Node.js:如何以最简单的方式将util.promisify应用于mysql池?
我看到了another thread和后Create a MySQL Database Middleware with Node.js 8 and Async/Await,但是现在我只想以最简单和最直接的方式使用util.promisify
,我可以想到,将它应用到mysql连接池。关于Node.js documentation,bellow是我的代码snipet:
exports.genAdminCfg = function (app) {
let sql = 'SELECT * FROM nav_tree;';
let pool = require('mysql').createPool({
host: 'localhost',
user: 'root',
password: 'mysql',
database: 'n4_ctrl',
connectionLimit: 4,
multipleStatements: true
});
/* --- Works fine without "promisify":
pool.query(sql, function (err, rows) {
if (err) {
console.log(err);
return err;
} else {
app.locals.adminCfg = genCfg(rows);
app.locals.adminCfg.dbConnectionPool = pool;
}
});
*/
/* --- Does not worke with "promisify":
TypeError: Cannot read property 'connectionConfig' of undefined
at Pool.query (/usr/home/zipper/node/n4.live/node_modules/mysql/lib/Pool.js:194:33)
*/
require('util').promisify(pool.query)(sql).then(function (rows) {
app.locals.adminCfg = genCfg(rows);
app.locals.adminCfg.dbConnectionPool = pool;
}, function (error) {
console.log(error);
});
};
我评论的代码在没有promisify
的情况下工作正常。但是与promisify
相邻的类似代码不起作用并显示TypeError: Cannot read property 'connectionConfig' of undefined
。代码有什么问题?
node version = v8.1.4
回答如下:除非另有证明,否则始终应该预期方法依赖于上下文。
由于pool.query
是一种方法,它应该被绑定到正确的上下文:
const query = promisify(pool.query).bind(pool);
这可能是不必要的,因为大多数流行的图书馆都有基于承诺的替代方案,可以利用承诺,including mysql
。
Node.js:如何以最简单的方式将util.promisify应用于mysql池?
我看到了another thread和后Create a MySQL Database Middleware with Node.js 8 and Async/Await,但是现在我只想以最简单和最直接的方式使用util.promisify
,我可以想到,将它应用到mysql连接池。关于Node.js documentation,bellow是我的代码snipet:
exports.genAdminCfg = function (app) {
let sql = 'SELECT * FROM nav_tree;';
let pool = require('mysql').createPool({
host: 'localhost',
user: 'root',
password: 'mysql',
database: 'n4_ctrl',
connectionLimit: 4,
multipleStatements: true
});
/* --- Works fine without "promisify":
pool.query(sql, function (err, rows) {
if (err) {
console.log(err);
return err;
} else {
app.locals.adminCfg = genCfg(rows);
app.locals.adminCfg.dbConnectionPool = pool;
}
});
*/
/* --- Does not worke with "promisify":
TypeError: Cannot read property 'connectionConfig' of undefined
at Pool.query (/usr/home/zipper/node/n4.live/node_modules/mysql/lib/Pool.js:194:33)
*/
require('util').promisify(pool.query)(sql).then(function (rows) {
app.locals.adminCfg = genCfg(rows);
app.locals.adminCfg.dbConnectionPool = pool;
}, function (error) {
console.log(error);
});
};
我评论的代码在没有promisify
的情况下工作正常。但是与promisify
相邻的类似代码不起作用并显示TypeError: Cannot read property 'connectionConfig' of undefined
。代码有什么问题?
node version = v8.1.4
回答如下:除非另有证明,否则始终应该预期方法依赖于上下文。
由于pool.query
是一种方法,它应该被绑定到正确的上下文:
const query = promisify(pool.query).bind(pool);
这可能是不必要的,因为大多数流行的图书馆都有基于承诺的替代方案,可以利用承诺,including mysql
。