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Mongoose search for items on array containing _id with aggregate [duplicate]

If I have this schema...
person = {
name : String,
favoriteFoods : Array
}
... where the favoriteFoods array is populated with strings. How can I find all persons that have "sushi" as their favorite food using mongoose?
I was hoping for something along the lines of:
PersonModel.find({ favoriteFoods : { $contains : "sushi" }, function(...) {...});
(I know that there is no $contains in mongodb, just explaining what I was expecting to find before knowing the solution)

As favouriteFoods is a simple array of strings, you can just query that field directly:
PersonModel.find({ favouriteFoods: "sushi" }, ...); // favouriteFoods contains "sushi"
But I'd also recommend making the string array explicit in your schema:
person = {
name : String,
favouriteFoods : [String]
}
The relevant documentation can be found here: https://docs.mongodb.com/manual/tutorial/query-arrays/

There is no $contains operator in mongodb.
You can use the answer from JohnnyHK as that works. The closest analogy to contains that mongo has is $in, using this your query would look like:
PersonModel.find({ favouriteFoods: { "$in" : ["sushi"]} }, ...);

I feel like $all would be more appropriate in this situation. If you are looking for person that is into sushi you do :
PersonModel.find({ favoriteFood : { $all : ["sushi"] }, ...})
As you might want to filter more your search, like so :
PersonModel.find({ favoriteFood : { $all : ["sushi", "bananas"] }, ...})
$in is like OR and $all like AND. Check this : https://docs.mongodb.com/manual/reference/operator/query/all/

In case that the array contains objects for example if favouriteFoods is an array of objects of the following:
{
name: 'Sushi',
type: 'Japanese'
}
you can use the following query:
PersonModel.find({"favouriteFoods.name": "Sushi"});

In case you need to find documents which contain NULL elements inside an array of sub-documents, I've found this query which works pretty well:
db.collection.find({"keyWithArray":{$elemMatch:{"$in":[null], "$exists":true}}})
This query is taken from this post: MongoDb query array with null values
It was a great find and it works much better than my own initial and wrong version (which turned out to work fine only for arrays with one element):
.find({
'MyArrayOfSubDocuments': { $not: { $size: 0 } },
'MyArrayOfSubDocuments._id': { $exists: false }
})

Incase of lookup_food_array is array.
match_stage["favoriteFoods"] = {'$elemMatch': {'$in': lookup_food_array}}
Incase of lookup_food_array is string.
match_stage["favoriteFoods"] = {'$elemMatch': lookup_food_string}

Though agree with find() is most effective in your usecase. Still there is $match of aggregation framework, to ease the query of a big number of entries and generate a low number of results that hold value to you especially for grouping and creating new files.
PersonModel.aggregate([
{
"$match": {
$and : [{ 'favouriteFoods' : { $exists: true, $in: [ 'sushi']}}, ........ ] }
},
{ $project : {"_id": 0, "name" : 1} }
]);

There are some ways to achieve this. First one is by $elemMatch operator:
const docs = await Documents.find({category: { $elemMatch: {$eq: 'yourCategory'} }});
// you may need to convert 'yourCategory' to ObjectId
Second one is by $in or $all operators:
const docs = await Documents.find({category: { $in: [yourCategory] }});
or
const docs = await Documents.find({category: { $all: [yourCategory] }});
// you can give more categories with these two approaches
//and again you may need to convert yourCategory to ObjectId
$in is like OR and $all like AND. For further details check this link : https://docs.mongodb.com/manual/reference/operator/query/all/
Third one is by aggregate() function:
const docs = await Documents.aggregate([
{ $unwind: '$category' },
{ $match: { 'category': mongoose.Types.ObjectId(yourCategory) } }
]};
with aggregate() you get only one category id in your category array.
I get this code snippets from my projects where I had to find docs with specific category/categories, so you can easily customize it according to your needs.

