Hey so I'm pretty new to Javascript and Node but I'm running into an issue that's been bothering me for a while.
I have a User model and an Image model, I'm using Multer to upload an array of images and trying to loop through this array, create a new Image model for each, then unshift that Image into my User's photos. I have Multer set up to successfully fills req.files. Here's the code.
router.post("/users/:user/photos/upload", middle.isLoggedIn, upload.array("photos", 4), function(req, res) {
User.findById(req.params.user, function(err, foundUser) {
for(var i = 0, len = req.files.length; i < len; i++) {
Image.create(req.files[i], function(err, newImage) {
if(err) {
return console.log(err.message);
}
newImage.human = foundUser;
newImage.save();
console.log(newImage);
foundUser.photos.unshift(newImage);
foundUser.save();
});
}
console.log(foundUser);
});
});
console.log(foundUser); seems to execute and print before console.log(newImage);
User Model
var mongoose = require("mongoose"),
passportLocalMongoose = require("passport-local-mongoose");
var UserSchema = new mongoose.Schema({
username: String,
password: String,
firstName: String,
lastName: String,
city: String,
photos: [
{
type: mongoose.Schema.Types.ObjectId,
ref: "Image"
}
]
});
HumanSchema.plugin(passportLocalMongoose);
module.exports = mongoose.model("User", UserSchema);
Image Model
var mongoose = require("mongoose");
var ImageSchema = new mongoose.Schema({
fieldname: String,
originalname: String,
mimetype: String,
filename: String,
destination: String,
size: Number,
path: String,
human: {
id: {
type: mongoose.Schema.Types.ObjectId,
ref: "Human"
}
}
});
module.exports = mongoose.model("Image", ImageSchema);
This is my first stackoverflow question so let me know if I didn't post enough code.
I think it have something to do with Image.create() being asynchronous, and I'm still trying to learn more about this and promises, but I still don't fully understand how it's relevant in my code.
Use Mongoose's promise support.
Promise.all allows you to resolve an array of promises.
async/await control flow for Promises.
I'm not sure your code as it is structured will work without a serial loop due the async code that can execute in any order. I'm not sure that triggering multiple foundUser.save()s on the same object at different times will work out very well. Holding database objects in memory for a long time can open up more concurrency data issues too.
The Bluebird promise library includes some additional helpers like Promise.each which will serially complete promises before the next starts which may be of use here.
const Promise = require('bluebird')
router.post("/users/:user/photos/upload", middle.isLoggedIn, upload.array("photos", 4), async function(req, res, next) {
try {
let foundUser = await User.findById(req.params.user)
await Promise.each(req.files, async file => {
let newImage = await Image.create(file)
newImage.human = foundUser;
await newImage.save()
console.log(newImage)
foundUser.photos.unshift(newImage)
await foundUser.save()
}
console.log(foundUser)
}
catch (err) {
next(err)
}
})
Other methods like .map and .reduce help make standard array/loop type operations with Promises easier to do.
Atomic Updates
In regards to the concurrency issue, any updates you can do in MongoDB that are "atomic" are a good thing. So instead of selecting something, modifying it in JS, then saving it back, you send the update to Mongo and let the db server deal with it. No matter what order you send the updates to the database, they will always be updating the latest copy of data.
In this case the array unshift can be completed without the initial select by using findByIdAndUpdate and $push (it can be made to push at position 0, there is no $unshift in mongo).
If you add a method to your User model for the adding the photo:
addPhoto(user_id, newImage){
return User.findByIdAndUpdate(
user_id,
{ $push: { photos: { $each: [newImage], $position: 0 } } } }
{ safe: true, new: true }
)
}
So the code would look like
const Promise = require('bluebird')
router.post("/users/:user/photos/upload", middle.isLoggedIn, upload.array("photos", 4), async function(req, res, next) {
try {
let foundUser = await User.findById(req.params.user)
if (!foundUser) throw new Error(`No user found: $user`)
let results = await Promise.map(req.files, async file => {
let newImage = await Image.create(file)
newImage.human = foundUser
await newImage.save()
console.log(newImage)
let user_update = await User.addPhoto(req.params.user, newImage)
console.log(user_update)
}
}
catch (err) {
next(err)
}
})
Related
I'm trying to update the document but the error says the query has already been executed.
