blocks|key|4344864|text|下面的示例应该适用于您：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4344865|​|4344866|async+()+=>+{
++const+connection+=+await+(util.promisify(pool.getConnection).bind(pool))();

++const+fn2+=+util.promisify(connection.query).bind(connection);
++const+rows+=+await+fn2('SELECT+col1,+col2+FROM+Users+WHERE+email+=+?',+[email]);

++connection.release();

++return+rows;
}|code-block|syntax|javascript|4344867|4344868|此示例使用Node.js的标准MySQL模块。util.promisify是Node.js的内置实用程序。使用节点8。|4344869|代码被包装到一个异步函数中。在它的第一行中，回调函数‘pool.getConnection’被转换为promises，并通过附加的‘await’语句立即调用。这将创建一个异步函数序列，并返回一个值(一个连接)，而不是一个函数或承诺。下一行对‘conection.query’执行相同的操作，但为了简单起见将代码拆分为两个语句。最后，该函数像任何同步函数一样返回查询结果。|4344870|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Q|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|R|8|@]|9|@]|A|$G|H]]|$1|I|3|C|5|6|7|S|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|T|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|U|8|@]|9|@]|A|$]]|$1|N|3|-4|5|6|7|V|8|@]|9|@]|A|$]]]|O|$]]

<p>The following example should work for you:</p>

<p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-html lang-html prettyprint-override"><code>async () =&gt; {
  const connection = await (util.promisify(pool.getConnection).bind(pool))();

  const fn2 = util.promisify(connection.query).bind(connection);
  const rows = await fn2('SELECT col1, col2 FROM Users WHERE email = ?', [email]);

  connection.release();

  return rows;
}</code></pre>
</div>
</div>
</p>

<p>This example uses the standard MySQL module for Node.js. And the util.promisify is the built-in utility of Node.js. Node 8 is used.</p>

<p>The code is wrapped into an async function. Within it on the first line the callback function ‘pool.getConnection’ is converted into promises and called instantly with the additional ‘await’ statement. This creates a sequence of the async function and returns a value (a connection) instead of a function or promises. The next line does the same for the ‘conection.query’, but splits the code into two statements for the sake of simplicity. Finally the function returns the result of the query like any synchronous function.</p>


blocks|key|4345137|text|下面是promisify的一个实现：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4345138|​|4345139|var+promisify+=+function(fn)+{
++return+function(){
++++var+args+=+[].slice.apply(arguments);
++++return+new+Promise(
++++++function(resolve,reject){
++++++++fn.apply(
++++++++++null,
++++++++++args.concat([
++++++++++++function(){
++++++++++++++var+results+=+[].slice.apply(arguments);
++++++++++++++(results[0])//first+argument+of+callback+is+error
++++++++++++++++?+reject(results[0])//reject+with+error
++++++++++++++++:+resolve(results.slice(1,results.length))//resolve+with+result(s)
++++++++++++}
++++++++++])
++++++++)
++++++}
++++);
++}
};

//some+object+that+has+async+functions+using+callbacks+
//+and+using+'this'+as+invoking+object
var+callbackApi+=+{
++name:"callback+api",
++age:22,
++asyncFunction:function(arg1,arg2,callback){
++++setTimeout(
++++++function(){callback(null,arg1,arg2,this.name,this.age);}.bind(this),
++++++10
++++)
++}
}

//my+object+that+will+use+the+api+functions+with+promisify
//++and+using+'this'+as+invoking+object
var+myObject+=+{
++connection:"connection",
++doSomething:function(arg){
++++var+asyncFnAsPromise+=+
++++++//make+sure+to+bind+asyncFunction+to+callbackApi
++++++promisify(callbackApi.asyncFunction.bind(callbackApi));
++++//return+promise+created+with+result+promisified+callback+api
++++return+asyncFnAsPromise(this.connection,arg)
++}
}

myObject.doSomething(44)
.then(
++resolve=>console.log("resolve:",resolve)
);|code-block|syntax|javascript|4345140|4345141|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|M|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|N|8|@]|9|@]|A|$G|H]]|$1|I|3|C|5|6|7|O|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|P|8|@]|9|@]|A|$]]]|K|$]]

