Php 从用foreach循环构造的JSON中删除最后一个逗号

我有一个构建JSON的脚本：

echo "{";
echo "\"name\": \"flare\","."\n";
echo "\"children\": ["."\n";
foreach($tree as $tag => $customer){
    foreach($customer as $customerId => $order){
        echo "{\"name\":\"".$customerId."\",";
        echo "\"children\": ["."\n";
            foreach($order as $orderId => $orderTotal){
                echo "{\"name\": \"".$orderId."\", \"size\": \"".$orderTotal."\"},";
            }
        echo "]";
        echo "},";
    }
}
echo "]";
echo "}";

$Tree、$customer和$order是多维数组的级别，用于重复循环以查找数组的特定“$order”级别。生成的JSON包含以下JSON：

{
"name":"flare",
"children":[
    {
    "name":"4",
    "children":[
    {
        "name":"17",
        "size":"104.15"
        },
        {
        "name":"18",
        "size":"104.15"
        },
        {
        "name":"23",
        "size":"104.15"
        },
        {
        "name":"25",
        "size":"104.15"
        }, // Remove this comma
    ]
    },
    {
    "name":"12",
    "children":[
        {
        "name":"36",
        "size":"280.00"
        },
        {
        "name":"37",
        "size":"384.15"
        },
        {
        "name":"38",
        "size":"664.15"
        },
        {
        "name":"43",
        "size":"112.00"
        },
        {
        "name":"278",
        "size":"235.20"
        },
        {
        "name":"281",
        "size":"117.60"
        },
        {
        "name":"298",
        "size":"117.60"
        }, // Remove this comma
    ]
    },
    {
    "name":"16",
    "children":[
        {
        "name":"60",
        "size":"112.00"
        }, // Remove this comma
    ]
    },
    {
    "name":"17",
    "children":[
        {
        "name":"236",
        "size":"235.20"
        },
        {
        "name":"295",
        "size":"117.60"
        },
    ]
    }, // Revome this comma
]
}

一切正常，但我必须删除最后一个逗号，因为它在解析JSON时产生错误。我不能使用substr（）和rtrim（），因为它们删除了JSON中的所有逗号，而不是最后一个

问候

已更新

---

现在我有两个级别的逗号要删除。

正如有人所说，不要试图手动构建JSON字符串，用php构建数据结构并使用：

---

不要通过混合字符串来构建JSON！构建一个合适的PHP数据结构，然后将其推进

json\u encode

。认真地说：使用

json\u encode（）

。当语言为您提供简单的函数调用时，不要尝试从头开始创建序列化数据格式。从PHP5.4开始，根据选择的答案：

$json\u string=json\u encode（$data，json\u PRETTY\u PRINT）
$data = array("name" => "flare", "children" => array());
foreach($tree as $tag => $customer){
    foreach($customer as $customerId => $order){
        $_data = array("name" => $customerId, "children" => array());
        foreach($order as $orderId => $orderTotal){
              $_data["children"][] = array("name" => $orderId, "size" => $orderTotal);
        }
        $data["children"][] = $_data;
    }
}
echo json_encode($data, JSON_PRETTY_PRINT);