Im coding an app in Node.js which is using MongoDB. I chose MongooseJS to handle my DB queries.
I have two collections that are referenced to each other (Room which is the 'superior' collection and DeviceGroups which is contained within Room collection).
I have a query that gets a list of all of the rooms from Room collection, populates deviceGroups field (which is the Rooms reference to DeviceGroup collection) and inside it there is a map method that goes through every room found in the Room collection and for every room it makes another query - it looks for any deviceGroups in DeviceGroup collection that are referenced to the current room in the map method.
My goal here is to return a list of all of the rooms with deviceGroups field filled in with actual data, not only references.
What I am getting after the queries (inside the then method) is a Mongoose document. The whole algorithm is used as a handler of a GET method, so I need a pure JavaScript object as a response.
Main goal I want to achieve is to get result of all of the queries and population inside them as pure javascript object, so I can create a response object and send it (i dont want to send everything that db returns, because not all of the data is needed for this case)
EDIT:
I am so sorry, I have deleted my code and didnt realize it.
My current code is below:
Schema:
const roomSchema = Schema({
name: {
type: String,
required: [true, 'Room name not provided']
},
deviceGroups: [{
type: Schema.Types.ObjectId,
ref: 'DeviceGroup'
}]
}, { collection: 'rooms' });
const deviceGroupSchema = Schema({
parentRoomId: {
type: Schema.Types.ObjectId,
ref: 'Room'
},
groupType: {
type: String,
enum: ['LIGHTS', 'BLINDS', 'ALARM_SENSORS', 'WEATHER_SENSORS']
},
devices: [
{
type: Schema.Types.ObjectId,
ref: 'LightBulb'
}
]
}, { collection: 'deviceGroups' });
Queries:
app.get('/api/id/rooms', function(req, res) {
Room.find({}).populate('deviceGroups').lean().exec(function(err, parentRoom) {
parentRoom.map(function(currentRoom) {
DeviceGroup.findOne({ parentRoomId: currentRoom._id }, function (err, devices) {
return devices;
});
});
}).then(function(roomList) {
res.send(roomList);
});
});
where are you confusing. here is a simple and effective code snippet
Room.findById(req.params.id)
.select("roomname")
.populate({
path: 'deviceGroup',
select: 'devicename',
model:'DeviceGroups'
populate:{
path: 'device',
select: 'devicename',
model:'Device'
}
})
.lean()
.exec((err, data)=>{
console.log(data);
})
Related
I am building an education application and I am trying to add/update a field which is an array of objects with addToSet from a javascript array, and if the object already exists (matched with objectId) I want to update the already existing object's array (addToSet) and change another field of that same object.
My model looks like this (simplified):
const course = new Schema(
{
events: [
{
type: Schema.Types.ObjectId,
ref: 'event'
}
],
students: [
{
user: {
type: Schema.Types.ObjectId,
ref: 'user'
},
status: {
type: String,
enum: ['notBooked', 'booked', 'attended', 'completed']
},
events: [
{
type: Schema.Types.ObjectId,
ref: 'event'
}
]
}
],
});
And ideally I would like to use an updateOne query to both addToSet to the course's list of events, while also updating the students list.
Currently I am using this code to accomplish my updates by first finding the course and then using javascript to update it, which works:
const studentsToAdd = this.attendees.map((attendee) => ({
user: attendee._id,
status: 'booked',
events: [this._id]
}));
const studentIds = studentsToAdd.map((student) => student.user);
const course = await courseModel.findById(this.course);
console.log(studentIds);
course.events.push(this._id);
course.students.forEach((student) => {
if (studentIds.some((s) => s.equals(student.user))) {
student.events.push(this._id);
student.status = 'booked';
studentsToAdd.splice(studentsToAdd.indexOf(studentsToAdd.find((s) => s.user.equals(student.user))), 1);
}
});
course.students.push(...studentsToAdd);
course.save();
However I am curious if it is possible to solve this using a single updateOne on the courseModel schema.
This is part of a mongoose middleware function, and "this" references an event object, which has its own _id, attendees of the event, and the course ID (named course).
The goal is to add the student object part of studentsToAdd to the students array of the course IF the student does not exist (signified by user being a reference by objectId), and if the student already exists then I want to add the eventId (this._id) to the events array for that particular student and set status for that student to "booked".
