Develop Reference

How can I add to this schema array with mongoose?

Here's the user schema and the part I want to update is ToDo under User.js (further down). I am attempting to add new data to an array within the db.
data.js
app.post("/data", loggedIn, async (req, res) => {
console.log(req.body.content);
let content = { content: req.body.content };
User.update({ _id: req.user._id }, { $set: req.body }, function (err, user) {
if (err) console.log(err);
if (!content) {
req.flash("error", "One or more fields are empty");
return res.redirect("/");
}
user.ToDo.push(content);
res.redirect("/main");
});
});
User.js
new mongoose.Schema({
email: String,
passwordHash: String,
ToDo: {
type: [],
},
date: {
type: Date,
default: Date.now,
},
})
Originally I was trying the .push() attribute, but I get the error:
user.ToDo.push(content);
^
TypeError: Cannot read property 'push' of undefined

First of all, your problem is the callback is not the user. When you use update the callback is something like this:
{ n: 1, nModified: 1, ok: 1 }
This is why the error is thrown.
Also I recommend specify the array value, something like this:
ToDo: {
type: [String],
}
The second recommendation is to do all you can into mongo query. If you can use a query to push the object, do this instead of store the object into memory, push using JS function and save again the object into DB.
Of course you can do that, but I think is worse.
Now, knowing this, if you only want to add a value into an array, try this query:
var update = await model.updateOne({
"email": "email"
},
{
"$push": {
"ToDo": "new value"
}
})
Check the example here
You are using $set to your object, so you are creating a new object with new values.
Check here how $set works.
If fields no exists, will be added, otherwise are updated. If you only want to add an element into an array from a specified field, you should $push into the field.
Following your code, maybe you wanted to do something similar to this:
model.findOne({ "email": "email" }, async function (err, user) {
//Here, user is the object user
user.ToDo.push("value")
user.save()
})
As I said before, that works, but is better do in a query.

Is there a way to remove sub-document from object without passing the parentId?

Is there a way to remove sub-document from object without passing the parentId?
So I have a document which looks like this:
name: {
type: [String],
trim: true,
required: [true, 'Please add your name']
},
experience: [
{
title: {
type: String,
trim: true,
required: [true, 'Please add an experience title']
}
}
],
Each of this document can have several objects in the experience array.
Adding and updating has been easy for me because I usually just need to pass the Id of the parent document.
Now I would like to delete any object of said experience array by proving only its id...not the parentId.
Hopefull this code can help explain what I'm looking for:
const resume = await Resume.findByIdAndUpdate(
{
// _id: req.params.id, // <=== is the parent id...
experience: { _id: req.params.exp_id }
},
{
$pull: { experience: { _id: req.params.exp_id } }
},
{
new: true,
runValidators: true
}
);
You can see in the code above that I passed the _id of the parent document which if I continue this way, it works great but for my needs I need to only pass the _id of the subdocument.
Is that actually possible?

Yes you can, using {} searches in all parent documents.
parent.updateMany({}, {$pull, {children: {_id: id}}})
Please also make sure the child _id is a string and not ObjectId. If that's the case you need to first convert your string to ObjectId

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.

How to exclude one particular field from a collection in Mongoose?

I have a NodeJS application with Mongoose ODM(Mongoose 3.3.1). I want to retrieve all fields except 1 from my collection.For Example: I have a collection Product Which have 6 fields,I want to select all except a field "Image" . I used "exclude" method, but got error..
This was my code.
var Query = models.Product.find();
Query.exclude('title Image');
if (req.params.id) {
Query.where('_id', req.params.id);
}
Query.exec(function (err, product) {
if (!err) {
return res.send({ 'statusCode': 200, 'statusText': 'OK', 'data': product });
} else {
return res.send(500);
}
});
But this returns error
Express
500 TypeError: Object #<Query> has no method 'exclude'.........
Also I tried, var Query = models.Product.find().exclude('title','Image'); and var Query = models.Product.find({}).exclude('title','Image'); But getting the same error. How to exclude one/(two) particular fields from a collection in Mongoose.

Use query.select for field selection in the current (3.x) Mongoose builds.
Prefix a field name you want to exclude with a -; so in your case:
Query.select('-Image');
Quick aside: in JavaScript, variables starting with a capital letter should be reserved for constructor functions. So consider renaming Query as query in your code.

