更新JSON值(如果存在)，否则将其添加到PHP中 [英] Update JSON value if exists otherwise add it in PHP

问题描述

我有一个包含以下内容的JSON文件:

I have a JSON file that contains the following:

{"faqitem": [{ "id": "faq1", "question": "Question 1"}]}

我正在尝试做两件事.如果存在特定值，则更新它；如果不存在，则添加一个新值.

I am trying to do two things. Update a particular value if it exists OR add a new value if it doesn't.

当前，我能够更新文件，但它只会不断添加新值，如果已经存在，则永远不会更新.

Currently, I am able to update the file, but it just keeps adding new values and never updates if it already exists.

$faqpage = 'includes/faq.json';

$file = file_get_contents($faqpage);    
$obj = json_decode($file); 

$newdata['id'] = "faq2";
$newdata['question'] = "This is the second question";

foreach($obj->faqitem as $key => $val ) {
   echo "IDS " . $val->id . " = " . $newdata['id'] . "<br/>\n";
   if ($val->id == $newdata['id']) {
     $val->question = $newdata['question'];
     echo $val->id . "<br/>match<br/>";
   } else {
         $newstuff = new stdClass;
     $newstuff->id = $newdata['id'];
     $newstuff->question = $newdata['question'];     
     array_push($obj->faqitem, $newstuff);
     echo "<br/>no match<br/>";
   }
}

echo json_encode($obj);

$fh = fopen($faqpage, 'w') or die ("can't open file");  
//okay now let's open our file to prepare it to write
fwrite($fh, json_encode($obj));
fclose($fh);

以下是带有重复对象ID的示例输出:

Here is an example output with duplicated object ids:

{"faqitem":[{"id":"faq1","question":"Question 1"},{"id":"faq2","question":"This is the updated question"},{"id":"faq2","question":"This is the updated question"}]}

推荐答案

您的问题是您的逻辑不正确.在第一次迭代中，ID不匹配，因此将添加$newdata.在第二次迭代中，ID匹配和项目将被更新-但请稍候.我们只是在先前的迭代中添加了该项目！因此，您的循环部分应如下所示:

Your problem is that your logic is incorrect. In the first iteration the ID doesn't match so $newdata will be added. In the second iteration the ID match and the item is going to be updated - but wait. We just added this item in previous iteration! So your loop part should looks like this:

...
$exists = false;
foreach($obj->faqitem as $key => $val)
{
    // update if exists
    if($val->id == $newdata['id']) {
        $val->question = $newdata['question'];
        $exists = true;
    }
}

// add new if not exists
if(!$exists) {
    $newstuff = new stdClass;
    $newstuff->id = $newdata['id'];
    $newstuff->question = $newdata['question'];     
    array_push($obj->faqitem, $newstuff);
}
...

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