I'd like to run a query on a Model, but only return embedded documents where the query matches. Consider the following...
var EventSchema = new mongoose.Schema({
typ : { type: String },
meta : { type: String }
});
var DaySchema = new mongoose.Schema({
uid: mongoose.Schema.ObjectId,
events: [EventSchema],
dateR: { type: Date, 'default': Date.now }
});
function getem() {
DayModel.find({events.typ : 'magic'}, function(err, days) {
// magic. ideally this would return a list of events rather then days
});
}
That find operation will return a list of DayModel documents. But what I'd really like is a list of EventSchemas alone. Is this possible?
It's not possible to fetch the Event objects directly, but you can restrict which fields your query returns like this:
DayModel.find({events.typ : 'magic'}, ['events'], function(err, days) {
...
});
You will still need to loop through the results to extract the actual embedded fields from the documents returned by the query, however.
Related
i have a product schema in my project, users can rate the products..the way i set the schema up is to store the number and sum of user ratings, then have a rating field where i would calculate the average of ratings so i can sort by it, but i can't find a way to automatically update this field whenever the product is updated.
the closest solution i had is to have the rating field's default value be a function that calculates the rating, but again it doesn't run automatically after the product's update
my schema looks like this
const productSchema = new Schema({
title: {
type: String,
required: true
},
views: {
type: Number,
default: 0
},
sumOfRatings: {
type: Number,
default: 0
},
numOfRatings: {
type: Number,
default: 0
},
rating: {
type: Number,
default: function() {
return this.sumOfRatings / this.numOfRatings
}
}, { collection: "Products", timestamps: true });
the question here describes something similar to what i want but there is no answer that does what i need
You can define a middleware for the findAndUpdateOne function, like this:
schema.pre('findOneAndUpdate', async function() {
const docToUpdate = await this.model.findOne(this.getQuery());
});
In this, you will first fetch the document and then set the updated value of the ratings.
i had to do something like this in the end..find the place, get sum and num of ratings from it and then calculate rating and do another query to update it with it, then call the updating function whenever needed..not a big fan of this solution but that's what i could come up with
function updateProductRating(id) {
Product.findById(id).then(product=> {
let calcRating = product.sumOfRatings / product.numOfRatings;
Product.findByIdAndUpdate(id, { rating: calcRating }).then(result=>{
console.log("###### update rating ######")
console.log(result)
})
})
}
I actually searched a ton and I saw a ton of mentions of my problem here but none of the things I tried helped me fix the issue i'm having.
I have a Room Scheme that looks like this:
const ObjectId = mongoose.Schema.ObjectId;
const roomSchema = mongoose.Schema({
users: [{
type: ObjectId,
ref: 'User'
}],
messages: [{
type: ObjectId,
ref: 'Message',
}],
post: {
type: ObjectId,
ref: 'Post'
}
});
As you can see I have an array of users with ref to another schema Users
I'm trying to query all the Rooms that has a User ObjectId in it (search ObjectId in an array).
while I can easily get this with querying mongo from cmd using this:
db.users.find({users:ObjectId('THE_OBJECT_ID')});
when I try to get the same while using mongoose it fails with:
Error: Argument passed in must be a single String of 12 bytes or a string of 24 hex characters
Here is how my route and find looks like:
app.route('/rooms/list/:user_id')
.get((req, res) => {
var query = { users: "USER_ID" };
Room.find(query ).populate('messages').then((data) => {
res.status(200).json(data);
}).catch((err) => {
console.log(err);
});
})
I tried to create type of object ID and use it but it still doesn't work.
var mongoose = require('mongoose'),
userId = 'THE_USER_ID';
var id = mongoose.Types.ObjectId(userId);
and than
Rooms.find({'users': id });
but it still doesn't work.
I also tried altering my query search using $in, $elemmatch it worked on cmd but failed when querying using mongoose.
Any help would be appreciated.
Issue :
If you check this :
var query = { users: "USER_ID" };
(Or)
userId = 'THE_USER_ID';
var id = mongoose.Types.ObjectId(userId);
What are you trying to do here ? You are passing in string USER_ID or THE_USER_ID as input and trying to convert it to type of ObjectId(). But string inside ObjectId() has certain restrictions which is why mongoose is failing to convert passed in string value to ObjectId() and getting error'd out.
