Node.js错误TypeError：对象不是回调函数

Question

Ok guys..i've been staring at this code and i just don't see the error in my code. My code is connecting to the DB fine and my console log is showing my results as

{ id: 7,
name: 'Tap\'s',
quicklist: 'Y',
message: 'Welcome..enjoy one of our many craft brews!',
fbflag: 'Y',
facebookurl: 'https://www.facebook.com/TapsPourhouseMooresville',
twflag: 'Y',
twitterurl: 'https://twitter.com/TapsPourhouse',
contactflag: 'Y',
contactemail: 'info@blazingpoint.com',
eventsflag: 'Y',
loyaltyflag: 'Y',
loyaltyclub: 'TAPped In',
loyaltymessage: 'Become a member of the TAPped In Club in order to receive special offers and to stay informed on upcoming events and exclusive offers!',
locdescription: 'Table 10' }

which is what i am wanting to get returned back but I keep getting TypeError: object is not a function referring to line commented below.

exports.get_site_setup = function (callback) {
var dbc;

async.waterfall([
    // get a connection
    function (cb) {
//           if (!name)
//               cb(backhelp.missing_data("site name"));
//           else
              db.db(cb);
    },

    function (dbclient, cb) {
        dbc = dbclient;
        dbc.query("select s.ID as id, s.NAME as name, s.QUICK_LIST_ENABLED as quicklist, s.MESSAGE as message, s.FBFLAG as fbflag, "+
                "s.FACEBOOKURL as facebookurl, s.TWFLAG as twflag, s.TWITTERURL as twitterurl, "+
                "s.CONTACTFLAG as contactflag, s.CONTACTEMAIL as contactemail, s.EVENTSFLAG as eventsflag, "+
                "s.LOYALTYFLAG as loyaltyflag, s.LOYALTYCLUB as loyaltyclub, s.LOYALTYMESSAGE as loyaltymessage, l.LOCDESC locdescription "+
                "from COMPANIES as c "+
                "left join SITES as s on c.ID = s.COMPANY_ID "+
                "left join LOCATION as l on s.ID = l.SITE_ID "+
                "where c.ID = 7 and s.ID = 7 and l.ID = 8",
                cb);
    }

],
function (err, results) {
    if (dbc) {dbc.end();}
    if (err) {
       callback(err);
    } else if (!results || results.length === 0) {
       // callback(backhelp.no_such_site());
    } else {
        callback(null, results[0]); //  <-- Error on this line
        console.log(results[0]);
    }
});
};

Answer 1

If you review the documentation for waterfall you will see that the callbacks get called in the order of the array and the final function(err, results) is called once all elements of the array have been processed.

https://github.com/caolan/async#waterfall

So in your first callback

 function (cb) {
//           if (!name)
//               cb(backhelp.missing_data("site name"));
//           else
              db.db(cb);
    },

When you reference db.db(cb); is that function calling cb( null, dbclient, cb) to go to the next function specified in your array?

Then in the second function where dbc.query happens you will need to be sure the query calls cb( null, expected result);

The null indicates to waterfall that there is no error and to continue.

Also your results variable may be a string and not an array. Please check that. As this test would pass if it was a string (likely your problem.

} else if (!results || results.length === 0) {