<p>Here is an implementation of promisify:</p>

<p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>var promisify = function(fn) {
  return function(){
    var args = [].slice.apply(arguments);
    return new Promise(
      function(resolve,reject){
        fn.apply(
          null,
          args.concat([
            function(){
              var results = [].slice.apply(arguments);
              (results[0])//first argument of callback is error
                ? reject(results[0])//reject with error
                : resolve(results.slice(1,results.length))//resolve with result(s)
            }
          ])
        )
      }
    );
  }
};

//some object that has async functions using callbacks 
// and using 'this' as invoking object
var callbackApi = {
  name:"callback api",
  age:22,
  asyncFunction:function(arg1,arg2,callback){
    setTimeout(
      function(){callback(null,arg1,arg2,this.name,this.age);}.bind(this),
      10
    )
  }
}

//my object that will use the api functions with promisify
//  and using 'this' as invoking object
var myObject = {
  connection:"connection",
  doSomething:function(arg){
    var asyncFnAsPromise = 
      //make sure to bind asyncFunction to callbackApi
      promisify(callbackApi.asyncFunction.bind(callbackApi));
    //return promise created with result promisified callback api
    return asyncFnAsPromise(this.connection,arg)
  }
}

myObject.doSomething(44)
.then(
  resolve=&gt;console.log("resolve:",resolve)
);</code></pre>
</div>
</div>
</p>


blocks|key|4344916|text|如果你愿意，你可以自己承诺：const+promisify+=+f+=>+(...args)+=>+new+Promise((a,b)=>f(...args,+(err,+res)+=>+err+?+b(err)+:+a(res)));|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4344917|entityMap^0|E|2W|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

<p>You can promise it by yourself if you want:
<code>const promisify = f =&gt; (...args) =&gt; new Promise((a,b)=&gt;f(...args, (err, res) =&gt; err ? b(err) : a(res)));</code></p>


blocks|key|4344964|text|Util是从Node8.x开始包含的，所以如果你可以更新Node，我会这么做的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4344965|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

<p>Util is included from Node 8.x on so if you can update node I'd do that.</p>


blocks|key|4344977|text|分享我的工作示例：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4344978|我使用这个Promisified+MySQL+middleware+for+Node.js|offset|length|4344979|这是我的database.js|4344980|var+mysql+=+require('mysql');+

//+node+-v+must+>+8.x+
var+util+=+require('util');


//++!!!!!+for+node+version+<+8.x+only++!!!!!
//+npm+install+util.promisify
//require('util.promisify').shim();
//+-v+<+8.x++has+problem+with+async+await+so+upgrade+-v+to+v9.6.1+for+this+to+work.+



//+connection+pool+https://github.com/mysqljs/mysql+++[1]
var+pool+=+mysql.createPool({
++connectionLimit+:+process.env.mysql_connection_pool_Limit,+//+default:10
++host+++++:+process.env.mysql_host,
++user+++++:+process.env.mysql_user,
++password+:+process.env.mysql_password,
++database+:+process.env.mysql_database
})


//+Ping+database+to+check+for+common+exception+errors.
pool.getConnection((err,+connection)+=>+{
if+(err)+{
++++if+(err.code+===+'PROTOCOL_CONNECTION_LOST')+{
++++++++console.error('Database+connection+was+closed.')
++++}
++++if+(err.code+===+'ER_CON_COUNT_ERROR')+{
++++++++console.error('Database+has+too+many+connections.')
++++}
++++if+(err.code+===+'ECONNREFUSED')+{
++++++++console.error('Database+connection+was+refused.')
++++}
}

if+(connection)+connection.release()

+return
+})

//+Promisify+for+Node.js+async/await.
+pool.query+=+util.promisify(pool.query)



+module.exports+=+pool|code-block|syntax|javascript|4344981|您必须升级节点-v+>+8.x|4344982|必须使用async函数才能使用await。|4344983|示例：|4344984|+++var+pool+=+require('./database')

++//+node+-v+must+>+8.x,+-->+async+/+await++
++router.get('/:template',+async+function(req,+res,+next)+
++{
++++++...
++++try+{
+++++++++var+_sql_rest_url+=+'SELECT+*+FROM+arcgis_viewer.rest_url+WHERE+id='%2B+_url_id;
+++++++++var+rows+=+await+pool.query(_sql_rest_url)

+++++++++_url++=+rows[0].rest_url+//+first+record,+property+name+is+'rest_url'
+++++++++if+(_center_lat+++==+null)+{_center_lat+=+rows[0].center_lat++}
+++++++++if+(_center_long++==+null)+{_center_long=+rows[0].center_long+}
+++++++++if+(_center_zoom++==+null)+{_center_zoom=+rows[0].center_zoom+}++++++++++
+++++++++_place+=+rows[0].place


