Checking documents from MongoDb with if(==) operator in NodeJs - node.js

Question

I have problem how to check specific document from MongoDb in NodeJs with if operator.
My MongoDb collection looks liket this (I only need document "button"):
{
"_id" : ObjectId("5e95eb9da19c2430d4952754"),
"title" : "Krepšinis",
"author" : "5e90eb1abbcb1f33e8b17720",
"place" : "dsadas",
"count" : 10,
"going_count" : 5,
"button" : "Būsiu",
"__v" : 0
}
My NodeJs:
router.post('/:id', function(req, res){
let post = {};
if(post.button == "Būsiu"){
post.button = "Nebūsiu";
} else {
post.button = "Būsiu";
}
let query = {_id:req.params.id}
Post.update(query, post, function(err){
if(err){
console.log(err);
return;
}
req.flash('success', 'Postas Atnaujintas');
res.send('Success');
});
});
The problem is I don't get any errors, it just doesn't work.
And this is my Ajax:
$(document).ready(function(){
$('.going').on('click', function(e){
console.log('working')
$target = $(e.target);
const id = ($target.attr('data-id'));
$.ajax({
type:'POST',
url: '/posts/'+id,
success: function(response){
alert('Važiuojam');
},
error: function(err){
console.log(err);
}
});
});
});
I don't really know what to try else, because I'm pretty new to programming.

Answer 1

Can you try specifying the mongodb aggregation pipeline and check what the result of affected documents in the query is as below
router.post('/:id', function(req, res){
let post= {};
if(post.button == "Būsiu"){
post.button = "Nebūsiu";
} else {
post.button = "Būsiu";
}
let query = {_id:req.params.id}
Post.update(query, {$set:post}, function(err, response
){
if(err){
console.log(err);
return;
}
console.log(response.result.nModified)
req.flash('success', 'Postas Atnaujintas');
res.send('Success');
});
});