Try this code :
Code :
const mongoose = require('mongoose');
app.route('/rooms/list/:user_id')
.get((req, res) => {
var query = { users: mongoose.Types.ObjectId(req.params.user_id) };
Room.find(query).populate('messages').then((data) => {
res.status(200).json(data);
}).catch((err) => {
console.log(err);
});
})
Your input should be value of user_id (Which will be string) - Convert it to ObjectId() and then query DB. So value of user_id should be a string that obeys ObjectId()'s restrictions, You can take string from one of existing doc's ObjectId() & test your get api.
I have learned that it is not possible to sort by populated field in mongodb during querying. Suppose I have a schema like below, and I have 1 million data in record. And i only need to return 10 records for each query, depending of the column sorting (asc/desc) and page defined. What are the effective solution to this problem?
Simplify problem:
In the front end, I will have a data table with column firstname, lastname, test.columnA and test.columnB. Each of this column is sortable by user.
My initial solution was to query everything out in mongoose, flattening it to json and using javascript to reorder and finally response the final 10 data only. But this will have bad performance impact with increasing data set.
var testSchema = {
columnA: { type: String },
columnB: { type: String },
}
var UserSchema = {
firstname: { type: string },
lastname: { type: string },
test: {
type: ObjectId,
ref: 'Test'
}
}
I'm using MongoDB as a log keeper for my app to then sync mobile clients. I have this models set up in NodeJS:
var UserArticle = new Schema({
date: { type: Number, default: Math.round((new Date()).getTime() / 1000) }, //Timestamp!
user: [{type: Schema.ObjectId, ref: "User"}],
article: [{type: Schema.ObjectId, ref: "Article"}],
place: Number,
read: Number,
starred: Number,
source: String
});
mongoose.model("UserArticle",UserArticle);
var Log = new Schema({
user: [{type: Schema.ObjectId, ref: "User"}],
action: Number, // O => Insert, 1 => Update, 2 => Delete
uarticle: [{type: Schema.ObjectId, ref: "UserArticle"}],
timestamp: { type: Number, default: Math.round((new Date()).getTime() / 1000) }
});
mongoose.model("Log",Log);
When I want to retrive the log I use the follwing code:
var log = mongoose.model('Log');
log
.where("user", req.session.user)
.desc("timestamp")
.populate("uarticle")
.populate("uarticle.article")
.run(function (err, articles) {
if (err) {
console.log(err);
res.send(500);
return;
}
res.json(articles);
As you can see, I want mongoose to populate the "uarticle" field from the Log collection and, then, I want to populate the "article" field of the UserArticle ("uarticle").
But, using this code, Mongoose only populates "uarticle" using the UserArticle Model, but not the article field inside of uarticle.
Is it possible to accomplish it using Mongoose and populate() or I should do something else?
Thank you,
From what I've checked in the documentation and from what I hear from you, this cannot be achieved, but you can populate the "uarticle.article" documents yourself in the callback function.
However I want to point out another aspect which I consider more important. You have documents in collection A which reference collection B, and in collection B's documents you have another reference to documents in collection C.
You are either doing this wrong (I'm referring to the database structure), or you should be using a relational database such as MySQL here. MongoDB's power relies in the fact you can embed more information in documents, thus having to make lesser queries (having your data in a single collection). While referencing something is ok, having a reference and then another reference doesn't seem like you're taking the full advantage of MongoDB here.
Perhaps you would like to share your situation and the database structure so we could help you out more.
You can use the mongoose-deep-populate plugin to do this. Usage:
User.find({}, function (err, users) {
User.deepPopulate(users, 'uarticle.article', function (err, users) {
// now each user document includes uarticle and each uarticle includes article
})
})
Disclaimer: I'm the author of the plugin.
I faced the same problem,but after hours of efforts i find the solution.It can be without using any external plugin:)
applicantListToExport: function (query, callback) {
this
.find(query).select({'advtId': 0})
.populate({
path: 'influId',
model: 'influencer',
select: { '_id': 1,'user':1},
populate: {
path: 'userid',
model: 'User'
}
})
.populate('campaignId',{'campaignTitle':1})
.exec(callback);
}
Mongoose v5.5.5 seems to allow populate on a populated document.
