PHP - JSON编码的问题

我目前正在开发一个Android应用程序作为我学校项目的一部分。我需要设置一个API，它将从数据库中检索所有讲座，并将它们输出为JSON。这里有一个例子，我多么希望他们输出：

{ 
    "count: 4, 
    "msg": "", 
    "user_id": 1, 
    "name": "John Doe" 

    "lectures": [{ 
     "id": 1, 
      "starting_at": "2015-11-30 13:00", 
      "ending_at": "2015-11-30 15:00", 
      "course_name": "Name of Course #1", 
    }, { 
     "id": 2, 
      "starting_at": "2015-11-30 13:00", 
      "ending_at": "2015-11-30 15:00", 
      "course_name": "Name of Course #2", 
    }, { 
     "id": 3, 
      "starting_at": "2015-11-30 13:00", 
      "ending_at": "2015-11-30 15:00", 
      "course_name": "Name of Course #3", 
    }] 
}

但是，相反，它重复检索到的所有对象和我的输出是这样的：

{ 
    "count":4, 
    "msg":"", 

    "lectures":[{ 
     "id":"1", 
     "0":"1", // Duplicated object 
     "starting_at": "2015-11-30 13:00:00", 
     "1":"2015-11-30 13:00:00", // Duplicated object 
     "ending_at":"2015-11-30 15:00:00", 
     "2":"2015-11-30 15:00:00", // Duplicated object 
     "user_id":"1", 
     "3":"1", // Duplicate object 
     "course":"Course Name #1", 
     "4":"Course Name #1", // Duplicated object 
     "user_name":"John Doe", 
     "5":"John Doe" 
    }, { 
     "id":"2", 
     "0":"2", // Duplicated object 
     "starting_at": "2015-11-30 13:00:00", 
     "1":"2015-11-30 13:00:00", // Duplicated object 
     "ending_at":"2015-11-30 15:00:00", 
     "2":"2015-11-30 15:00:00", // Duplicated object 
     "user_id":"1", 
     "3":"1", // Duplicated object 
     "course": "Course Name #2", 
     "4":"Course Name #2", // Duplicated object 
     "user_name":"John Doe", 
     "5":"John Doe" // Duplicated object 
    ]} 
}

我不得不承认，我对于JSON来说相对来说比较新，而且肯定需要一些帮助。这里是我的API调用PHP：

<?php 
require_once("dbconnect.php"); 
$user_id = 1; 

// Prepare the statement 
$stmt = $pdo->prepare(" 
SELECT 
lectures.id, 
lectures.starting_at, 
lectures.ending_at, 
users_lectures.user_id, 
courses.name AS course, 
users.name AS user_name 
FROM lectures 
LEFT JOIN courses ON courses.id = lectures.course_id 
LEFT JOIN users_lectures ON users_lectures.lecture_id = lectures.id 
LEFT JOIN users ON users.id = users_lectures.user_id 
WHERE users_lectures.user_id = :user_id 
AND lectures.starting_at >= CURRENT_DATE() 
ORDER BY lectures.starting_at DESC"); 

$stmt->execute(array(':user_id' => $user_id)); 
if($stmt->rowCount() > 0) { 
    $lectures = array(); 

    while ($row = $stmt->fetch()) {  
     $lectures[] = $row; 

    } 

    echo json_encode(["count" => count($lectures), "msg" => "", "user_id" => $row['user_id'], "name" => $row['user_name'], "lectures" => [$lectures]]); 
} else { 
    echo json_encode(["count" => 0, "msg" => "No lectures today"]); 
}

来源

2015-11-30 B_CooperA

这些都不是重复的，他们是由于PDO's FETCH_MODE。它默认获取数字键和关联键。

使用

$stmt->fetch(PDO::FETCH_NUM)

的数字和

$stmt->fetch(PDO::FETCH_ASSOC)

为联想

来源

2015-11-30 05:14:35 Thamilan

PHP - JSON编码的问题

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