如何从硅石控制器接收JSON数据AJAX

Question

当我试图从AJAX一切PHP文件接收JSON数据正常工作：

test.php的

<?php 
header("Content-Type: application/json; charset=UTF-8"); 
$pdo = new PDO('mysql:host=localhost;dbname=database', 'root', ''); 
$stmt = $pdo->prepare("SELECT id, name FROM table"); 
$stmt->execute(); 
$stmt = $stmt->fetchAll(PDO::FETCH_CLASS); 

echo json_encode($stmt); 
?> 

main.js

var xmlhttp = new XMLHttpRequest(); 
xmlhttp.onreadystatechange = function() { 
    if (this.readyState == 4 && this.status == 200) { 
     myObj = JSON.parse(this.responseText); 
     console.log(myObj); 
     document.getElementById("par").innerHTML = myObj[4].id + " " + myObj[4].tag1; 
    } 
}; 
xmlhttp.open("GET", "http://localhost/project/app/models/Test.php", true); 
xmlhttp.send(); 

但是，当我试图从硅石控制器接收JSON：

Ajax.php

namespace AI\models; 
use Silex\Application; 
use Silex\Api\ControllerProviderInterface; 

class Ajax implements ControllerProviderInterface 
{ 
    public function connect(Application $app){ 
    $controllers = $app['controllers_factory']; 
    $controllers->get('/', 'AI\models\Ajax::home'); 
    return $controllers; 
    } 

    public function home(Application $app){ 
    header("Content-Type: application/json; charset=UTF-8"); 
    $result = $app['db']->prepare("SELECT id, name FROM table"); 
    $result->execute(); 
    $result = $result->fetchAll(\PDO::FETCH_CLASS, \AI\models\Ajax::class); 
    echo json_encode($result); 

    return $app['twig']->render('ajax.twig'); 
    } 

} 

main.js

var xmlhttp = new XMLHttpRequest(); 
xmlhttp.onreadystatechange = function() { 
    if (this.readyState == 4 && this.status == 200) { 
     myObj = JSON.parse(this.responseText); 
     console.log(myObj); 
     document.getElementById("par").innerHTML = myObj[4].id; 
    } 
}; 
xmlhttp.open("GET", "http://localhost/project/app/models/Ajax.php", true); 
xmlhttp.send(); 

我在控制台中的错误：

Uncaught SyntaxError: Unexpected token < in JSON at position 0 
    at JSON.parse (<anonymous>) 
    at XMLHttpRequest.xmlhttp.onreadystatechange (main.js:4) 
xmlhttp.onreadystatechange @ main.js:4 

我没有任何想法，为什么会出现，当我尝试接收JSON问题来自一堂课。

Answer 1

如果你要返回json，你应该使用JsonResponse Object。你也绝对不想像现在那样渲染一个模板，你只是想要json数据，为什么要渲染一个模板？

你可以按照以前链接的文档，但幸运Silex has a helper method for returning json data，你甚至都不需要使用JsonResponse（直接）：

<?php 

public function home(Application $app){ 

    $result = $app['db']->prepare("SELECT id, name FROM table"); 
    $result->execute(); 
    $result = $result->fetchAll(\PDO::FETCH_CLASS, \AI\models\Ajax::class); 

    return $app->json($result); 
}