錯誤：PDO類的對象無法轉換爲字符串

Question

我正在使用slim-framework v2和php來獲取json outputs.With這段代碼，我得到了關於該主題描述的錯誤。 MySQL表格格式不正確，現在無法更改，所以我以這種方式製作這些功能，因爲我不是很有經驗。 解決這個問題的最好方法是什麼？如果可以用sql命令完成，會更好，所以我可以從主循環中刪除這些函數嗎？循環中的函數是否壞？ ps：讓我知道如果主題看起來不對。

測試（）是客戶ID

function test($server, $user, $pass, $db) { 
    $result = array(); 
    $sql = "SELECT cid from tasks where total!=0"; 
    $db = newDB($server, $user, $pass, $db); 
    $stmt = $db->prepare($sql); 
    $stmt->execute(); 
    foreach ($stmt as $v) { 
    $result[] = ['cid'=> $v['cid'], 'test'=> toGet($server, $user, $pass, $db, $v['cid']), 'test2'=> toGet2($server, $user, $pass, $db, $v['cid'])]; 
    } 
    echo json_encode($result, JSON_FORCE_OBJECT); 
} 

和其他功能

function toGet($server, $user, $pass, $db, $id) { 
    $sql = "SELECT sum(`poso`) as posoe from `economics` where `custid`=:id and flag=0"; 
    $db = newDB($server, $user, $pass, $db); 
    $stmt = $db->prepare($sql); 
    $stmt->bindParam("id", $id); 
    $stmt->execute(); 
    $row = $stmt->fetch(PDO::FETCH_NUM); 
    return $row[0]; 
} 

function toGet2($server, $user, $pass, $db, $id) { 
    $sql = "SELECT sum(`poso`) as posoe from `economics` where `custid`=:id and flag=1"; 
    $db = newDB($server, $user, $pass, $db); 
    $stmt = $db->prepare($sql); 
    $stmt->bindParam("id", $id); 
    $stmt->execute(); 
    $row = $stmt->fetch(PDO::FETCH_NUM); 
    return $row[0]; 
} 

非常感謝你的主循環！

UPDATE： 打開調試$ APP->配置（ '調試'，真正的），終於得到了錯誤 類型：ErrorException 代碼：4096 消息：類PDO的對象無法轉換爲字符串 文件：/var/www/api/newdb.php 線：6

function newDB($host, $user, $pass, $db) { 
    $dbhost= $host; 
    $dbuser= $user; 
    $dbpass= $pass; 
    $dbname= $db; 
    $dbConnection = new PDO("mysql:host=$dbhost;dbname=$dbname", $dbuser, $dbpass); 
    $dbConnection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); 
    $dbConnection->query('set names utf8'); 
    return $dbConnection; 
} 

UPDATE2：修身的conf

include 'newdb.php'; 
require 'Slim/Slim.php'; 
\Slim\Slim::registerAutoloader(); 
$app = new \Slim\Slim(); 
$app->config('debug', true); 
$app->response->setStatus(200); 
$app->contentType('application/json; charset=utf-8'); 
$app->get('/test/:server/:user/:pass/:db', 'test'); 
$app->get('/', function() use($app) { 
    $app->response->setStatus(200); 
    echo "Welcome!"; 
}); 
$app->run(); 

Answer 1

該問題可以通過Freenode上的一個人的單個MYSQL查詢來解決。

- Reconnecting on db for each query was bad. 
- toGet() toGet2() removed 

我可以用單查詢

SELECT t1.custid as cid, sum(if(t2.flag=0,t2.poso,0)) as posoX, 
sum(if(t2.flag=1,t2.poso,0)) as posoY from tasks t1 
left join economics t2 on t2.custid=t1.custid and t2.flag in (0,1) group by t1.custid;