MongooseError: Query was already executed: footballs.updateOne({ date: 'January 4' }, {})
app.post('/api/bookslot', async (req, res) => {
console.log(req.body);
try {
const token = req.headers['x-access-token'];
const decoded = jwt.verify(token, 'secret123');
const email = decoded.email;
const user = await UserModel.findOne({ email: email });
let sportname = req.body.selectedSport.toLowerCase();
const time = req.body.slotTime;
const seats = req.body.availableSeats - 1;
if (!sportname.endsWith('s')) {
sportname = sportname.concat('s');
}
const NewSlotModel = mongoose.model(sportname, slotSchema);
var update = {};
update[time] = seats - 1;
console.log(update);
const a = await NewSlotModel.updateOne(
{ date: req.body.slotDate },
{ $set: update },
function (err, success) {
if (err) return handleError(err);
}
);
return res.json({ status: 'ok' });
} catch (e) {
console.log(e);
res.json({ status: 'error' });
}
});
where am I going wrong?
You are using both async/await and callbacks in your code, causing mongoose to throw an error.
The actual effect of using them both is exactly the error type that you are receiving:
Query was already executed
Mongoose v6 does not allow duplicate queries.
Mongoose no longer allows executing the same query object twice. If
you do, you'll get a Query was already executed error. Executing the
same query instance twice is typically indicative of mixing callbacks
and promises, but if you need to execute the same query twice, you can
call Query#clone() to clone the query and re-execute it. See gh-7398
Duplicate Query Execution
To fix the issue, just remove the third argument from the await
NewSlotModel.updateOne
Making it:
const a = await NewSlotModel.updateOne(
{ date: req.body.slotDate },
{ $set: update }
);
Mongoose v6. Don't support callbacks any longer.. check the image.
const productCount = await Product.countDocuments((count) => count) BAD
const productCount = await Product.countDocuments(); GOOD
I am practicing my express.js skills by building a relational API and am struggling to populate keys in a schema.
I am building it so I have a list of properties, and those properties have units. The units have a propertyId key.
This is currently returning an empty array, whereas if i remove the populate({}) it returns an array of ObjectIds.
I've read a number of posts and some people solved this by using .populate({path: 'path', model: Model}); but this doesn't seem to be doing the trick. I think it might be the way I am adding a propertyId to the unit but I'm not sure. Can anyone see where I am going wrong? Any help will be massively appreciated.
Here are the schemas.
Property:
const mongoose = require('mongoose');
const { Schema } = mongoose;
const PropertySchema = new Schema({
title: {
type: String,
required: true
},
date: {
type: Date,
default: Date.now
},
units: [
{
type: mongoose.Schema.Types.ObjectId,
ref: 'unit'
}
]
});
module.exports = Property = mongoose.model('property', PropertySchema);
Unit:
const mongoose = require('mongoose');
const { Schema } = mongoose;
const UnitSchema = new Schema({
title: {
type: String,
required: true
},
propertyId: {
type: Schema.Types.ObjectId,
ref: 'property'
}
});
module.exports = Unit = mongoose.model('unit', UnitSchema);
I am then creating the unit like this:
-- api/properties/:id/units --
router.post('/:id/units', async (req, res) => {
// Get fields from req.body
const { title } = req.body;
// Get current property
const property = await Property.findById(req.params.id);
try {
// Throw error if no property
if (!property) {
return res.status(400).json({ msg: 'Property not found' });
}
// Create new unit
const newUnit = new Unit({
title,
propertyId: req.params.id
});
// Add new unit to property's units array
property.units.unshift(newUnit);
// Save property
await property.save();
// Return successful response
return res.status(200).json(property);
} catch (error) {
console.error(error.message);
return res.status(500).send('Server error');
}
});
And trying to populate in the GET request
-- /api/properties/:id/units --
const Unit = require('../../models/Unit');
router.get('/:id/units', async (req, res) => {
const property = await Property.findOne({ _id: req.params.id }).populate({path: 'units', model: Unit});
const propertyUnits = property.units;
return res.status(200).json(propertyUnits);
});
If i remove the .populate({path: 'units', model: Unit});, I get a list of unit id's like this:
[
"5ff7256cda2f5bfc1d2b9108",
"5ff72507acf9b6fb89f0fa4e",
"5ff724e41393c7fb5a667dc8",
"5ff721f35c73daf6d0cb5eff",
"5ff721eb5c73daf6d0cb5efe",
"5ff7215332d302f5ffa67413"
]
I don't know, why you don't try it like this:
await Property.findOne({ _id: req.params.id }).populate('units')
I've been try that code above and it's working.