Is this possible? I have tried many iterations using $cond, $elemmatch, "students.$[]" and so forth but I am quite new to mongodb and am unsure how to go about this.
I have these two 3 models User, Product and Orders and are also has references to each other.
My Orders Schema:
const orderSchema = Schema({
buyerId:{
type: Schema.Types.ObjectId,
ref: 'User'
},
totalAmount: {
type: Number,
required: [true, "description is required"]
},
createdOn: {
type: Date,
default: new Date()
},
items:[{type:Schema.Types.ObjectId, ref: 'Product'}]})
I'm trying to use populate() like this:
Order.find()
.populate('buyerId')//Reference to User Model
.populate('items')// Reference to Product Model
.exec(function (err, result){
console.log(result);// RETURNS ONLY buyerId populated
console.log(result.buyerId.name);//Successfully references to my User model and prints name
console.log(result.items);//Prints Undefined
})
You can see my console log above and what it returns is only the populated buyerId(only got the reference from my User model)
Seems like my populate('items') doesnt work at all. The items field contains array of IDs, where the IDs are those of products. I need to reference to User and Product both. I'm just following the documentation in mongoose, I don't know what I might be doing wrong.
use aggregate
Order.aggregate([
{ $match:{ user:"sample_id"
}
},
{$lookup:{
from:'users', // users collection name
localField:'buyerId',
foreignField:'_id',
as:'buyerId'
}},
{
$lookup:{
from:'items', //items collection name
localField:'items',
foreignField:'_id',
as:'items'
}
},
])
I have a very simple mongo scheme I'm accessing with mongoose
I can map the username and firstname to each notification's from field by using populate, the issue is I can't seem to get any sorting to work on the date field
With this code I get an error of
MongooseError: Cannot populate with sort on path notifications.from
because it is a subproperty of a document array
Is it possible to do this a different way, or newer way (deep populate, virtuals)? I'm on Mongoose 5.
I'd rather not use vanilla javascript to sort the object afterwards or create a separate schema
var UserSchema = new Schema({
username: String,
firstname: String,
notifications: [
{
from: { type: Schema.Types.ObjectId, ref: 'User'},
date: Date,
desc: String
}
]
});
app.get('/notifications', function(req, res) {
User.findOne({ _id: req._id }, 'notifications')
.populate({
path: 'notifications.from',
populate: {
path: 'from',
model: 'User',
options: { sort: { 'notifications.date': -1 } }
}
})
.exec(function(err, user) {
if (err) console.log(err)
})
});
That possible duplicate is almost 2 years old about Mongo. I'm asking if there are newer or different ways of doing this in Mongoose as it has changed a bit since 2016 with newer features.
From Mongoose V5.0.12 FAQ : http://mongoosejs.com/docs/faq.html#populate_sort_order
Q. I'm populating a nested property under an array like the below
code:
new Schema({
arr: [{
child: { ref: 'OtherModel', type: Schema.Types.ObjectId }
}] });
.populate({ path: 'arr.child', options: { sort: 'name' } }) won't sort by arr.child.name?
A. See this GitHub issue. It's a known issue but one that's
exceptionally difficult to fix.
So unfortunately, for now, it's not possible,
One way to achieve this is to simply use javascript's native sort to sort the notifications after fetching.
.exec(function(err, user) {
if (err) console.log(err)
user.notifications.sort(function(a, b){
return new Date(b.date) - new Date(a.date);
});
})
It can be achievable using nesting populate like this -
eg - schema - {donationHistory: {campaignRequestId: [ref ids]}}
await user.populate({
path: 'donationHistory.campaignRequestId',
populate: [{
path: 'campaignRequestId',
model: 'CampaignRequest',
options: { sort: { 'createdAt': -1 } },
}],
...deepUserPopulation,
}).execPopulate();
I have the following schemas for the document Folder:
var permissionSchema = new Schema({
role: { type: String },
create_folders: { type: Boolean },
create_contents: { type: Boolean }
});
var folderSchema = new Schema({
name: { type: string },
permissions: [ permissionSchema ]
});
So, for each Page I can have many permissions. In my CMS there's a panel where I list all the folders and their permissions. The admin can edit a single permission and save it.
