e2f68c83f5d5ba6723429,597e2f68c83f5d5ba672342c,597e2f68c83f5d5ba672342b,597e2f68c83f5d5ba672342d"',
kind: 'ObjectId',
value: '597e2f68c83f5d5ba6723427,597e2f68c83f5d5ba6723429,597e2f68c83f5d5ba672342c,597e2f68c83f5d5ba6723429,597e2f68c83f5d5ba672342c,597e2f68c83f5d5ba672342b,597e2f68c83f5d5ba672342d',
path: '_id',
You need to use $in. Try Track.find({ id: { $in: playlist } })
See Mongo $in Operator
Related
I'd like to be able to pull a document by id from a triple nested array of documents. DB looks something like this:
[{
type: "Foods",
fruit: [{
name: "Apple",
kinds: [{
name: "Red Delicious"
details: [{
_id: ObjectId("123123123"),
colors: ["red", "yellow"]
}]
}]
}]
}]
I'd like to be able to pull the document with the _id: 123123123. I've tried many different ways, but it always says it matches, but won't modify the document.
I've tried:
db.stuff.update({}, {$pull: {fruits: {kinds: {details: {_id: "123123123"}}}}}),
db.stuff.update({}, {$pull: {"fruits.kinds.details' : {_id: "123123123"}}}),
db.stuff.update({}, {$pull: {"fruits.$[].kinds.$[].details' : {_id: "123123123"}}})
But everytime it matches, but won't delete the document.
Please help.
The last attempt is correct however you need to fix two things: fruit instead of fruit (according to your sample data) and types needs to match so you have to convert string to ObjectId
db.stuff.update({}, {$pull: {"fruit.$[].kinds.$[].details' : {_id: mongoose.Types.ObjectId("123123123")}}})
I have the following schema:
var lessonSchema = mongoose.Schema({
_id: mongoose.Schema.Types.ObjectId,
name: String,
students: [{
_id: mongoose.Schema.Types.ObjectId,
attendance: {
type: Boolean,
default: false,
},
}],
});
The students array is an array of students who attended the particular lesson. I want to find a lesson using whether a particular user is present in the students array and then sent only that element of the students array which corresponds to the user making the request, along with all other fields as it is. For example, the query should return:
{
_id: 'objectid',
name: 'lesson-name'
students: [details of just the one student corresponding to req.user._id]
}
I tried using:
Lesson.find({'students._id': String(req.user._id)}, {"students.$": 1})
The query returns the document with just the id and the relevant element from the students array:
{
_id: 'objectid'
students: [details of the one student corresponding to req.user._id]
}
I tried using:
Lesson.find({'students._id': mongoose.Types.ObjectId(req.user._id)})
This returns the document with the details of all the students:
{
_id: 'objectid',
name: 'lesson-name'
students: [array containing details of all the students who attended the lesson]
}
How can I modify the query to return it the way I want?
You can return the name field by adding it to the projection object like this:
Lesson.find({ "students._id": String(req.user._id) }, { "name": 1, "students.$": 1 })
When you add a projection object (2nd parameter to find), the _id field is returned by default, plus whichever fields you set to 1.
Therefore, you were returning just the _id and the desired student but not the name field.
If you want to return all other fields and just limit the array to the matched item then you can make use of $slice in your projection:
Lesson.find({ "students._id": String(req.user._id) }, { "students.$": { $slice: 1 } })
I have a model like this:
[{item: {
_id: 123,
field1: someValue,
price: {
[_id: 456,
field1: anotherValue,
type: []],
[_id: 789,
field1: anotherValue,
type: ['super']]
}
}]
I need to find an item by 3 parameters: item _id, price _id, and check if price type array is empty. And check it in one price field.
Model.findOneAndUpdate({_id: 123, "price._id": 456, "price.type": {size:0})
This query always returns item, cause search in different prices.
Model.findOneAndUpdate({_id: 123, price: {id: 456, type: {size:0})
This query returns error (cast array value or something like this).
tried to build query with $in, $and, but still getting an error
Use $elemMatch:
The $elemMatch operator matches documents that contain an array field
with at least one element that matches all the specified query
criteria.
db.inventory.find({
price: {
"$elemMatch": {
_id: 456,
type: {
$size: 0
}
}
}
})
I'm trying to get all documents in a collection based on a subdocument array values. This is my data structure in the collection i'm seeking:
{
_id: ObjectId('...'),
name: "my event",
members:
[
{
_id: ObjectId('...'),
name: "family",
users: [ObjectId('...'),ObjectId('...'),ObjectId('...')]
},
{
_id: ObjectId('...'),
name: "work",
users: [ObjectId('...'),ObjectId('...'),ObjectId('...')]
}
]
}
I should point out that the schema of these objects are defined like so:
Events:
{
name: { type: String },
members: {type: [{ type: ObjectId, ref: 'MemberGroup' }], default:[] }
}
MemberGroup:
{
name: { type: String },
users: [{type: mongoose.Schema.Types.ObjectId, ref: 'User'}]
}
and of course User is just an arbitrary object with an id.
What i'm trying to fetch: i want to retrieve all events which has a specific user id in its member.users field.
i'm not sure if its event possible in a single call but here is what i've tried:
var userId = new mongoose.Schema.ObjectId('57d9503ef10d5ffc08d6b8cc');
events.find({members: { $elemMatch : { users: { $in: [userId]} } }})
this syntax work but return no elements even though i know there are matching elements (using robomongo to visualize the db)
So after a long search in stackoverflow i came across the good answare here:
MongoDB: How to find out if an array field contains an element?
my query changed to the following which gave me my desired result:
var userId = new mongoose.Schema.ObjectId('57d9503ef10d5ffc08d6b8cc');
events.find({}, {members: { $elemMatch : { users: { $eq: userId} } }})
notice the use of the second find parameter to specify the query limit instead of the first one (which is odd)
I'm a new user of mongodb and I have a model like below. For update list data, I have to specify the element in an array. So I think I need to store a unique value for each element. Because list.name and list.price are variable data.
So are there any good ways to create an unique id in mongodb? Or should I create unique ids by myself?
{
name: 'AAA',
list: [
{name: 'HOGE', price: 10, id: 'XXXXXXXXXX'}, // way to add id
{name: 'FUGA', price: 12, id: 'YYYYYYYYYY'} // way to add id
]
}
Mongodb creates unique id only for documents. There is no better way for list or array elements. So, you should create Unique ids yourself.
Add keep in mind that, While updating your list use $addToSet.
For more information of $addToSet follow this documentation
use ObjectId() on your id field, so like..
db.test.update({name: "AAA"}, { $push: { list: {_id : ObjectId(), name: "dingles", price: 21} }});
reference: https://docs.mongodb.org/v3.0/reference/object-id/
whoever is seeing this in 2022, mongodb creates unique ids automatically we just have to provide schema for that particular array.
like,
_id : {
type: String
},
list: {
type: [{
Name : {
type: String
},
price : {
type: String
}
}]
}
this schema will generate auto id for all elements added into array
but below example will not create it.
_id : {
type: String
},
list: {
type: Array
}