Passing variable from select element to JSON update function - PHP

Question

I'm trying to update individually loaded .json files according to whichever option in the <select> is chosen. It loads the .json file and then updates an individual file fine as long as I define $myFile as a specific .json file such as $myFile = "data/data.json";

But when I attempt to pass the select option as the filename, nothing saves. Where am I messing this up?

Here is the HTML select:

<form action="/server/php/data/process.php" method="post">
    <select class="ui mini fluid search dropdown" id="templateSelection" type="text" name="selectTemplate" onchange="loadTemplate()">
        <option value="" selected="selected">Select Template</option>
        <?php
            foreach(glob(dirname(__FILE__) . '/server/php/data/*') as $filename){
                $filename = basename($filename);
                echo "<option value='" . $filename . "'>".$filename."</option>";
            }
        ?>
   </select>
</form>

Here are the options that get populated:

<option value="data.json">data.json</option>
<option value="data2.json">data2.json</option>
<option value="data3.json">data3.json</option>

And here is process.php:

<?php

//$myFile = "data/data.json";
$filename = $_POST['selectTemplate'];
$myFile = "data/" . $filename;
$arr_data = array(); // create empty array
try
{
    //Get form data
    $formdata = array(
        'ID'=> $_POST['ID'],
        'attributeName'=> $_POST['attributeName'],
        'valueX'=> $_POST['valueX']
    );
    //Get data from existing json file
    $jsondata = file_get_contents($myFile);
    // converts json data into array
    $arr_data = json_decode($jsondata, true);
    $updateKey = null;
    foreach ($arr_data as $k => $v) {
        if ($v['ID'] == $formdata['ID']) {
            $updateKey = $k;
        }
    }
    if ($updateKey === null) {
        array_push($arr_data,$formdata);
    } else {
        $arr_data[$updateKey] = $formdata;
    }

    $jsondata = json_encode($arr_data);

    //write json data into data.json file
    if(file_put_contents($myFile, $jsondata)) {
        echo 'Data successfully saved';
    }
    else
        echo "error";
}
catch (Exception $e) {
    echo 'Caught exception: ',  $e->getMessage(), "\n";
}
?>

EDIT: I'm submitting it (with a submit button) via another form on the same page with the same action. This other form allows me to change some of the values of the json that is loaded when an option in the first form is selected. Here is what this second form looks like:

<form class="ui form" action="server/php/process.php" method="POST" target="frame"> .... <input type="submit" value="Save"> </form>

Perhaps that is where the issue is coming from? I figured a submit on this 2nd form would pick up the selected option in the first form and store the option in a variable.

I think the reason why you cannot modify data is the wrong path to file that is being saved. I assume that the php script cannot even read json content by the path from $myFile, can it? Additionally please check file permissions for write access as well. — Andy
– Andy, Commented Dec 29, 2017 at 15:19
I'll have to test whether it can read data from $myFile. I know that I do have write permissions because I can overwrite the json file if I uncomment $myFile = "data/data.json"; — Todd Williams
– Todd Williams, Commented Dec 29, 2017 at 15:37
The problem comes when I replace $myFile = "data/data.json"; with $filename = $_POST['selectTemplate']; $myFile = "data/" . $filename; — Todd Williams
– Todd Williams, Commented Dec 29, 2017 at 15:38
You should check what gets posted with your browser's dev tools. — Mathieu de Lorimier
– Mathieu de Lorimier, Commented Jan 11, 2018 at 18:09
If you're submitting by sumit button, what does the onchange="loadTemplate()" do? Any chance it messes up with select option values? — Sergey Benzenko
– Sergey Benzenko, Commented Jan 12, 2018 at 7:24

Heinrich Lee Yu · Accepted Answer · 2018-01-17 09:31:32Z

1

+50

When submitting HTML forms, browsers only post fields within the <form></form> tags.

Easy solution is to make all the fields under one form, or you can use Javascript to populate a hidden field on the actual form you are submitting.

answered Jan 17, 2018 at 9:31

Heinrich Lee Yu

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2 Comments

Greg Over a year ago

But the question clearly states that the select is inside the form tag.

Heinrich Lee Yu Over a year ago

He said the select is inside a form tag, but the submit button is in another form tag

michael - mlc · Accepted Answer · 2018-01-15 14:02:31Z

Try adding the submit button within the parent form of your select element (and remove the onchange handler for debugging).

As you wrote: "EDIT: I'm submitting it (with a submit button) via another form on the same page".

HTML-forms can not be nested and a submit button submits only the direct parent form (unless you use some javascript magic).

Note: In case you really want to submit the fields of 2 forms, have a look here:

Submit multiple forms with one submit button

Greg · Accepted Answer · 2018-01-18 13:19:13Z

1

The easiest way to debug it would be this:

var_dump($_POST);
$filename = $_POST['selectTemplate'];
var_dump($filename);
$myFile = "data/" . $filename;
var_dump($myFile);
$arr_data = array(); // create empty array

If it's the case that everything works when you hardcode $myFile = 'data/data.json - most probably one of those vars are not holding what you would expect them to hold.

answered Jan 18, 2018 at 13:19

Greg

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Comments

Jere · Accepted Answer · 2018-01-18 13:38:42Z

I understand, your actual HTML-Code looks something like this:

<form class="ui form" action="server/php/process.php" method="POST" target="frame">

    <form action="server/php/process.php" method="get">
        <select class="ui mini fluid search dropdown" id="templateSelection" type="text" name="selectTemplate" onchange="loadTemplate()">
            <option value="" selected="selected">Select Template</option>
            <option value="data.json">data.json</option>
            <option value="data2.json">data2.json</option>
            <option value="data3.json">data3.json</option>
       </select>
    </form>

<input type="submit" value="Save">
</form>

When you set the method='get' you can probably see, that your submit-button doesn't do anything. And here's why: Nested forms are not allowed in HTML. If you look at something like the Firefox-Inspector, you can how the browser is handling the exact same code:

As you can see, the browser removes the start of your inner <form>-tag and the end of your outer <form>-tag. In the result, your submit-button is outside of the form and is therefore useless.

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