I could easily save the whole Folder document with its permissions array, where only one permission was modified. But I don't want to save all the document (the real schema has much more fields) so I did this:
savePermission: function (folderId, permission, callback) {
Folder.findOne({ _id: folderId }, function (err, data) {
var perm = _.findWhere(data.permissions, { _id: permission._id });
_.extend(perm, permission);
data.markModified("permissions");
data.save(callback);
});
}
but the problem is that perm is always undefined! I tried to "statically" fetch the permission in this way:
var perm = data.permissions[0];
and it works great, so the problem is that Underscore library is not able to query the permissions array. So I guess that there's a better (and workgin) way to get the subdocument of a fetched document.
Any idea?
P.S.: I solved checking each item in the data.permission array using a "for" loop and checking data.permissions[i]._id == permission._id but I'd like a smarter solution, I know there's one!
So as you note, the default in mongoose is that when you "embed" data in an array like this you get an _id value for each array entry as part of it's own sub-document properties. You can actually use this value in order to determine the index of the item which you intend to update. The MongoDB way of doing this is the positional $ operator variable, which holds the "matched" position in the array:
Folder.findOneAndUpdate(
{ "_id": folderId, "permissions._id": permission._id },
{
"$set": {
"permissions.$": permission
}
},
function(err,doc) {
}
);
That .findOneAndUpdate() method will return the modified document or otherwise you can just use .update() as a method if you don't need the document returned. The main parts are "matching" the element of the array to update and "identifying" that match with the positional $ as mentioned earlier.
Then of course you are using the $set operator so that only the elements you specify are actually sent "over the wire" to the server. You can take this further with "dot notation" and just specify the elements you actually want to update. As in:
Folder.findOneAndUpdate(
{ "_id": folderId, "permissions._id": permission._id },
{
"$set": {
"permissions.$.role": permission.role
}
},
function(err,doc) {
}
);
So this is the flexibility that MongoDB provides, where you can be very "targeted" in how you actually update a document.
What this does do however is "bypass" any logic you might have built into your "mongoose" schema, such as "validation" or other "pre-save hooks". That is because the "optimal" way is a MongoDB "feature" and how it is designed. Mongoose itself tries to be a "convenience" wrapper over this logic. But if you are prepared to take some control yourself, then the updates can be made in the most optimal way.
So where possible to do so, keep your data "embedded" and don't use referenced models. It allows the atomic update of both "parent" and "child" items in simple updates where you don't need to worry about concurrency. Probably is one of the reasons you should have selected MongoDB in the first place.
In order to validate subdocuments when updating in Mongoose, you have to 'load' it as a Schema object, and then Mongoose will automatically trigger validation and hooks.
const userSchema = new mongoose.Schema({
// ...
addresses: [addressSchema],
});
If you have an array of subdocuments, you can fetch the desired one with the id() method provided by Mongoose. Then you can update its fields individually, or if you want to update multiple fields at once then use the set() method.
User.findById(userId)
.then((user) => {
const address = user.addresses.id(addressId); // returns a matching subdocument
address.set(req.body); // updates the address while keeping its schema
// address.zipCode = req.body.zipCode; // individual fields can be set directly
return user.save(); // saves document with subdocuments and triggers validation
})
.then((user) => {
res.send({ user });
})
.catch(e => res.status(400).send(e));
Note that you don't really need the userId to find the User document, you can get it by searching for the one that has an address subdocument that matches addressId as follows:
User.findOne({
'addresses._id': addressId,
})
// .then() ... the same as the example above
Remember that in MongoDB the subdocument is saved only when the parent document is saved.
Read more on the topic on the official documentation.
If you don't want separate collection, just embed the permissionSchema into the folderSchema.
var folderSchema = new Schema({
name: { type: string },
permissions: [ {
role: { type: String },
create_folders: { type: Boolean },
create_contents: { type: Boolean }
} ]
});
If you need separate collections, this is the best approach:
You could have a Permission model:
var mongoose = require('mongoose');
var PermissionSchema = new Schema({
role: { type: String },
create_folders: { type: Boolean },
create_contents: { type: Boolean }
});
module.exports = mongoose.model('Permission', PermissionSchema);
And a Folder model with a reference to the permission document.