I don't know where you read about that .exclude function, because I can't find it in any documentation.
But you can exclude fields by using the second parameter of the find method.
Here is an example from the official documentation:
db.inventory.find( { type: 'food' }, { type:0 } )
This operation returns all documents where the value of the type field is food, but does not include the type field in the output.

Model.findOne({ _id: Your Id}, { password: 0, name: 0 }, function(err, user){
// put your code
});
this code worked in my project. Thanks!! have a nice day.

You could do this
const products = await Product.find().select(['-image'])

I am use this with async await
async (req, res) => {
try {
await User.findById(req.user,'name email',(err, user) => {
if(err || !user){
return res.status(404)
} else {
return res.status(200).json({
user,
});
}
});
} catch (error) {
console.log(error);
}

In the updated version of Mongoose you can use it in this way as below to get selected fields.
user.findById({_id: req.body.id}, 'username phno address').then(response => {
res.status(200).json({
result: true,
details: response
});
}).catch(err => {
res.status(500).json({ result: false });
});

I'm working on a feature. I store a userId array name "collectedUser" than who is collected the project. And I just want to return a field "isCollected" instead of "collectedUsers". So select is not what I want. But I got this solution.
This is after I get projects from database, I add "isCollected".
for (const item of projects) {
item.set("isCollected", item.collectedUsers.includes(userId), {
strict: false,
})
}
And this is in Decorator #Schema
#Schema({
timestamps: true,
toObject: {
virtuals: true,
versionKey: false,
transform: (doc, ret, options): Partial<Project> => {
return {
...ret,
projectManagers: undefined,
projectMembers: undefined,
collectedUsers: undefined
}
}
}
})
Finally in my controller
projects = projects.map(i => i.toObject())
It's a strange tricks that set undefined, but it really work.
Btw I'm using nestjs.

You can do it like this
const products = await Product.find().select({
"image": 0
});

For anyone looking for a way to always omit a field - more like a global option rather than doing so in the query e.g. a password field, using a getter that returns undefined also works
{
password: {
type: String,
required: true,
get: () => undefined,
},
}
NB: Getters must be enabled with option { toObject: { getters:true } }

you can exclude the field from the schema definition
by adding the attribute
excludedField : {
...
select: false,
...
}
whenever you want to add it to your result,
add this to your find()
find().select('+excludedFiled')

Mongoose embedded document updating

I have a problem with embedded document update.
My defined Schemas:
var Talk = new Schema({
title: {
type: String,
required: true
},
content: {
type: String,
required: true
},
date: {
type: Date,
required: true
},
comments: {
type: [Comments],
required: false
},
vote: {
type: [VoteOptions],
required: false
},
});
var VoteOptions = new Schema({
option: {
type: String,
required: true
},
count: {
type: Number,
required: false
}
});
Now I would like to update vote.count++, with given Talk id and VoteOption id. I have the following function to do the job:
function makeVote(req, res) {
Talk.findOne(req.params.id, function(err, talk) {
for (var i = 0; i < talk.vote.length; i++) {
if (talk.vote[i]._id == req.body.vote) {
talk.vote[i].count++;
}
}
talk.save(function(err) {
if (err) {
req.flash('error', 'Error: ' + err);
res.send('false');
} else {
res.send('true');
}
});
});
}
Everything executes, I get back the res.send('true'), but the value on count does not change.
When I did some console.log I saw that it changed the value, but the talk.save just doesn't save it in db.
Also I'm quite unhappy about the cycle just to find _id of embedded doc. In the mongoose documentation I read about talk.vote.id(my_id) but that gives me error of not having an id function.

When updating a Mixed type (which seems to be anything else than a basic type, so that also includes embedded documents), one has to call .markModified on the document. In this case, it would be:
talk.markModified("vote"); // mention that `talk.vote` has been modified
talk.save(function(err) {
// ...
});
Hope this helps someone in the future since I couldn't find the answer very quickly.
Reference:
... Mongoose loses the ability to auto detect/save those changes. To "tell" Mongoose that the value of a Mixed type has changed, call the .markModified(path) method of the document passing the path to the Mixed type you just changed.

It's because you are trying to save your talk object before the callback which increments count has been fired. Also, did you make sure to instantiate your Talk schema? eg:
var talk = new Talk();
However, if all you want to do is increment your count variable, mongo supports atomic, in-place updates which you may find useful:
talk.find( { _id : req.body.vote }, { $inc: { count : 1 } } );
have a look at:
http://www.mongodb.org/display/DOCS/Updating#Updating-%24inc