[英]How to return value from a series of cascading async code
I need some advice on how to re/write the db specific cascading code (callback) so that I can effectively return a value to the underlying if/else. 我需要一些有关如何重新/编写特定于数据库的级联代码(回调)的建议,以便可以有效地将值返回给基础的if / else。
I am using restify and the db lib is node-mssql (tedious). 我正在使用restify,数据库库为node-mssql(乏味)。
function authenticate(req, res, next) {
var auth = req.authorization;
var err;
if (auth.scheme !== 'Basic' || ! auth.basic.username || ! auth.basic.password) {
authFail(res);
err = false;
} else {
var sql = "SELECT ..."
var connection = new mssql.Connection(config.mssql, function(err) {
if (err) {console.log(err);}
var request = connection.request();
request.query(sql, function(err, recordset) {
if (err) {console.log(err);}
if (recordset.length === 0) {
authFail(res);
err = false; // <--- I need to be able to return this
} else {
authSuccess();
}
});
});
}
next(err);
}
I've reviewed the suggested duplicate, and while I think, I understand the issue, I can't work out the cleanest (lets be honest any) way to get this to work. 我已经审查了建议的重复项,尽管我认为我理解这个问题,但是我无法找到最干净的方法(老实说)使它生效。
How about using Promise
s? 使用Promise
怎么样?
function authenticate(req, res, next) {
var auth = req.authorization;
if (auth.scheme !== 'Basic' || ! auth.basic.username || ! auth.basic.password) {
authFail(res);
next(false);
} else {
var sql = "SELECT ..."
var connection = new mssql.Connection(config.mssql, function(err) {
if (err) {console.log(err);}
var request = connection.request();
request.query(sql).then(function(recordset) {
if (recordset.length === 0) {
authFail(res);
return false; // <--- return this
} else {
authSuccess();
}
}).catch(function(err) {
console.log(err);
return err;
}).then(function(err) { next(err); });
});
}
}
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