You can reference another schema like this:
var mongoose = require('mongoose');
var FolderSchema = new Schema({
name: { type: string },
permissions: [ { type: mongoose.Schema.Types.ObjectId, ref: 'Permission' } ]
});
module.exports = mongoose.model('Folder', FolderSchema);
And then call Folder.findOne().populate('permissions') to ask mongoose to populate the field permissions.
Now, the following:
savePermission: function (folderId, permission, callback) {
Folder.findOne({ _id: folderId }).populate('permissions').exec(function (err, data) {
var perm = _.findWhere(data.permissions, { _id: permission._id });
_.extend(perm, permission);
data.markModified("permissions");
data.save(callback);
});
}
The perm field will not be undefined (if the permission._id is actually in the permissions array), since it's been populated by Mongoose.
just try
let doc = await Folder.findOneAndUpdate(
{ "_id": folderId, "permissions._id": permission._id },
{ "permissions.$": permission},
);
I have models called "Activities" that I am querying for (using Mongoose). Their schema looks like this:
var activitySchema = new mongoose.Schema({
actor: {
type: mongoose.Schema.ObjectId,
ref: 'User',
required: true
},
recipient: {
type: mongoose.Schema.ObjectId,
ref: 'User'
},
timestamp: {
type: Date,
default: Date.now
},
activity: {
type: String,
required: true
},
event: {
type: mongoose.Schema.ObjectId,
ref: 'Event'
},
comment: {
type: mongoose.Schema.ObjectId,
ref: 'Comment'
}
});
When I query for them, I am populating the actor, recipient, event, and comment fields (all the references). After that, I also deep-populate the event field to get event.creator. Here is my code for the query:
var activityPopulateObj = [
{ path: 'event' },
{ path: 'event.creator' },
{ path: 'comment' },
{ path: 'actor' },
{ path: 'recipient' },
{ path: 'event.creator' }
],
eventPopulateObj = {
path: 'event.creator',
model: User
};
Activity.find({ $or: [{recipient: user._id}, {actor: {$in: user.subscriptions}}, {event: {$in: user.attending}}], actor: { $ne: user._id} })
.sort({ _id: -1 })
.populate(activityPopulateObj)
.exec(function(err, retrievedActivities) {
if(err || !retrievedActivities) {
deferred.reject(new Error("No events found."));
}
else {
User.populate(retrievedActivities, eventPopulateObj, function(err, data){
if(err) {
deferred.reject(err.message);
}
else {
deferred.resolve(retrievedActivities);
}
});
}
});
This is already a relatively complex query, but I need to do even more. If it hits the part of the $or statement that says {actor: {$in: user.subscriptions}}, I also need to make sure that the event's privacy field is equal to the string public. I tried using $elemMatch, but since the event has to be populated first, I couldn't query any of its fields. I need to achieve this same goal in multiple other queries, as well.
Is there any way for me to achieve this further filtering like I have described?
The answer is to change your schema.
You've fallen into the trap that many devs have before you when coming into document database development from a history of using relational databases: MongoDB is not a relational database and should not be treated like one.
You need to stop thinking about foreign keys and perfectly normalized data and instead, keep each document as self-contained as possible, thinking about how to best embed relevant associated data within your documents.
This doesn't mean you can't maintain associations as well. It might mean a structure like this, where you embed only necessary details, and query for the full record when needed:
var activitySchema = new mongoose.Schema({
event: {
_id: { type: ObjectId, ref: "Event" },
name: String,
private: String
},
// ... other fields
});
Rethinking your embed strategy will greatly simplify your queries and keep the query count to a minimum. populate will blow your count up quickly, and as your dataset grows this will very likely become a problem.
You can try below aggregation. Look at this answer: https://stackoverflow.com/a/49329687/12729769
And then, you can use fields from $addFields in your query. Like
{score: {$gte: 5}}
but since the event has to be populated first, I couldn't query any of its fields.
No can do. Mongodb cannot do joins. When you make a query, you can work with exactly one collection at a time. And FYI all those mongoose populates are additional, distinct database queries to load those records.
I don't have time to dive into the details of your schema and application, but most likely you will need to denormalize your data and store a copy of whatever event fields you need to join on in the primary collection.