On the following post method, I'm having some issues due to moongose async. res.send(suggestions) is executed first then Expense.findOne.exec
app.post('/suggestions', async function(req, res) {
const suggestions = await req.body.map((description) => {
Expense.findOne({ description: new RegExp(description, 'i') }).exec((err, result) => {
if (result) {
console.log(result.newDescription);
return {
description,
newDescription: result.newDescription,
category: result.category,
subcategory: result.subcategory
};
}
});
});
res.send(suggestions);
});
The result is a array of null values. How can I executed a query for each item, then execute res.send(suggestion)?
Found solution with the following code:
app.post('/suggestions', async function(req, res) {
try {
if (req.body.length > 0) {
const suggestions = req.body.map((description) =>
Expense.findOne({ description: new RegExp(description, 'i') })
);
const results = await Promise.all(suggestions);
return res.send(results);
}
} catch (e) {
console.log('error', e);
}
});
Related
I am trying to push the fetched data in an array using foreach but it only returns the first data in the loop. Here is my code.
exports.getAllTrial = async function (req, res, next) {
try {
new Promise( async (resolve, reject) => {
var reservations = [];
await Schedule.getSchedule()
.then(data => {
data.forEach(async (element) => {
await saveReserve.getAllTrial({where: {scheduleID: element.id, date: "8/18/2020"}})
.then(trial => {
trial.forEach(response => {
reservations.push(response.scheduleID)
})
})
console.log(reservations);
resolve(reservations);
})
});
})
.then(value=>{
res.status(200).json(value);
})
.catch(err => {
console.log(err);
});
} catch (e) {
return res.status(400).json({ status: 400, message: e.message });
}
}
My expected output should be: [ 9, 10, 10 ] But it only returns [9].
Async code in a foreach loop is a bad idea, as it won't be executed one after the other. I suggest reading a bit more async/await and the concept of promise, as you are mixing things here (such as mixing await and .then). Also worth looking into Promise.all which will resolve a list of promises and array.map.
While I have no idea of what some variables such as saveReserve are supposed to be or do, your code might be simplified into:
exports.getAllTrial = async (req, res, next) => {
try {
const data = await Schedule.getSchedule()
const reservations = await Promise.all(
data.map(element => {
return saveReserve.getAllTrial({ where: { scheduleID: element.id, date: '8/18/2020' } })
})
)
return res.status(200).json(reservations)
} catch (e) {
return res.status(400).json({ status: 400, message: e.message })
}
}
I've a mongoose schema in which a virtual property is defined:
mortSchema.virtual('count').get(function () {
return Pickup.countDocuments({ mortician: this._id }).exec().then((count) => { console.log(count) })
})
I'm rendering it using express like this:
try {
const morticians = await Mortician.find({})
res.render('morticians', {
title: 'Mortician',
morticians: morticians
})
console.log(await morticians.count)
} catch (err) { /* err */ }
Since the promise it not solved at rendering time, it's outputting Promise { <pending> }, before the then() function to the console. How to solve the promise, before passing it to res.render? Where to insert the missing await?
Workaround: Removing the virtual property from the schema like this is working, but not answering my question:
try {
const morticians = await Mortician.find({})
for (mortician of morticians)
await Pickup.countDocuments({ mortician: mortician._id },
(err, count) => { mortician.count = count })
res.render('morticians', {
title: 'Mortician',
morticians: morticians
})
} catch (err) { /* err */ }
I want to refactor code for chain of promises by async, await. I have sequelize ORM for DB management and the code is written in AWS Lambda function having multiple middleware. In such cases I have to traverse code for multiple entries using sequelize transactions. It is easy to manage using promise.all() but need to change it to async await syntax for cleaner code.
Here are my demo code.
/* get all invoice where user_id === current logged in user, and where status != "paid" */
db.Invoice.findAll({
where: {
user_id: currentLoggedInUser,
status: {
$ne: "paid"
}
}
}).then(invoices => {
if (!invoices || invoices === null) {
return false;
}
function addScheduledTransactionAttempts(invoice, tryPayOnDate, t) {
return new Promise((resolve, reject) => {
/* check If any ScheduledTransactionAttempts exists for this invoice.id */
db.ScheduledTransactionAttempts.find({
where: {
invoice_id: invoice.id
}
})
.then(function(attempts) {
if (attempts) {
attempts
.destroy({}, {
transaction: t
})
.then(deletedAttempts => {
console.log("Attempts Record Deleted: ", deletedAttempts);
})
.catch(error => {
reject(error);
t.rollback();
});
}
return db.ScheduledTransactionAttempts.create({
invoice_id: invoice.id,
payment_source_id: PaymentMethodId,
try_pay_on_date: tryPayOnDate,
stripe_customer_id: currentLogInStripeCustomerId
}, {
transaction: t
})
.then(function(attempt) {
resolve(attempt.id);
})
.catch(error => {
reject(error);
t.rollback();
});
})
.catch(error => {
reject(error);
t.rollback();
});
});
}
//Run transaction to addScheduledTransactionAttempts
return db.sequelize.transaction().then(function(t) {
let promiseArr = [];
var i = 0;
invoices.forEach(function(invoice) {
var schedulePaymentDate = moment(paymentDate);
if (invoice) {
let tryPayOnDate = schedulePaymentDate
.add(i, "month")
.format("YYYY-MM-DD");
promiseArr.push(
addScheduledTransactionAttempts(invoice, tryPayOnDate, t) //calling above function
);
i++;
}
});
//now execute promise all
Promise.all(promiseArr)
.then(function(result) {
t.commit();
return true;
})
.catch(function(err) {
t.rollback();
return false;
});
});
});
In the above code I want to change
Promise.all(promiseArr)
which is calling
addScheduledTransactionAttempts
function to do DB queries to simple async function await process to make it easy simpler understandable without having multiple .then or .then inside then promises.
Any help regarding would be appreciated,
Thanks.
It's quite simple. await is valid when invoking methods that return a Promise. All of your SDK methods already return a promise, so refactoring should be quite straight forward. Here's something to get you off ground:
const processInvoices = async currentLoggedInUser {
const invoices = await db.Invoice.findAll({
where: {
user_id: currentLoggedInUser,
status: {
$ne: 'paid',
},
},
});
if (yourOwnLogicForInvoicesObject) {
for (const invoice of invoices) {
const potentiallyFoundInvoice = await db.ScheduledTransactionAttempts.find({
where: {
invoice_id: invoice.id,
},
});
if (potentiallyFoundInvoice) {
await addScheduledTransactionAttempts(potentiallyFoundInvoice)
}
}
}
}
const addScheduledTransactionAttempts = async invoice => {
console.log('Do something with your invoice', invoice)
}
Long story short: refactor the code inside your functions into smaller functions and make these new functions async, just like I did with addScheduledTransactionAttempts and processInvoices
More on async/await
Im trying to build a rest api, fetching a nested mysql queries.
When i fetch the first query, this return a array, then with this array i need to fetch data with another query for each value through a array.map
when the script running, always log a empty array, i think must be cause of promises. any help please?
//this the mysql queries
const getTournaments = 'SELECT ID FROM wp_posts WHERE post_type = "tournament"'
const getTournamentGame = 'SELECT meta_value FROM wp_postmeta WHERE meta_key = "tournament_game" AND post_id = ?'
async function fetchType(id){
return new Promise ((res, rej) => {
try{
pool.query(getTournamentGame, [id], (err, rows) => {
if (err) {
return rej(err)
}else {
return res(rows[0].meta_value)
}
})
} catch(err){
console.log(err)
}
})
}
async function mapeado(array) {
return new Promise (async (resolve,rej) => {
try{
var arr = []
array.map((item) => {
fetchType(item.ID).then((res) => {
var tourData = {
id: item.ID,
type: res
}
return tourData
}).then((data) => {
arr.push(data)
})
})
return resolve(arr)
} catch(err) {
console.log(err)
}
})
}
//making rest api
app.get('/tournaments', async (req, res) => {
pool.query(getTournaments, (err, rows) => {
mapeado(rows).then(console.log)
})
})
I've been reading some CRUD / Mongoose guides, but haven't a good explainer for conditionally updating fields.
So for example, an action called updateItem is used in one place to update item.price but in another place it updates item.color. Does anyone know a good explanation or tutorial for Mongoose CRUD APIs that shows this?
I'm getting the blow code to work fine, but I have a feeling it could be cleaner :)
Thanks!!!
router.put('/tasks/:id', (req, res) => {
Task.findByIdAndUpdate(req.params.id,
req.body.owner ? { owner: req.body.owner } : { hours: req.body.hours }, { new: true })
.then(task => {
res.status(201).json(task)
})
.catch(err => {
console.log('Our error', err)
})
});
Another approach you could take is to first retrieve the object, and then only update the value if it is passed into the put request. An example of that could be something like this:
router.put('/tasks/:id', (req, res) => {
let price = req.body.price;
let color = req.body.color;
Task.findById(req.params.id, function (err, task) {
if (err) return handleError(err);
task.color = color || task.color;
task.price = price || task.price;
task.save(function(err, updatedTask) {
if err return handleError(err);
return res.send(updatedTask);
});
});
});
Here's another cleaner approach using async-await functions:
// Import promisify from utils
const promisify = require('utils').promisify;
// Wrap findByIdAndUpdate into a promise
const updateOwnerPromise = promisify(Task.findByIdAndUpdate);
// Write an async handler now
updateOwnerPromiseAsync = async (req, res) => {
const replacementObject = req.body.owner ? { owner: req.body.owner } : { hours: req.body.hours };
try {
await updateOwnerPromise(replacementObject, { new:true} );
return res.status(200).send({ message: 'Owner updated successfully!' });
} catch(err) {
// TODO: handle error here
console.log('Our error', err)
return res.status(500).send({ message: 'Failed to update owner, because of some issue at the server!' });
}
}
// Modify the express route with the handler
router.put('/tasks/:id', updateOwnerPromiseAsync);