Using two collection in MongoDB with Mongoose - node.js

Question

I'm new to NodeJS, and I'm using the following:
Express
Mongoose
passport
HI I have two collections in MongoDB, they both have nothing to do with each other, they're called:
Post
and
User
In a get route for /home in an IF statement I am trying to query information from both collections and render them in an EJS page. My initial thoughts were create find for one model store in a var, then use it in another function when rendering the page.
Here is the relevant code:
app.get("/home", function(req, res){
console.log(req.user._id);
if (req.isAuthenticated()){
// //*Find current logged in user details
User.find({_id: req.user._id}, function(err, users){
var currentUserName = req.user.name
});
//*end
Post.find({}, function(err, posts){
res.render("home", {
startingContent: homeStartingContent,
posts: posts,
currentUser: currentUserName
});
});
} else {
res.redirect("login")
}
});
At the start of my js file, i have declared
var currentUserName
But its not displaying the value in the home.ejs for:
<p><%= currentUser %></p>
Its just blank.
What am I doing wrong here? I thought using var would make it a global variable and then can be used in another function? Other posts have suggested a aggregate, but these collections are completely seperate and have nothing to do with each other.

Answer 1

You have defined currentUserName inside User.find(){...} function and it is accessible only within that function. You need to define the variable that can be block-scoped, outside User.find(){...} function. Check the code snippet below:
app.get("/home", function(req, res){
console.log(req.user._id);
if (req.isAuthenticated()){
let currentUserName;
// //*Find current logged in user details
User.find({_id: req.user._id}, function(err, users){
currentUserName = req.user.name
});
//*end
Post.find({}, function(err, posts){
res.render("home", {
startingContent: homeStartingContent,
posts: posts,
currentUser: currentUserName
});
});
} else {
res.redirect("login")
}
});
Javascript best practices tells that it is better to use let instead of var. Variables declared by var keyword are scoped to the immediate function body i.e. User.find(){...} while let variables are scoped to the immediate enclosing block denoted by { }, i.e. if(req.isAuthenticated()){...}.

Answer 2

It won't work, because every variable has scope. Scope means access to use that var. In this case currentUserName has scope or can be used only in User.find() section. If you want to use it in Post.find(), then do it by declaring it in main function as below.
app.get("/home", function(req, res){
console.log(req.user._id);
let currentUserName;
if (req.isAuthenticated()){
User.find({_id: req.user._id}, function(err, users){
currentUserName = req.user.name
});
Post.find({}, function(err, posts){
res.render("home", {
startingContent: homeStartingContent,
posts: posts,
currentUser: currentUserName
});
});
} else {
res.redirect("login")
}
});
It will work as you require by declaring currentUserName in main function, so it will be used in whole main app.get() function