为什么我不能用$app来调用function for Slim?

I am trying to make a reusable function, but everytime I try to use $app in the remote function, I get a blank screen. Here is what does work:

我正在尝试做一个可重用的函数，但是每次我尝试在远程函数中使用$app时，我都会得到一个空白的屏幕。以下是有效的方法:

$app = new \Slim\Slim();

//GET CHAPTERS
$app->get(
    '/chapters',
    function () use ($app) {
        $app->contentType('application/json');
        executeSql('SELECT * FROM chapters ORDER BY id');
    }
);

//GENERIC SQL EXECUTE
function executeSql($sql) {
    try {
        $db = getConnection();
        $stmt = $db->query($sql);  
        $results = $stmt->fetchAll(PDO::FETCH_OBJ);
        $db = null;
        echo json_encode($results);
    } catch(PDOException $e) {
        echo '{"error":{"text":'. $e->getMessage() .'}}'; 
    }
}

But I am trying to move the json header in the function and can't get this to work (gets the blank white screen):

但是我正在尝试在函数中移动json头，却无法让它工作(得到空白的白屏):

$app = new \Slim\Slim();

//GET CHAPTERS
$app->get(
    '/chapters',
    function () {
        executeSql('SELECT * FROM chapters ORDER BY id');
    }
);

//GENERIC SQL EXECUTE
function executeSql($sql) use ($app) {
        $app->contentType('application/json');
    try {
        $db = getConnection();
        $stmt = $db->query($sql);  
        $results = $stmt->fetchAll(PDO::FETCH_OBJ);
        $db = null;
        echo json_encode($results);
    } catch(PDOException $e) {
        echo '{"error":{"text":'. $e->getMessage() .'}}'; 
    }
}

Is something wrong with my syntax or how I'm using PHP? I also tried without the "use ($app)" at all but still same problem.

我的语法或PHP的使用有问题吗?我也试过不用“使用($app)”，但还是一样的问题。

4 个解决方案

#1

Easy way to fix this is to use getInstance();

解决这个问题的简单方法是使用getInstance();

function yourFunction(){
   $app = \Slim\Slim::getInstance();
}

#2

You could always pass the $app object as an argument to your function.

可以将$app对象作为参数传递给函数。

$app = new \Slim\Slim();

//GET CHAPTERS
$app->get(
    '/chapters',
    function () use ($app) {
        executeSql($app, 'SELECT * FROM chapters ORDER BY id');
    }
);

//GENERIC SQL EXECUTE
function executeSql(\Slim\Slim $app, $sql) {
        $app->contentType('application/json');
    try {
        $db = getConnection();
        $stmt = $db->query($sql);  
        $results = $stmt->fetchAll(PDO::FETCH_OBJ);
        $db = null;
        echo json_encode($results);
    } catch(PDOException $e) {
        echo '{"error":{"text":'. $e->getMessage() .'}}'; 
    }
}

#3

It is cleaner to keep database calls and app logic/presentation separate. I would return your "chapters" object immediately and handle anything else outside of the executeSql function.

将数据库调用和应用程序逻辑和表示分离开来会更清晰。我将立即返回您的“章节”对象，并处理executeSql函数之外的任何其他内容。

$app = new \Slim\Slim();

// GET CHAPTERS
$app->get('/chapters', function () use ($app) {

  $app->contentType('application/json');

  $chapters = executeSql('SELECT * FROM chapters ORDER BY id');

  if ($chapters) {
    $app->response->setStatus(200);
    echo json_encode($results);
  } else {
    $app->response->setStatus(400);
    echo '{"error":{"text":"error getting chapters"}}';
  }

});

// GENERIC SQL EXECUTE
function executeSql($sql) {
  try {
    $db = getConnection();
    $stmt = $db->query($sql);  
    $results = $stmt->fetchAll(PDO::FETCH_OBJ);
    $db = null;
    return $results;
  } catch(PDOException $e) {
    echo '{"error":{"text":'. $e->getMessage() .'}}'; 
  }
}

#4

the use keyword only applies to closure constructs, apart from the use with namespaces. so what your doing with a regular function is not supported. you will have to use global $app which is usually considered bad practice.

use关键字只适用于闭包构造，除了使用名称空间。所以你用常规函数做什么是不受支持的。你必须使用global $app，这通常被认为是不好的做法。

#1