Mongoose Proper Syntax to Find by Child ID - javascript

Using the model.find method I can find documents that match all properties defined within my schema except when a property has a type of mongoose.Schema.ObjectId. In my case, references to the owner of the document. I've tried all sorts of ways to get documents by the owner _id but nothing is working. Anybody know the proper way to do this ?
--EDIT--
Just in case anybody runs into the same issue, I got it working using the following query.
Query:
const users_cars = await Cars.find( { owner: user_id } );
Schema:
const Schema = new mongoose.Schema({
type: Object,
owner: {
type: mongoose.Schema.ObjectId,
ref: 'User',
required: [ true, 'car must belong to an owner' ]
},
name: String
});

Related

MongoDB/Mongoose: AddToSet an array into an array field, but also addToSet a nested array field value if the parent object already exists

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.

Adding documents to a Many to Many relationship in Mongoose (MongoDB)

I have a User collection and a Task Collection. Many Users can have many Tasks, and Many Tasks can have many Users. The proper way I believe in doing this is the following models:
var UserSchema = new Schema({
id: ObjectId,
username: { type: String, required: true },
assignments: [ {type : mongoose.Schema.ObjectId, ref : 'Assignment'} ]
});
var TaskSchema = new Schema({
id: ObjectId,
title: { type: String, default: '' },
information: { type: String, default: '' },
assignments: [ {type : mongoose.Schema.ObjectId, ref : 'Assignment'} ]
});
var AssignmentSchema = new Schema({
id: ObjectId,
isCompleted: { type: Boolean, default: false },
completionDate: { type: Date, default: null },
tasks: [ {type : mongoose.Schema.ObjectId, ref : 'Task'} ],
users: [ {type : mongoose.Schema.ObjectId, ref : 'User'} ]
});
If the above models are correct, how do you insert a Task with multiple user assignments? I understand that you would create the Task document first to get its ObjectId, but after that would you just insert all of the assignments into the Assignment collection (with their proper Task and User objectId's) and thats it? Or would I have to insert all of the assignments then edit each individual User and Task to insert the AssignmentId into their assignments property.
I am sure there is a stack over flow question like this already, but I have not been able to find one. Any help is appreciated!
I believe you have the answer in your question.
Create a new task, capture the task id. Then find or create a new user, edit or add the task’s id, capture the user id. Add the user id to the task. Repeat for additional users.
I believe this is what you say in the final part of your question?
I don’t see why this cannot work.

Enforcing the default value in Mongoose schema

I have been trying to find a way to enforce the default value of a schema so that the default value is being used upon insert regardless of any input parameter. In other words a property of a schema should always have the default value and if any other parameter is being passed on insert/write that passed parameter would be ignored.
As an example, please see my dummy schema below. The property I want to enforce is MySchema.created, which is supposed to store the timestamp of the moment document gets created.
var mongoose = require("mongoose");
var MySchema = new mongoose.Schema({
sendStatus: {
type: String,
enum: ["notsent", "sent", "failed"],
default: "notsent"
},
created: {
type: Date,
default: Date.now
},
creator: {
type: mongoose.Schema.Types.ObjectId,
ref: "User",
required: true
}
});
I did not find an answer in Mongoose documentation (http://mongoosejs.com/docs/defaults.html) even though it do mention setDefaultsOnInsert, which sounds somewhat close. Altough I would like to do all the schema validation and enforcements on schema level to avoid development mistakes and copy-paste code. Also I don't see how I could use setDefaultsOnInsert for this timestamp, because I want to keep it also constant and not update it upon document update.
Is this possible to achieve? Having a reliable creation date on a document must be a very common use case, but somehow I fail to find a satisfying answer in the internet. Thanks!
You can simply add Mongoose timestamps to the end of your schema and it will timestamp your new/updated document
var MySchema = new mongoose.Schema({
sendStatus: {
type: String,
enum: ["notsent", "sent", "failed"],
default: "notsent"
},
creator: {
type: mongoose.Schema.Types.ObjectId,
ref: "User",
required: true
}
},{
timestamps:
{
createdAt: 'created_at',
updatedAt: 'updated_at' //leave this out if of no interest
}
});

Cast to ObjectId failed for value error in Mongoose findOne

I've been struggling with a weird exception and still confused about it after an hour.
CastError: Cast to ObjectId failed for value "pedrammarandi#gmail.com"
at path "_id" for model "Account"
I'm trying to retrieve an Account via email address. Here is my query
export async function getPendingRecipients(user_id, email_address) {
const account = await Account
.find({email: email_address})
.exec();
return true;
}
This is my Schema object
const userGmailSchema = new Schema({
id: {
type: String,
unique: true
},
displayName: String,
image: Object,
accessToken: String,
user: {
type: Schema.Types.ObjectId,
ref: 'User'
},
refreshToken: {
type: String,
default: null
},
email: {
type: String,
unique: true
},
emails: [
{
type: Schema.Types.ObjectId,
ref: 'Emails'
}
]
});
I'm not sure, but I guess the problem is you wrote an id field.
In MongoDB, the "primary key" is _id field, which is an ObjectId object (actually it's a 12-byte-value), and in mongoose, id is a virtual getter of _id, easily said, id is an alias of _id.
(A little different is that, _id returns ObjectId, id returns String version of _id.)
By default, mongoose manage _id field automatically, so commonly we should not write anything about id in schema.
If your id is for something like primary key ID in SQL DB, just remove it from mongoose schema. If it's means something else in your app, try to add an option:
const userGmailSchema = new Schema({
// your schemas here
},
{
{ id: false } // disable the virtual getter
})
or rename it.
http://mongoosejs.com/docs/guide.html#id
Hope this helps.

MongoDB query on populated fields

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.

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