Question

我有一個好奇的問題。

我從數據庫中提取行並將其插入數組。但Array.push()將無法​​正常工作。

來源

var donations_data = []; 

/* Get Donations */ 
instance.server.db.query("SELECT * FROM `donations` WHERE `userid`='" + instance.user_data.userid + "' AND `visible`='1' ORDER BY `date` DESC LIMIT 10", function(error, rows, fields) { 
    if(rows.length > 0) { 
     _.each(rows, function (entry, index) { 
      console.log(">>>>>>>>>>>>>>>>>>>>>"); 
      console.log(entry); 
      console.log(">>>>>>>>>>>>>>>>>>>>>"); 

      donations_data.push({ 
       username:   entry.from_username, 
       note:    entry.note, 
       timestamp:   entry.date, 
       amount:    entry.amount, 
       currency:   entry.currency, 
       currency_symbol: '?', 
       transaction_id:  entry.transaction_id, 
       paypal_email:  entry.from_paypal_email 
      }); 
     }); 
    } 
}); 

console.log("=================================="); 
console.log(donations_data); 
console.log("=================================="); 

輸出

>>>>>>>>>>>>>>>>>>>>> 
{ id: 4, 
    userid: 1, 
    from_username: 'user 2', 
    from_paypal_email: 'demo@example.com', 
    transaction_id: '12345', 
    status: 'COMPLETED', 
    note: 'No Message', 
    date: 1386012587, 
    amount: '5.00', 
    cent_amount: 0, 
    an_dt: '', 
    currency: 'EUR', 
    visible: 1, 
    date2: Mon Dec 02 2013 20:29:47 GMT+0100 (CET), 
    new: 0 } 
>>>>>>>>>>>>>>>>>>>>> 
>>>>>>>>>>>>>>>>>>>>> 
{ id: 3, 
    userid: 1, 
    from_username: 'USer 1', 
    from_paypal_email: 'demo@example.com', 
    transaction_id: '23ewqs', 
    status: 'COMPLETED', 
    note: 'Das ist ein Test', 
    date: 1386012427, 
    amount: '5.00', 
    cent_amount: 0, 
    an_dt: '', 
    currency: 'EUR', 
    visible: 1, 
    date2: Mon Dec 02 2013 20:27:07 GMT+0100 (CET), 
    new: 0 } 
>>>>>>>>>>>>>>>>>>>>> 
================================== 
[] 
================================== 

你能告訴我爲什麼陣列就不會成交？數據將打印出來，因此必須工作...

Answer 1

您正在嘗試記錄在異步instance.server.db.query方法有機會完成之前將對象添加到數組的結果。一旦循環完成，使用回調獲取數據

var donations_data = []; 

function doQuery(callback) { 
    instance.server.db.query(SQL, function(error, rows, fields) { 
    // add data to array with loop 
    // call callback 
    callback(donations_data); 
    }); 
} 

doQuery(function (donations_data) { 
    console.log(donations_data); 
});