Question

我开始学习json并开发一个测验应用程序，它从php页面获取json以将其显示为html。我用php从mysql表中选择数据并将其打印为json。

<?php
    header('Access-Control-Allow-Origin: *');
    header("Cache-Control: no-cache");
    header('Content-Type: application/json');
    include("dbcon.php");
    $sql = "SELECT * FROM quiz;";
    $result = $conn->query($sql);
    if ($result->num_rows > 0) {
        // output data of each row
        while($row = $result->fetch_assoc()) {
            echo json_encode($row, JSON_PRETTY_PRINT)."\r\n";
        }
    } 
    else {
        echo "nodata";
    }
$conn->close();
?>

结果是：

{
"id": "1",
"question": "ques1?",
"opt1": "Microsoft",
"opt2": "W3C",
"opt3": "Google",
"opt4": "IBM",
"answer": "W3C"
}
{
"id": "2",
"question": "ques2?",
"opt1": "Yahoo",
"opt2": "Google",
"opt3": "Bing",
"opt4": "DuckDuckGo",
"answer": "Google"
}

这段代码完美无缺，打印json。但是如何打印相同的键值作为数组，所以输出就像 -

{
    "id":[ "1", "2" ],
    "question":[ "ques1?", "ques2?" ],
    "opt1":[ "asd", "fgh" ],
    "opt2":[ "qwe", "rty" ],
    "opt3":[ "qwer", "vbbn" ],
    "opt4":[ "asdfg", "ascvb" ],
    "answer":[ "asd", "fgh" ],
}

我相信我期望的结果会让使用javascript从中读取数据很简单： -

var q1 = myObj.question[0];

我看到许多问题都有相同的标题，但它们都是不同的情况。如果我错了，请提供解决方案并纠正我的愚蠢。

Answer 1

要获得有效的JSON，您需要执行以下操作：

header('Access-Control-Allow-Origin: *');
header("Cache-Control: no-cache");
header('Content-Type: application/json');
include("dbcon.php");
$sql = "SELECT * FROM quiz;";
$result = $conn->query($sql);
$theResultIWant = [];
if ($result->num_rows > 0) {        
    while($row = $result->fetch_assoc()) {
        $theResultIWant[] = $row;
    }
} 
else {
    echo "nodata";
}
$conn->close();
echo json_encode($theResultIWant, JSON_PRETTY_PRINT);
//That is all

要获得您想要的结果：

header('Access-Control-Allow-Origin: *');
header("Cache-Control: no-cache");
header('Content-Type: application/json');
include("dbcon.php");
$sql = "SELECT * FROM quiz;";
$result = $conn->query($sql);
$theResultIWant = [];
if ($result->num_rows > 0) {        
    while($row = $result->fetch_assoc()) {
        foreach ($row as $key=>$value) {
             $theResultIWant[$key] = $theResultIWant[$key]??[]; //or isset($theResultIWant[$key])?$theResultIWant[$key]:[]; in PHP < 7
             $theResultIWant[$key][] = $value;
        } 
    }
} 
else {
    echo "nodata";
}
$conn->close();
echo json_encode($theResultIWant, JSON_PRETTY_PRINT);

任何一种方法都可以合理地阅读JavaScript，但第二种方法在大小方面被认为更紧凑（但是如果你对结果进行GZipping，第一种方法可以被压缩得更多）。

Answer 2

在while循环之前为对象定义一个数组，例如

$json=array();

在while循环中执行以下操作

$json['object-key'][]=$row['key'];

示例

$json['id'][]=$row['id'];

while循环之后使用json_encode（）将$ json数组转换为json对象;功能

Answer 3

        <?php
        header('Access-Control-Allow-Origin: *');
        header("Cache-Control: no-cache");
        header('Content-Type: application/json');
        include("dbcon.php");
        $sql = "SELECT * FROM quiz;";
        $result = $conn->query($sql);
        $dataArr = [];
        if ($result->num_rows > 0) {
            // output data of each row
            while($row = $result->fetch_assoc()) {                

                   $dataArr['id'][] = $row['id'];

                   $dataArr['question'][] = $row['question'];

                   $dataArr['opt1'][] = $row['opt1'];

                   $dataArr['opt2'][] = $row['opt2'];

                   $dataArr['opt3'][] = $row['opt3'];

                   $dataArr['opt4'][] = $row['opt4'];

                   $dataArr['answer'][] = $row['answer'];

            }
        } 
        else {
            echo "nodata";
        }
    $conn->close();
    ?>
echo json_encode($dataArr, JSON_PRETTY_PRINT);

您可以按照我上面的编码使用。

php json_encode与数组相同的密钥

3 个答案: