如何在 PHP 中访问并返回 foreach 的特定值

Question

所以我有一个如下所示的请求响应

$json='[ {"item_cat":"Stationary","items":[{"item_name":"A4 Paper","qty":"2"},{"item_name":"Test Paper","qty":"6"}],"total":"2"},

{"item_cat":"Computer Accessory ","items":[{"item_name":"Power pack","qty":"2"}],"total":"1"},

{"item_cat":"Material","items":[{"item_name":"T-Shirt","qty":"3"},

{"item_name":"Cap","qty":"5"}],"total":"2"}]';

我正在尝试获取每个 item_name 和 qty，以便我可以使用它们来操作我的数据库。这是我所做的

$data = json_decode($json, true);

$len = count($data);

    for($i =0; $i< $len; $i++){

            $item_length = count($data[$i]['items']);

        for($c=0; $c < $item_length; $c++){

            foreach ($data[$i]['items'][$c] as $key => $value ) {

                $qty = '';

                if($key == "qty"){

                    $qty = $data[$i]['items'][$c];

                    }

                if($key == 'item_name'){

                    $item_name = "$value";

                    }

                    $sql= $db->query("SELECT `stock` from `inventory` WHERE `item_name` = '$item_name'");

                    while ($sql1 = $sql->fetch_assoc()) {

                            $stock = $sql1['stock'];

                  }

                    if($stock > $qty ){

                        $stock_balance = $stock - $qty;

                    $quantity = (int)$qty;

                         $db->query("UPDATE `inventory` SET `stock` =  (`stock` - '$quantity')   WHERE `item_name` = '$item_name'");

                    }else{

                        echo "<h3> This Operation Not Allowed: Stock Balance Is Less Than The Request <h3>";

                    }

                }

            }

        }

遇到非数字值，这是 $qty 的结果，因为我无法仅返回 qty 值。我尝试过其他几种方法。我真的很累了。如果有任何帮助，我将不胜感激。干杯!

Answer 1

让我们分解你的代码。这是json：[&nbsp; &nbsp;{&nbsp; &nbsp; &nbsp; "item_cat":"Stationary",&nbsp; &nbsp; &nbsp; "items":[&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;{&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "item_name":"A4 Paper",&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "qty":"2"&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;},&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;{&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "item_name":"Test Paper",&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "qty":"6"&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;}&nbsp; &nbsp; &nbsp; ],&nbsp; &nbsp; &nbsp; "total":"2"&nbsp; &nbsp;},&nbsp; &nbsp;{&nbsp; &nbsp; &nbsp; "item_cat":"Computer Accessory ",&nbsp; &nbsp; &nbsp; "items":[&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;{&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "item_name":"Power pack",&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "qty":"2"&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;}&nbsp; &nbsp; &nbsp; ],&nbsp; &nbsp; &nbsp; "total":"1"&nbsp; &nbsp;},&nbsp; &nbsp;{&nbsp; &nbsp; &nbsp; "item_cat":"Material",&nbsp; &nbsp; &nbsp; "items":[&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;{&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "item_name":"T-Shirt",&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "qty":"3"&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;},&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;{&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "item_name":"Cap",&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "qty":"5"&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;}&nbsp; &nbsp; &nbsp; ],&nbsp; &nbsp; &nbsp; "total":"2"&nbsp; &nbsp;}]现在没有 SQL 的数组循环（以确保它按预期工作）：$data = json_decode($json, true);$len = count($data);&nbsp; &nbsp; for($i =0; $i< $len; $i++){&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; $item_length = count($data[$i]['items']);&nbsp; &nbsp; &nbsp; &nbsp; for($c=0; $c < $item_length; $c++){&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; foreach ($data[$i]['items'][$c] as $key => $value ) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; $qty = '';&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if($key == "qty"){&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; $qty = $data[$i]['items'][$c];&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if($key == 'item_name'){&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; $item_name = "$value";&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }这里的问题是：非人类变量名称以及不正确使用 JSON 对象。首先，让我们将变量重命名为可读的名称。例子：$data[$i]将是$catalog_entry（对象）$data[$i]['items']将是$catalog_entry_items（数组）$data[$i]['items'][$c]将是$catalog_entry_item（一件物品，一个物体）让我们用新变量更改代码：$data = json_decode($json, true);$len = count($data);for($i =0; $i< $len; $i++) {&nbsp; &nbsp; $catalog_entry = $data[$i];&nbsp; &nbsp; $catalog_entry_items = $data[$i]['items'];&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; for($c=0; $c < sizeof($catalog_entry_items); $c++) {&nbsp; &nbsp; &nbsp; &nbsp; $catalog_entry_item = $data[$i]['items'][$c];&nbsp; &nbsp; &nbsp; &nbsp; $qty = $catalog_entry_item['qty'];&nbsp; &nbsp; &nbsp; &nbsp; $item_name = $catalog_entry_item['item_name'];&nbsp; &nbsp; &nbsp; &nbsp; echo $item_name . ' : ' . $qty . "\n"; // <-- this is for testing&nbsp; &nbsp; }}运行此代码并查看预期结果：A4 Paper : 2Test Paper : 6Power pack : 2T-Shirt : 3Cap : 5很好，现在我们有了qty和item_name。我们来查询一下。首先看看你的代码：$sql= $db->query("SELECT `stock` from `inventory` WHERE `item_name` = '$item_name'");&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; while ($sql1 = $sql->fetch_assoc()) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; $stock = $sql1['stock'];&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }两个奇怪的事情：1）可能的 SQL 注入，2）$stock用新值多次替换变量（如果我们有超过 1 行的项目inventory）。无论如何，如果这段代码有效（我无法检查），那么我们进入下一部分：if ($stock > $qty ) {&nbsp; &nbsp; $stock_balance = $stock - $qty;&nbsp; &nbsp; $quantity = (int)$qty;&nbsp; &nbsp; $db->query("UPDATE `inventory` SET `stock` =&nbsp; (`stock` - '$quantity')&nbsp; &nbsp;WHERE `item_name` = '$item_name'");} else {&nbsp; &nbsp; echo "<h3> This Operation Not Allowed: Stock Balance Is Less Than The Request <h3>";}首先，不必要地转换为整数，因此删除行$quantity = (int)$qty;并放入$stock_balance查询中。我们将有：if ($stock >= $qty ) {&nbsp; &nbsp; $stock_balance = $stock - $qty;&nbsp; &nbsp; $db->query("UPDATE `inventory` SET `stock` =&nbsp; $stock_balance WHERE `item_name` = '$item_name'");} else {&nbsp; &nbsp; echo "<h3> This Operation Not Allowed: Stock Balance Is Less Than The Request <h3>";}……好吧……不只是你累了，所以我现在就结束吧。询问是否有什么不正确或不理解的地方。