PDO：执行数据库更新时，Json无法呈现响应

Question

I want to register the currently logged in username in a database field when he view a page. The database is a MySQL, and the language is PHP (XAMPP local server)

This is the code I'm using:

$ActiveUser = USER_NAME;
$id         = $rec_id;
$db->rawQuery("UPDATE postagens SET post_user_posted='$ActiveUser' WHERE 
post_id='$id'");

When I open the page via web browser the database is updated sucessfull. But although the database is updated correctly, the page returns the following error message:

!Error Processing Request.

At this point, the page should get the database information and display. But whenever the above error appears, the page does not load the information from the database. The page only displays the error message and the fields are blank.

I think something must be happening with json rendering. If I remove the UPDATE query code the error is not displayed and the database informations is correctly displayed. Also removing the code the json returns:

{"post_id":"1","post_title":"My first post.","post_text":"Lorem ipsum
dollor.","post_date":"2018-12-31
12:00:00","post_user_posted":"Welisson"}

When I run the update query the json does not give a return (or return empty)

The error log show this:

PHP Fatal error:  Uncaught PDOException: SQLSTATE[HY000]: General 
    error 
    in C:\xampp\htdocs\projetosimples\app\models\PDODb.php:680
    Stack trace:
    0 C:\xampp\htdocs\projetosimples\app\models\PDODb.php(680): 
    PDOStatement- 
    >fetchAll(2)
    1 C:\xampp\htdocs\projetosimples\app\models\PDODb.php(1611): PDODb- 
    >buildResult(Object(PDOStatement)) 2 C:\xampp\htdocs\projetosimples\app\controllers\PostagensController.php(93): PDODb->rawQuery('UPDATE postagen...')
    3 C:\xampp\htdocs\projetosimples\system\Router.php(227): PostagensController->view('1')
    4 C:\xampp\htdocs\projetosimples\system\Router.php(92): Router->run('postagens/view/...')
    5 C:\xampp\htdocs\projetosimples\index.php(84): Router->init()
    6 {main}
      thrown in C:\xampp\htdocs\projetosimples\app\models\PDODb.php on line 680

PDODb.php lines around 680:

/**
     * Return query result
     * 
     * @param PDOStatement $stmt
     * @return array
     */
    private function buildResult($stmt)
    {
        if ($this->useGenerator) {
            return $this->buildResultGenerator($stmt);
        } else {
            return $stmt->fetchAll($this->returnType); //THIS IS THE LINE 680
        }
    }

PDODb.php lines around 1611:

/**
     * Perform db query
     * 
     * @param string $query
     * @param array $params
     * @return array
     */
    public function rawQuery($query, $params = null)
    {
        $this->query = $query;
        if (is_array($params)) {
            $this->params = $params;
        }
        $stmt = $this->prepare();
        if ($stmt) {
            $stmt->execute();
            $this->lastError     = $stmt->errorInfo();
            $this->lastErrorCode = $stmt->errorCode();
            $result              = $this->buildResult($stmt); //LINE 1611
        } else {
            $result = null;
        }
        $this->reset();
        return $result;
    }

PostagensController.php line 93:

 function view( $rec_id = null , $value = null){
            $db = $this->GetModel();
            $fields = array( 'post_id',     'post_title',   'post_text',    'post_date',    'post_user_posted' );
            if( !empty($value) ){
                $db->where($rec_id, urldecode($value));
            }
            else{
                $db->where('post_id' , $rec_id);
            }
            $record = $db->getOne( 'postagens', $fields );
            if(!empty($record)){
                $ActiveUser = ucwords(USER_NAME);
    $id         = $rec_id;
                render_json($record); //THIS IS THE LINE 93
            }
            else{
                if($db->getLastError()){
                    render_error($db->getLastError());
                }
                else{
                    render_error("Registro não encontrado",404);
                }
            }
        }

Router.php line 227:

        // use the force layout when force layout is set
        $controller->view->force_layout = $this->force_layout;


        // Initialize Controller Class And Pass All Arguments to the Controller Action
        call_user_func_array(array($controller,$action),$args); //LINE 227
    }
    else{
        if($this->is_partial_view==true){
            echo "<div class='alert alert-danger'><b>$controller_name</b> Was  Not Found In Controller Directory. <b>Please Check </b>" . CONTROLLERS_DIR."</div>";
        }
        else{
            $this->page_not_found("<b>$controller_name</b> Was  Not Found In Controller Directory. <b>Please Check </b>" . CONTROLLERS_DIR);
        }
    }
}

Router line 92:

/**
     * Start page Dispatch From Current URl
     * @var string
     */
    function init(){

        $basepath = implode('/', array_slice(explode('/', $_SERVER['SCRIPT_NAME']), 0, -1)) . '/';

        // for now, we are only interested with the path only.
        $page_url  = substr($_SERVER['REQUEST_URI'], strlen($basepath)); 
        $path = parse_url( $page_url, PHP_URL_PATH );

        if(!empty( $path )){
            $this->run( $path ); //LINE 92
        }
        else{
            self::$page_name = DEFAULT_PAGE;
            self::$page_action = DEFAULT_PAGE_ACTION;

            $controller_name = ucfirst(DEFAULT_PAGE)."Controller";
            $controller = new IndexController;
            $controller->{DEFAULT_PAGE_ACTION}(); 
        }
    }

The complete view function:

/**
    * View Record Action 
    * @return View
    */
    function view( $rec_id = null , $value = null){
    $db = $this->GetModel();
    $fields = array( 'post_id',     'post_title',   'post_text',    'post_date',    'post_user_posted' );
        if( !empty($value) ){
            $db->where($rec_id, urldecode($value));
        }
        else{
            $db->where('post_id' , $rec_id);
        }
    $record = $db->getOne( 'postagens', $fields );
        if(!empty($record)){

        $ActiveUser = USER_NAME;
        $meu_id         = $rec_id;
        $db->rawQuery("UPDATE postagens SET post_user_posted='$ActiveUser' WHERE post_id='$meu_id'"); //MY UPDATE QUERY
        render_json($records); //THE RENDER ONLY RETURN DATA IF I REMOVE THE UPDATE QUERY
        }
        else{
            if($db->getLastError()){
                render_error($db->getLastError());
            }
            else{
                render_error("Registro não encontrado",404);
            }
        }
        }    

Does anyone know why json is not properly rendering?

Answer 1

Try with this (note the curly brackets):

$db->rawQuery("UPDATE `postagens` SET post_user_posted='{$ActiveUser}' WHERE post_id='{$meu_id}'");

Or use PDO prepared statements which are more readable.

In general, if you want to know what's wrong with your queries, you can embed them in try/catch blocks, and see what's the caught exception. So something like:

try {
    $db->rawQuery("UPDATE postagens SET post_user_posted='{$ActiveUser}' WHERE post_id='{$meu_id}'");
    render_json($records);
} catch(\Exception $e) {
   // this is the error:
   // $e->getMessage();
}

---

On an unrelated note, you are mixing different naming conventions for your variables which is a bad practice!