moment-play.js

        var expiration = '0000-00-00 00:00:00';
        if (body.expiration !== undefined) {
            var arr = body.expiration;
            //check to make sure it is an array
            if (!Array.isArray(arr)) {
                def.reject('expiration property is not a valid array');
                return def.promise;
            }
            //check to make sure it is of the right length [d,h,m,s]
            if (arr.length !== 4) {
                def.reject('expiration array must have a length of 4');
                return def.promise;
            }
            //validate each parameter
            for (var i = 0; i < arr.length; i++) {
                if (typeof arr[i] !== 'number' ||
                    typeof arr[i] === 'number' && arr[i] % 1 !== 0) {
                    def.reject('illegal index in expiration array');
                    return def.promise;
                }
            }
            //construct the datetime string we use in query
            var now = moment();

            if (arr[0] > 0) now.add(arr[0], 'days');
            if (arr[1] > 0) now.add(arr[1], 'hours');
            if (arr[2] > 0) now.add(arr[2], 'minutes');
            if (arr[3] > 0) now.add(arr[3], 'seconds');

            expiration = now.format('YYYY-MM-DD HH:mm:ss');
        }

Where does the local 'expiration' go after you assign to it?