+++++++}+catch(err)+{
++++++++++++++++++++++++throw+new+Error(err)
+++++++}|4344985|entityMap|0|LINK|mutability|MUTABLE|url|https://gist.github.com/matthagemann/30cfee724d047007a031eb12b3a95a23^0|0|5|14|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|13|8|@]|9|@$D|14|E|15|1|16]]|A|$]]|$1|F|3|G|5|6|7|17|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|18|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|19|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|1A|8|@]|9|@]|A|$]]|$1|Q|3|R|5|6|7|1B|8|@]|9|@]|A|$]]|$1|S|3|T|5|J|7|1C|8|@]|9|@]|A|$K|L]]|$1|U|3|-4|5|6|7|1D|8|@]|9|@]|A|$]]]|V|$W|$5|X|Y|Z|A|$10|11]]]]

<p>Share my working example:</p>

<p>I use this <a href="https://gist.github.com/matthagemann/30cfee724d047007a031eb12b3a95a23" rel="nofollow noreferrer">Promisified MySQL middleware for Node.js</a></p>

<p>here is my database.js</p>

<pre><code>var mysql = require('mysql'); 

// node -v must &gt; 8.x 
var util = require('util');


//  !!!!! for node version &lt; 8.x only  !!!!!
// npm install util.promisify
//require('util.promisify').shim();
// -v &lt; 8.x  has problem with async await so upgrade -v to v9.6.1 for this to work. 



// connection pool https://github.com/mysqljs/mysql   [1]
var pool = mysql.createPool({
  connectionLimit : process.env.mysql_connection_pool_Limit, // default:10
  host     : process.env.mysql_host,
  user     : process.env.mysql_user,
  password : process.env.mysql_password,
  database : process.env.mysql_database
})


// Ping database to check for common exception errors.
pool.getConnection((err, connection) =&gt; {
if (err) {
    if (err.code === 'PROTOCOL_CONNECTION_LOST') {
        console.error('Database connection was closed.')
    }
    if (err.code === 'ER_CON_COUNT_ERROR') {
        console.error('Database has too many connections.')
    }
    if (err.code === 'ECONNREFUSED') {
        console.error('Database connection was refused.')
    }
}

if (connection) connection.release()

 return
 })

// Promisify for Node.js async/await.
 pool.query = util.promisify(pool.query)



 module.exports = pool
</code></pre>

<p>You must upgrade node -v > 8.x </p>

<p>you must use async function to be able to use await.</p>

<p>example:</p>

<pre><code>   var pool = require('./database')

  // node -v must &gt; 8.x, --&gt; async / await  
  router.get('/:template', async function(req, res, next) 
  {
      ...
    try {
         var _sql_rest_url = 'SELECT * FROM arcgis_viewer.rest_url WHERE id='+ _url_id;
         var rows = await pool.query(_sql_rest_url)

         _url  = rows[0].rest_url // first record, property name is 'rest_url'
         if (_center_lat   == null) {_center_lat = rows[0].center_lat  }
         if (_center_long  == null) {_center_long= rows[0].center_long }
         if (_center_zoom  == null) {_center_zoom= rows[0].center_zoom }          
         _place = rows[0].place


       } catch(err) {
                        throw new Error(err)
       }
</code></pre>


<p>I'm trying to promisify a mysql function but when I run it the console shows this error <code>util.Promisify is not a function</code>. This is my code:</p>

<p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>var util=			require('util');
var mysql=          require('mysql');

var conection=mysql.createConnection({           
				host:'localhost',                   
				user:'root',                        
				password:'616897',               
				database:'proyect'                    
	});
  
  var query = util.promisify(conection.query);
  
  query(data.valida_user).then((rows)=&gt;{
	console.log(rows);
}).catch((error)=&gt;{
	console.log(error);
})</code></pre>
</div>
</div>
</p>

<p>The same error if 
<code>var query = util.promisify(mysql.query);</code></p>

<p>I´m new programming but I'm trying to learn.</p>


NodeJs util.promisify is not a function

MySQL

我正在尝试简化一个mysql函数，但是当我运行它时，控制台显示这个错误util.Promisify is not a function。这是我的代码：​var util=require('util');var mysql=          require('mysql');var conection=mysql.cr...

问NodeJs util.promisify不是函数
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