javascript - How can I properly promisify these two database methods for nodejs? -

i have database module handles connection setup , pooling, , query module relies on database module execute queries. i'm adapting both of them use promises asynchronous calls. far, i've adapted query module - wish convert database module.

here's problem: database module should usable both directly , implicitly query module (which relies on callbacks). how can use promises in both modules' methods without turning maze of twisty little passages?

here's i've done far:

database module

getconnection: function(callback) { //this should return promise     this.pool.getconnection(function(error, connection){         callback(error, connection);     }); }, 

query module should then on getconnection promise, execute query, , reject/resolve it's caller

    request: function(queryrequest) {         return new promise(function(resolve, reject){             database.getconnection(function(error, connection){                 if(error) {                     reject({error: error, queryrequest: queryrequest});                 } else {                     connection.query(queryrequest.sql, queryrequest.values, function(error, rows, fields){                         if(error) {                             reject({error: error, queryrequest: queryrequest});                         } else {                             resolve({rows: rows, fields: fields, queryrequest: queryrequest});                         }                         connection.release()                     });                 }             });         });     }, 

getconnection should return promise [for connection]

rather not, should use disposer pattern instead, , call connection.release() itself:

function withconnection(callback) {     var pool = this.pool;     var conn = new promise(function(resolve, reject) {         pool.getconnection(function(error, connection){             if (error)                 reject(error);             else                 resolve(connection);         });     });     return conn.then(function(connection) {         var res = conn.then(callback); // safe call         return res.then(fin); // `finally` shim         function fin() {             connection.release();             return res;         }     }); }  function request(queryrequest) {     return database.withconnection(function(connection) {         return new promise(function(resolve, reject) {             connection.query(queryrequest.sql, queryrequest.values, function(error, rows, fields) {                 if (error)                     reject(error);                 else                     resolve({rows: rows, fields: fields, queryrequest: queryrequest});             });         });     }).catch(function(error) {         error.queryrequest = queryrequest;         throw error;     }); }