For Loopback3 all the examples given did not work for me, or as fast as using REST API anyway. But it helped me to figure out the exact answer I needed.
{"where":{"arrayAttribute":{ "all" :[String]}}}

In case You are searching in an Array of objects, you can use $elemMatch. For example:
PersonModel.find({ favoriteFoods : { $elemMatch: { name: "sushiOrAnytthing" }}});

With populate & $in this code will be useful.
ServiceCategory.find().populate({
path: "services",
match: { zipCodes: {$in: "10400"}},
populate: [
{
path: "offers",
},
],
});

If you'd want to use something like a "contains" operator through javascript, you can always use a Regular expression for that...
eg.
Say you want to retrieve a customer having "Bartolomew" as name
async function getBartolomew() {
const custStartWith_Bart = await Customers.find({name: /^Bart/ }); // Starts with Bart
const custEndWith_lomew = await Customers.find({name: /lomew$/ }); // Ends with lomew
const custContains_rtol = await Customers.find({name: /.*rtol.*/ }); // Contains rtol
console.log(custStartWith_Bart);
console.log(custEndWith_lomew);
console.log(custContains_rtol);
}

I know this topic is old, but for future people who could wonder the same question, another incredibly inefficient solution could be to do:
PersonModel.find({$where : 'this.favouriteFoods.indexOf("sushi") != -1'});
This avoids all optimisations by MongoDB so do not use in production code.

In mongoose, how to find records based on value in related collection?

In Mongoose, I have two collections, with one referencing the other. Is it possible to have a find query that selects records based on a value in the other. An example of what I am try to get at (not actual schemas):
const CarModelSchema = new mongoose.Schema({
name: String,
brand: { type: mongoose.Schema.Types.ObjectId, ref: 'CarBrand' }
});
const CarBrandSchema = new mongoose.Schema({
name: String,
country: String
});
I then want to perform a query of the form, without needing to do two queries:
CarModelSchema.find({ 'brand.country': 'GER' });
So far I haven't been able to make this work, so I am wondering whether this can be done in Mongo or whether I am approaching it wrong?

Yes it is possible.
I realize you don't have models for your schemas so add them like this:
const CarModel = mongoose.model('CarModel', CarModelSchema);
const CarBrand = mongoose.model('CarBrand', CarBrandSchema);
Also brands should be defined like this:
brand: [{ type: mongoose.Schema.Types.ObjectId, ref: 'CarBrand' }] //added the brackets
You can then run a find query to filter by country by doing the following:
CarModel.
find(...).
populate({
path: 'brand',
match: { country: { $eq: 'GER' }},
// You can even select the field you want using select like below,
select: 'name -_id',
//Even limit the amount of documents returned in the array
options: { limit: 5 }
}).
exec();
And that should do it, as long as the ObjectIds saved in brands array in the CarModel collection are valid or exist.

Using match in your population will do the work.
CarModel.find()
.populate({
path: 'brand',
model: CarBrandModel,
match: { country: { $eq: 'GER' }},
})
.exec()
Keep in mind you have to define CarModel and CarBrandModel like this:
const CarModel = mongoose.model('CarModel', CarModelSchema)
const CarBrandModel = mongoose.model('CarBrandModel', CarBrandSchema)

Yes, you are doing it wrong.
In CarModelSchema.brand there is not string saved, there is ObjectId saved, therefore you have to find that ObjectId (the reference).
You can do it manually - first finding the CarBrandSchema.find({ 'country': 'GER' }); and then use its ObjectId (=_id), or you can use https://mongoosejs.com/docs/populate.html to populate your CarModel with the CarBrand object.

Optimization - find on all fields in Mongoose MongoDB schema

We needed to challenge our database approach and need your help
We needed to search a word/phrase in all fields of a Mongoose schema.
Let's say the schema is like this:
var sampleSchema = new Schema({
fieldABC: String,
fieldDEF: String,
fieldGHI: String
});
We need to write a find query which will search for a word in all fields in a document of the collection:
db.sampleCollection.find({
$or: [{
fieldABC: "wordToSearch"
}, {
fieldDEF: "wordToSearch"
}, {
fieldGHI: "wordToSearch"
}]
})
It's possible for us to write the above query but it looks very inefficient - is there some better and faster approach to this?
In the year 2015, it was not supported, is there any change in this?

