php - 在 PHP 中从 Json 中提取关键元素

Question

我需要在 PHP 中使用 Json 文件，这样我就可以在其主要元素的特定键内进行迭代。

我有这个示例 Json 数据:

[{"A": [
    {
        "name": "object 1",
        "code": "x001",
        "date": "2018-01-01T23:00:00-0600"
    },
    {
        "name": "object 2",
        "code": "x002",
        "date": "2018-01-01T23:00:00-0600"
    },
    {
        "name": "object 3",
        "code": "x003",
        "date": "2018-01-01T23:00:00-0600"
    }
]},{"B": [
    {
        "name": "object 1",
        "code": "y001"
        "date": "2018-01-01T23:00:00-0600"
    },
    {
        "name": "object 2",
        "code": "y002",
        "date": "2018-01-01T23:00:00-0600"
    }
]}]

据我所知，我可以像这样处理 Json 文件(主键 A 和 B 中不包含嵌套元素):

<?php
$url = './data.json';
$data = file_get_contents($url);
echo "<!--- File contents -->\n";
var_dump($data);
$contents = json_decode($data, true);
echo "<!--- Associative Array -->\n";
var_dump($contents);


echo "<!--- BEGIN -->";
foreach ($contents as $element) {
        echo "Name: " . $element['name'] . "\n";
        echo "Code: " . $element['code'] . "\n";
        echo "Date: " . $element['date'] . "\n";
        echo "- - - - - -\n";
}
echo "<!--- END -->";
?>

我想做的是在给定键内调用循环，例如，对应于 B 的所有元素的循环:

    {
        "name": "object 1",
        "code": "y001"
        "date": "2018-01-01T23:00:00-0600"
    },
    {
        "name": "object 2",
        "code": "y002",
        "date": "2018-01-01T23:00:00-0600"
    }

它可以将这些元素提取到第二个关联数组或其他建议的方法......

预期结果应该是:

Name: object 1
Code: y001
Date: 2018-01-01T23:00:00-0600
- - - - - -
Name: object 2
Code: y002
Date: 2018-01-01T23:00:00-0600
- - - - - -

忽略A元素

Answer 1

此脚本可能会帮助您设计和输出所需的字符串。它适用于$element["B"]。您只需为数组的其他元素编写类似的 foreach 即可，例如 $element["A"]。

$url = './data.json';
$data = file_get_contents($url);
$output = "<!--- File contents -->\n";
$contents = json_decode($data, true);
$output .= "<!--- Associative Array -->\n";

$output .= "<!--- BEGIN -->\n";
foreach ($contents as $elements) {
    if (!$elements["B"]) {continue;} // You might remove this and add other elements of your inputs such as $elements["A"]
    foreach ($elements["B"] as $key => $element) {
        $output .= "Name: " . $element['name'] . "\n";
        $output .= "Code: " . $element['code'] . "\n";
        $output .= "Date: " . $element['date'] . "\n";
        $output .= "- - - - - -\n";
    }

}
$output .= "<!--- END -->\n";

echo $output;

您可能不需要逐行回显，可以将其存储在变量中，例如$output，并在末尾echo $output;。

输出:

<!--- File contents -->
<!--- Associative Array -->
<!--- BEGIN -->
Name: object 1
Code: y001
Date: 2018-01-01T23:00:00-0600
- - - - - -
Name: object 2
Code: y002
Date: 2018-01-01T23:00:00-0600
- - - - - -
<!--- END -->