Meteor: Increment DB value server side when client views page - mongodb

Question

I'm trying to do something seemingly simple, update a views counter in MongoDB every time the value is fetched.
For example I've tried it with this method.
Meteor.methods({
'messages.get'(messageId) {
check(messageId, String);
if (Meteor.isServer) {
var message = Messages.findOne(
{_id: messageId}
);
var views = message.views;
// Increment views value
Messages.update(
messageId,
{ $set: { views: views++ }}
);
}
return Messages.findOne(
{_id: messageId}
);
},
});
But I can't get it to work the way I intend. For example the if(Meteor.isServer) code is useless because it's not actually executed on the server.
Also the value doesn't seem to be available after findOne is called, so it's likely async but findOne has no callback feature.
I don't want clients to control this part, which is why I'm trying to do it server side, but it needs to execute everytime the client fetches the value. Which sounds hard since the client has subscribed to the data already.
Edit: This is the updated method after reading the answers here.
'messages.get'(messageId) {
check(messageId, String);
Messages.update(
messageId,
{ $inc: { views: 1 }}
);
return Messages.findOne(
{_id: messageId}
);
},

Answer 1

For example the if(Meteor.isServer) code is useless because it's not
actually executed on the server.
Meteor methods are always executed on the server. You can call them from the client (with callback) but the execution happens server side.
Also the value doesn't seem to be available after findOne is called,
so it's likely async but findOne has no callback feature.
You don't need to call it twice. See the code below:
Meteor.methods({
'messages.get'(messageId) {
check(messageId, String);
var message = Messages.findOne({_id:messageId});
if (message) {
// Increment views value on current doc
message.views++;
// Update by current doc
Messages.update(messageId,{ $set: { views: message.views }});
}
// return current doc or null if not found
return message;
},
});
You can call that by your client like:
Meteor.call('messages.get', 'myMessageId01234', function(err, res) {
if (err || !res) {
// handle err, if res is empty, there is no message found
}
console.log(res); // your message
});
Two additions here:
You may split messages and views into separate collections for sake of scalability and encapsulation of data. If your publication method does not restrict to public fields, then the client, who asks for messages also receives the view count. This may work for now but may violate on a larger scale some (future upcoming) access rules.

Answer 2

views++ means:
Use the current value of views, i.e. build the modifier with the current (unmodified) value.
Increment the value of views, which is no longer useful in your case because you do not use that variable for anything else.
Avoid these increment operator if you are not clear how they exactly work.
Why not just using a mongo $inc operator that could avoid having to retrieve the previous value?