编码一个完美的json

Question

我有这个代码

$md_query = "SELECT * FROM table ORDER BY id ASC";
$md_result = mysql_query($md_query, $con);

header('Cache-Control: no-cache, must-revalidate');
header('Content-type: application/json');

while($md_row=mysql_fetch_array($md_result))
    $data_row = array(
        'id' => $md_row['id'],
        'type' => $md_row['type'],
        'title' => $md_row['title'],
        'content' => $md_row['content'],
        'author' => $md_row['postedby'],
        'post_date' => $md_row['posteddate'],
        'publish' => $md_row['publish']
    );

print json_encode($data_row); `

但我只显示 1 条记录...有人如何解决这个问题？

Answer 1

您的 while 循环不包括 print 语句...因此，它循环遍历所有记录，每次完全重置 $data_row，然后在完成后打印一次。

要包含多个语句，您需要使用{ 和} 来封装块。

Answer 2

您正在循环您的数据并将$data_row 设置为每一行的新数组，但在退出循环之前您不会对其进行任何操作。

Answer 3

为什么显示所有行或用 {} 换行变得过于复杂？只需将$data_row 设为一个多维数组，json_encode() 就会使用 []：

while($md_row=mysql_fetch_array($md_result))
$data_row[] = array(   // please note I added [] !
    'id' => $md_row['id']
    ,'type' => $md_row['type']
);

print json_encode($data_row);

打印例如：

[{"id":"3","type":"One"},{"id":"8","type":"Two"},{"id":"9","type":"Three"},{"id":"10","type":"Four"}]

如果您将该 JSON 字符串转换回数组，则如下所示：

Array(
[0] => Array
    (
        [id] => 3
        [type] => One
    )

[1] => Array
    (
        [id] => 8
        [type] => Two
    )

[2] => Array
    (
        [id] => 9
        [type] => Three
    )

[3] => Array
    (
        [id] => 10
        [type] => Four
    ))

Answer 4

代码示例仅在循环完成后打印$data_row，此时$data_row 保存结果的最后一行。您需要将行收集到数据结构中，进行 JSON 编码并打印出来，或者在循环的每次迭代中打印每一行。

...
header('Cache-Control: no-cache, must-revalidate');
header('Content-type: application/json');

$md_query = $db->prepare(
    "SELECT id, type, title, content, postedby AS author, 
            posteddate AS post_date, publish
       FROM posts 
       ORDER BY id ASC");

try {
    $md_query->execute();
    echo json_encode($md_query->fetchAll(PDO::FETCH_ASSOC));
} catch (PDOException $exc) {
    ...
}

请注意，由于这会从表中获取所有行，因此可能会耗尽脚本的最大允许内存或运行时间。如果内存限制有问题，请更改负责显示结果的代码行，以便一次打印一个块。例如：

    ...
    $md_query->setFetchMode(PDO::FETCH_ASSOC);

    echo '[';
    $last = $md_query->rowCount()-1;
    foreach ($md_query as $i => $post) {
        echo json_encode($post);
        if ($i < $last) {
            echo ", ";
        }
    }
    echo ']';
} catch (PDOException $exc) {
    ...

Answer 5

您需要封装行记录，例如 {row1: {a:b, b:c}, row2:{e:f, g:h}}

$json = '{';
while($md_row=mysql_fetch_array($md_result)) {
$data_row = array(
    'id' => $md_row['id'],
    'type' => $md_row['type'],
    'title' => $md_row['title'],
    'content' => $md_row['content'],
    'author' => $md_row['postedby'],
    'post_date' => $md_row['posteddate'],
    'publish' => $md_row['publish']
);
$json .= '"' . $id . '" :' . json_encode($data_row) . ','; 
// $id just as an example for the string-value pair
}
$json = substr($json, 0, -1); // remove comma after last row
$json .= '}';
echo $json;

更多示例参见：

http://json.org/

http://json.org/example.html