How can I update mongoose subdocuments via form post request - node.js

Question

I have a Schema system with nested schemas to create a one to many relationship.
User Schema
const expenseSchema = new Schema({
expense: String,
value: Number
});
const budgetSchema = new Schema({
earnings: Number,
expenses: [expenseSchema]
});
const userSchema = new Schema({
username: String,
name: String,
googleId: String,
budget: [budgetSchema]
});
I am trying to push a value to these nested schemas but been having some trouble. Note The req.user value is of authenticated users through Passport authentication
This is my attempt to add data into the budget schema's earning property. The weird thing is that when I log the user after the post request it shows undefined.
router.post("/", (req, res) => {
User.findOneAndUpdate(req.user, {
$push: {
budget: {
earnings: req.body.earning
}
}
});
console.log(req.user);
});
Vue form
submitBudget() {
const expenses = this.mergeKeyAndValue();
axios
.post("http://localhost:3000/budget", {
earning: this.earnings,
expenses
})
.then(response => {
console.log(response.data);
})
.catch(e => {
console.error(e);
});
}

Answer 1

router.post("/", (req, res) => {
User.findOneAndUpdate(req.user,
{$push:{
budget: {
earnings: req.body.earning
}
}
}
)
console.log(req.user);
})
In here, you are not providing a callback function to User.findOneAndUpdate() and without such function, all you're doing is querying the database without saving anything.
Taken from Mongoose docs about Model.findOneAndUpdate()
A.findOneAndUpdate(conditions, update, options, callback) // executes
A.findOneAndUpdate(conditions, update, options) // returns Query
A.findOneAndUpdate(conditions, update, callback) // executes
A.findOneAndUpdate(conditions, update) // returns Query -> This is what you are doing right now.
A.findOneAndUpdate() // returns Query
Additionally, your syntax is incorrect that's probably why you're getting undefined. It should be Users.findOneAndUpdate({ username: req.user },..... or wherever your req.user username key the request object holds is stored.
You can rewrite the whole function using async/await in the following way:
router.post("/", async (req, res) => {
const update = await User.findOneAndUpdate(
{ username: req.user.username },
{
$push: {
budget: {
earnings: req.body.earning
}
}
}
)
console.log(update);
});
I don't have an easy way to test the $push update so I'm going to assume you know what you are doing but the rest should be as described.