node-mysql where does connection.end() go

Question

I am really confused with using connection.end() in node-mysql.

I don't fully understand where it goes, at the moment i place it after a query but then if i create a new query i get an error Cannot enqueue Query after invoking quit.

Now my app has a bunch of checks going here is one of them:

   socket.on('connect', function(data,callBack){
       var session = sanitize(data['session']).escape();                    

       var query = connection.query('SELECT uid FROM sessions WHERE id = ?', [session],
           function(err,results){
           if(err){ 
                  console.log('Oh No! '+err);                   
              }else{
                  io.sockets.socket(socket.id).emit('connectConfirm',{data : true});
              }
              connection.end();
           });
   });

Now after that if i have any other query i get the error occuring.

I made a more informed explaination in my jsFiddle: http://jsfiddle.net/K2FBk/ to better explain the problem I'm getting. The documentation for node-mysql does not totally explain the correct place to put connection.end()

Where should it go to avoid this error?

score 21 · Accepted Answer · answered Dec 19 '13 at 22:41

21

Per the documentation:

Closing the connection is done using end() which makes sure all remaining queries are executed before sending a quit packet to the mysql server.

connection.end() is then supposed to be called only when you stop sending queries to MySQL, i.e. when your application is stopping. You shouldn't create/end connections all the time: just use the same connection for all your queries (or use a connection pool to be more efficient).

answered Dec 19 '13 at 22:41

Paul Mougel

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Thanks for the reply, so in my JSFiddle code would i simply put it on line number 75? =/ Or does it still have to be within the app connection... this is what i found confusing. – Sir Dec 19 '13 at 22:44
2

You'd close the connection when your application stops. If you stop it using the control-c keys, then [look at this answer](http://stackoverflow.com/a/9299388/2137601) and put the `connection.close()` there. – Paul Mougel Dec 19 '13 at 22:58
Oh so i need to call `connect.end()` from an event check such as ctrl-c – Sir Dec 19 '13 at 23:00
@PaulMougel can you please help on this thread, I'm using a singleton pattern for the mysqlconnection, I never call end on connection and keep on reusing it throughout the life of the app, however, I'm concerned with timeout setting, i.e. mysql killing the connection on inactivity http://stackoverflow.com/questions/26533936/node-js-mysql-connection-via-a-singleton – user2727195 Oct 23 '14 at 17:55

score 1 · Answer 2 · answered Jun 23 '17 at 06:29

socket.on('connect', function(data,callBack){
       var session = sanitize(data['session']).escape();                    

       var query = connection.query('SELECT uid FROM sessions WHERE id = ?', [session],
           function(err,results){
           if(err){ 
                  console.log('Oh No! '+err);                   
              }else{
                  io.sockets.socket(socket.id).emit('connectConfirm',{data : true});
              }

           });

       connection.end(); // close connection outside the callback
   });

Its giving error because you are closing connection during en-queue

node-mysql where does connection.end() go

2 Answers2

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