You can even provide an array of multiple fields to populate on the populated document
var batch = await mstsBatchModel.findOne({_id: req.body.batchId})
.populate({path: 'loggedInUser', select: 'fname lname', model: 'userModel'})
.populate({path: 'invoiceIdArray', model: 'invoiceModel',
populate: [
{path: 'updatedBy', select: 'fname lname', model: 'userModel'},
{path: 'createdBy', select: 'fname lname', model: 'userModel'},
{path: 'aircraftId', select: 'tailNum', model: 'aircraftModel'}
]});
how about something like:
populate_deep = function(type, instance, complete, seen)
{
if (!seen)
seen = {};
if (seen[instance._id])
{
complete();
return;
}
seen[instance._id] = true;
// use meta util to get all "references" from the schema
var refs = meta.get_references(meta.schema(type));
if (!refs)
{
complete();
return;
}
var opts = [];
for (var i=0; i<refs.length; i++)
opts.push({path: refs[i].name, model: refs[i].ref});
mongoose.model(type).populate(instance, opts, function(err,o){
utils.forEach(refs, function (ref, next) {
if (ref.is_array)
utils.forEach(o[ref.name], function (v, lnext) {
populate_deep(ref.ref_type, v, lnext, seen);
}, next);
else
populate_deep(ref.ref_type, o[ref.name], next, seen);
}, complete);
});
}
meta utils is rough... want the src?
or you can simply pass an obj to the populate as:
const myFilterObj = {};
const populateObj = {
path: "parentFileds",
populate: {
path: "childFileds",
select: "childFiledsToSelect"
},
select: "parentFiledsToSelect"
};
Model.find(myFilterObj)
.populate(populateObj).exec((err, data) => console.log(data) );
I am using Mongoose to model Person and Transaction collections, where each Transaction will have references to two different Person instances:
var TransactionSchema = new Schema({
, amount : { type: Number, required: true }
, from : { type: ObjectId, required: true }
, to : { type: ObjectId, required: true }
, date : Date
});
var PersonSchema = new Schema({
name : { type: String, required: true }
, transactions : [ObjectId]
});
I'd like each Person to have a collection of all the Transactions that they are either the to or from value for. So far, this is the best way I've been able to figure out how to do it:
TransactionSchema.pre('save', function(next, done) {
var transaction = this;
Person.findById(this.to, function (err, person) {
person.transactions.push(transaction);
person.save();
});
Person.findById(this.from, function (err, person) {
person.transactions.push(transaction);
person.save();
});
next();
});
This seems excessive. Is there a better way to do it, or am I trying to use MongoDB too much like a relational database? Instead of having a collection of Transactions associated with each Person instance, should I just be querying the Translation collection directly?
Thank you.
You've got to think more on the queries you are going to execute on the database when you design the MongoDB schema.
Try to duplicate data for speed and reference it for integrity. What does that mean?
Well, for example when you make a query for a Transaction, I guess you don't need all the user details from the first time no? (do you need the user's email, location when displaying info on a Transaction?)
I think you just probably need the user id and the username, so you should do something like this:
var TransactionSchema = new Schema({
, amount : { type: Number, required: true }
, from : {
user_id: {
type: ObjectId
, required: true
}
, username: {
type: String
, required: true
}
}
, to : {
user_id: {
type: ObjectId
, required: true
}
, username: {
type: String
, required: true
}
}
, date : Date
});
So instead of doing 3 queries for the page displaying the Transaction details (one for the transaction and 2 additional queries for the usernames), you'll have just one.
This is just an example, you could apply the same logic for the User schema, depending on what you're trying to achieve.
Anyway I don't think your middleware is ok, since you are not checking for errors there (you are always calling next no matter what). This is how I would write the middleware (didn't test, but the idea is important):
TransactionSchema.pre('save', function(next, done) {
var transaction = this;
Person.where('_id').in([this.to, this.from]).run(function (err, people) {
if (people.length != 2) { next(new Error("To or from doesn't exist")); return; }
Step(
function save_to() {
people[0].transactions.push(transaction);
people[0].save(this);
},
function save_from(err) {
if (err) { next(err); return; }
people[1].transactions.push(transaction);
people[1].save(this);
},
function callback(err) {
next(err);
}
);
});
});
In the code above I'm using the Step library for flow control and I'm only using one query instead of two (when searching for "to" and "from").