As suggested by #Veeram
Step 1:
Create a text index
db.sampleCollection.createIndex( { "$**": "text" } )
Step 2:
Use the text index to search the word in concern
db.sampleCollection.find( { $text: { $search: "wordToSearch" } })

Upsert data with a dynamic field name

I just try to do something simple with Mongo but it doesn't work:
I want to upsert datas in an object like: module.xxx.yyy then I tried many things like :
UsersRights.upsert({
condoId: condoId,
userId: manager._id,
}, {
condoId: condoId,
userId: manager._id,
module: {
[defaultRight.xxx] : {
[defaultRight.yyy] : defaultRight.default
}
}
});
but when I want to add a new xxx or a new yyy, it will erase and replace the entire module object and not only add a new key.
I also tried this :
UsersRights.upsert({
condoId: condoId,
userId: manager._id,
}, {
condoId: condoId,
userId: manager._id,
["module." + defaultRight.module + "." + defaultRight.right] : defaultRight.default,
});
but the server show me an error like: MinimongoError: Key module.xxx.yyy must not contain '.'

You need to use the following form:
YourCollection.upsert({
_id: id, (can be other selectors as well)
}, {
$set: setter
});
Setter is an object you create before and should have the following form:
const setter = {};
setter[`${#1Level}.${#2Level}`] = data;
Where #1Level & #2Level are vars naming the fields you want to modify or to add.

Cannot change _id field in Mongo DB from int to objectId using foreach [duplicate]

I want update an _id field of one document. I know it's not really good practice. But for some technical reason, I need to update it.
If I try to update it I get:
db.clients.update({ _id: ObjectId("123")}, { $set: { _id: ObjectId("456")}})
Performing an update on the path '_id' would modify the immutable field '_id'
And the update is rejected. How I can update it?

You cannot update it. You'll have to save the document using a new _id, and then remove the old document.
// store the document in a variable
doc = db.clients.findOne({_id: ObjectId("4cc45467c55f4d2d2a000002")})
// set a new _id on the document
doc._id = ObjectId("4c8a331bda76c559ef000004")
// insert the document, using the new _id
db.clients.insert(doc)
// remove the document with the old _id
db.clients.remove({_id: ObjectId("4cc45467c55f4d2d2a000002")})

To do it for your whole collection you can also use a loop (based on Niels example):
db.status.find().forEach(function(doc){
doc._id=doc.UserId; db.status_new.insert(doc);
});
db.status_new.renameCollection("status", true);
In this case UserId was the new ID I wanted to use

In case, you want to rename _id in same collection (for instance, if you want to prefix some _ids):
db.someCollection.find().snapshot().forEach(function(doc) {
if (doc._id.indexOf("2019:") != 0) {
print("Processing: " + doc._id);
var oldDocId = doc._id;
doc._id = "2019:" + doc._id;
db.someCollection.insert(doc);
db.someCollection.remove({_id: oldDocId});
}
});
if (doc._id.indexOf("2019:") != 0) {... needed to prevent infinite loop, since forEach picks the inserted docs, even throught .snapshot() method used.

Here I have a solution that avoid multiple requests, for loops and old document removal.
You can easily create a new idea manually using something like:_id:ObjectId()
But knowing Mongo will automatically assign an _id if missing, you can use aggregate to create a $project containing all the fields of your document, but omit the field _id. You can then save it with $out
So if your document is:
{
"_id":ObjectId("5b5ed345cfbce6787588e480"),
"title": "foo",
"description": "bar"
}
Then your query will be:
db.getCollection('myCollection').aggregate([
{$match:
{_id: ObjectId("5b5ed345cfbce6787588e480")}
}
{$project:
{
title: '$title',
description: '$description'
}
},
{$out: 'myCollection'}
])

You can also create a new document from MongoDB compass or using command and set the specific _id value that you want.

As a very small improvement to the above answers i would suggest using
let doc1 = {... doc};
then
db.dyn_user_metricFormulaDefinitions.deleteOne({_id: doc._id});
This way we don't need to create extra variable to hold old _id.

Slightly modified example of #Florent Arlandis above where we insert _id from a different field in a document:
> db.coll.insertOne({ "_id": 1, "item": { "product": { "id": 11 } }, "source": "Good Store" })
{ "acknowledged" : true, "insertedId" : 1 }
> db.coll.aggregate( [ { $set: { _id : "$item.product.id" }}, { $out: "coll" } ]) // inserting _id you want for the current collection
> db.coll.find() // check that _id is changed
{ "_id" : 11, "item" : { "product" : { "id" : 11 } }, "source" : "Good Store" }
Do not use $match filter + $out as in #Florent Arlandis's answer since $out fully remove data in collection before inserting aggregate result, so effectively you will loose all data that don't match to $match filter