如何在 Retrofit 中获取 JSON 数组？

Question

我有一个 JSON 数组，里面有 JSON Objects 这样的：

[
    {
        "id": "63",
        "userprofile": "userprofile.jpg",
        "username": "James",
        "content": "test.",
        "address": "1111 Parker St",
        "Post_date": "2022-05-25 02:41:15",
        "images": [
            "20220525_0241291.jpg",
            "20220525_0241290.jpg"
        ]
    }
]

我想将 images 数组中的字符串元素改为对象。谁能建议我如何制作这种 JSON？

[
    {
        "id": "63",
        "userprofile": "userprofile.jpg",
        "username": "James",
        "content": "test.",
        "address": "1111 Parker St",
        "Post_date": "2022-05-25 02:41:15",
        "images": [
            {"image": "20220525_0241291.jpg"},
            {"image": "20220525_0241290.jpg"}
         ]
    }
]

这是我的 PHP 代码

<?php

header("Content-Type:application/json");
include '../db_con.php'; 

$query = "SELECT Board.* , 
                GROUP_CONCAT(Board_images.imagepath separator ',') AS multiimages 
            FROM Board                       
                LEFT JOIN Board_images ON Board.index = Board_images.boardindex 
            GROUP BY Board.index 
            ORDER BY Board.index";  

$result = mysqli_query($conn, $query); 

$response = array();

while ($row = mysqli_fetch_assoc($result)) {

    array_push(
        $response,
        array(
            'id' => $row['index'], 
            'userprofile' => $row['userprofile'], 
            'username' => $row['username'], 
            'content' => $row['content'], 
            'address' => $row['address'], 
            'Post_date' => $row['Post_date'], 
            'images' => explode(',',$row['multiimages']) 
            
        )
    );
}

echo json_encode($response);
?>

Answer 1

explode returns 一个简单的字符串数组。您所要做的就是检查它并将每个字符串放入一个数组中。您可以循环执行此操作或使用 array function like array_map() 执行相同的操作，对每个项目应用回调。

您也不需要循环来填充您的响应数组，而是使用 mysqli_result::fetch_all(). You could use a loop to add the extra images element, but again I prefer using the array_walk() function 作为个人意见。

(array_map和array_walk的区别在于array_map returns根据回调returns生成的新数组。array_walk 仅修改现有数组。）

<?php
include '../db_con.php'; 

$query = "SELECT Board.* , GROUP_CONCAT(Board_images.imagepath separator ',') AS multiimages FROM Board                       
LEFT JOIN Board_images ON Board.index = Board_images.boardindex GROUP BY Board.index ORDER BY Board.index";  

$result = $con->query($query); 

// fetch all the records at once
$response = $result->fetch_all(\MYSQLI_ASSOC);

// this performs similar function to a foreach loop
array_walk(
    $response,
    function (&$v, $k) {
        // explode the comma-separated list into an indexed array
        $images = explode(",", $v["multiimages"]);
        // now turn it into a bunch of associative arrays
        $images = array_map(fn ($im) => ["image" => $im], $images);
        // and then add it to the original $response array
        $v["images"] = $images;
    }
);

header("Content-Type:application/json");
echo json_encode($response);

如何在 Retrofit 中获取 JSON 数组？

How to fetch JSON array in Retrofit?

php

json