Note: Make sure to check your req.params.id is not null or undefined and make sure the data you find is not empty in your mongodb.
Updated: I've been try your code and it's working fine.
The issue was caused by inconsistent naming and not saving the new created unit as well as the updated property.
I double checked all my schema exports and references and noticed I was using UpperCase in some instances and LowerCase in others, and saved the newUnit as well as the updated property in the POST request and it worked.
I'm trying to save some objects into an array by looping through a list of songs in an album, looking for relevant songs and trying to save into array for later use. is there any way to achieve this?
I need some explanation using mongoose.
exports.playlistPlayer = function (req, res, next) {
Playlist.findById({
_id: req.body.playlist._id
}, (err, playlist) => {
var customAlbum = []; //This variable it's inside the same block i believe
playlist.songs.forEach(function (song) {
Song.findById({
_id: song.song_id
}, (err, songs) => {
var customSong = {
title: songs.title,
time: songs.time,
source: songs.source,
song_id: songs._id
}
customAlbum.push(customSong)
console.log(customAlbum) //it works here
});
});
console.log(customAlbum) //it returns an empty array here where i need the data
});
};
The problem is that the findById method is also asynchronous. I recommend you to learn about promises in javascript. One possible solution would be using the async/await feature from ES7:
// asynchronous function
exports.playlistPlayer = async (req, res, next) => {
// wait for the findById method promise to resolve
const playlist = await Playlist.findById({
_id: req.body.playlist._id
})
// wait for finding all songs in db whose id's are in
// the playlist.songs array
const songs = await Song.find({
_id: { $in: playlist.songs }
})
// create the customAlbum by using the map method to
// tramsform the song objects to the required form
const customAlbum = songs.map(song => ({
title: song.title,
time: song.time,
source: song.source,
song_id: song._id
}))
// and there you should now have your customAlbum array
console.log(customAlbum)
// now you can use it for example
// to return a response to the client:
// res.json(customAlbum)
}
I am using mongoose with Mongodb v3.4.3
Below is my image model code
const mongoose = require("mongoose");
const CoordinateSchema = require("./coordinate");
const ImageSchema = new mongoose.Schema({
image_filename: {
type: String,
required: true
},
image_url: {
type: String,
required: true
},
coordinates: [CoordinateSchema],
});
Below is my CoordinateSchema code
const mongoose = require("mongoose");
const CoordinateSchema = new mongoose.Schema({
coordinates : {
type: Array,
default: [],
}
});
module.exports = CoordinateSchema;
Below is my api js code running on express,
router.post('/receiveCoordinates.json', (req, res, next) => {
Image.findOneAndUpdate({image_filename:req.body.file_name}).then((image) => {
})
});
How to finish this code so I can store coordinates data in Image model.
Thanks.
UPDATE
To update the coordinates inside of findOneAndUpdate, you simply check that the returned document isn't undefined (which would mean your image wasn't found). Modify your api.js code like so:
router.post('/receiveCoordinates.json', (req, res, next) => {
Image.findOneAndUpdate({image_filename:req.body.file_name}).then((image) => {
if (!image) return Promise.reject(); //Image not found, reject the promise
image.where({_id: parent.children.id(_id)}).update({coordinates: req.body.coordinates}) //Needs to be an array
.then((coords) => {
if (!coords) return Promise.reject();
//If you reach this point, everything went as expected
});
}).catch(() => {
console.log('Error occurred');
);
});
Here's my guess why it isn't working.
In ImageSchema, you are sub-nesting an array of CoordinateSchema. But CoordinateSchema is a document which already contains an array.
This is probably not what you're looking for. If you're using mongoose version 4.2.0 or higher, you can nest CoordinateSchema inside of ImageSchema as a single document. Re-write your ImageSchema like this:
// ...
const ImageSchema = new mongoose.Schema({
// ...
coordinates: CoordinateSchema,
});
If this didn't work or doesn't resolve your issue, please let me know so we can work together to find a solution.
I am building a website using Node.js and Sequelize (with a Postgres backend). I have a query that returns many objects with a foreign key, and I want to pass to the view a list of the objects that the foreign key references.
In the example, Attendances contains Hackathon keys, and I want to return a list of hackathons. Since the code is async, the following thing of course does not work in Node:
models.Attendance.findAll({
where: {
UserId: req.user.id
}
}).then(function (data) {
var hacks = [];
for (var d in data) {
models.Hackathon.findOne({
where: {
id: data[d].id
}
}).then(function (data1) {
hacks.append(data1);
});
}
res.render('dashboard/index.ejs', {title: 'My Hackathons', user: req.user, hacks: hacks});
});
Is there any way to do that query in a synchronous way, meaning that I don't return the view untill I have the "hacks" list filled with all the objects?
Thanks!
Use Promise.all to execute all of your queries then call the next function.
models.Attendance.findAll({
where: {
UserId: req.user.id
}
}).then(function (data) {
// get an array of the data keys, (not sure if you need to do this)
// it is unclear whether data is an object of users or an array. I assume
// it's an object as you used a `for in` loop
const keys = Object.keys(data)
// map the data keys to [Promise(query), Promise(query), {...}]
const hacks = keys.map((d) => {
return models.Hackathon.findOne({
where: {
id: data[d].id
}
})
})
// user Promise.all to resolve all of the promises asynchronously
Promise.all(hacks)
// this will be called once all promises have resolved so
// you can modify your data. it will be an array of the returned values
.then((users) => {
const [user1, user2, {...}] = users
res.render('dashboard/index.ejs', {
title: 'My Hackathons',
user: req.user,
hacks: users
});
})
});
The Sequelize library has the include parameter which merges models in one call. Adjust your where statement to bring the Hackathons model into Attendance. If this does not work, take the necessary time to setup Sequelize correctly, their documentation is constantly being improved. In the end, you'll save loads of time by reducing error and making your code readable for other programmers.
Look how much cleaner this can be...
models.Attendance.findAll({
include: [{
model: Hackathon,
as: 'hackathon'
},
where: {
UserId: req.user.id
}
}).then(function (data) {
// hackathon id
console.log(data.hackathon.id)
// attendance id
console.log(data.id)
})
Also..
Hackathon.belongsTo(Attendance)
Attendance.hasMany(Hackathon)
sequelize.sync().then(() => {
// this is where we continue ...
})
Learn more about Sequelize includes here:
http://docs.sequelizejs.com/en/latest/docs/models-usage/
Immediately invoke asynchronous function expression
This is one of the techniques mentioned at: How can I use async/await at the top level? Toplevel await is likely coming soon as of 2021, which will be even better.
Minimal runnable example:
const assert = require('assert');
const { Sequelize, DataTypes } = require('sequelize');
const sequelize = new Sequelize({
dialect: 'sqlite',
storage: 'db.sqlite',
});
const IntegerNames = sequelize.define(
'IntegerNames', {
value: { type: DataTypes.INTEGER, allowNull: false },
name: { type: DataTypes.STRING, },
}, {});
(async () => {
await IntegerNames.sync({force: true})
await IntegerNames.create({value: 2, name: 'two'});
await IntegerNames.create({value: 3, name: 'three'});
await IntegerNames.create({value: 5, name: 'five'});
// Fill array.
let integerNames = [];
integerNames.push(await IntegerNames.findOne({
where: {value: 2}
}));
integerNames.push(await IntegerNames.findOne({
where: {value: 3}
}));
// Use array.
assert(integerNames[0].name === 'two');
assert(integerNames[1].name === 'three');
await sequelize.close();
})();
Tested on Node v14.16.0, sequelize 6.6.2, seqlite3 5.0.2, Ubuntu 20.10.