如何使用 PHP 读取/写入 json 中的单个数组

Question

I have a simple script that can store data in a json file. Every time you save the form it creates a new array. I just want to update goal and raised in the same array.

form:

<form action="process.php" method="POST">
Goal:<br>
<input type="text" name="goal">
<br><br/>
Raised:<br>
<input type="text" name="raised">
<br><br>
<input type="submit" value="Submit">
</form>

process.php

<?php

$myFile = "data.json";
$arr_data = array();

try
{      
    $formdata = array(
        'goal'=> $_POST['goal'],
        'raised'=> $_POST['raised']
    );

    $jsondata = file_get_contents($myFile);

    $arr_data = json_decode($jsondata, true);

    array_push($arr_data,$formdata);

    $jsondata = json_encode($arr_data, JSON_PRETTY_PRINT);

    if(file_put_contents($myFile, $jsondata)) {
            echo 'Data successfully saved';
        }
    else 
            echo "error";

}
catch (Exception $e) {
            echo 'Caught exception: ',  $e->getMessage(), "\n";
}

?>

Answer 1

<?php

$formdata = array(
    'goal'=> $_POST['goal'],
    'raised'=> $_POST['raised']
);


try {

    $fp = fopen('data.json', 'w');
    fwrite($fp, json_encode($formdata));
    fclose($fp);

}
catch(\Exception $e) {
    // Caught Some Exception
}

You can simply use fopen() and fwrite() to open and write to a file. The data will be replaced with new data.

Answer 2

array_push appends. You want to replace existing, not add, right? So:

<?php

$myFile = "data.json";

try {      
    $arr_data = json_decode(file_get_contents($myFile), true);

    // don't forget to validate first of course:
    $arr_data['goal'] = $_POST['goal'];
    $arr_data['raised'] = $_POST['raised'];

    $jsondata = json_encode($arr_data, JSON_PRETTY_PRINT);

...

Answer 3

To Archive, this file_put_contents won't help much.

Whenever someone posts data from a form, you have to open your file(data.json) in append mode(a). then write your content using fwrite or fopen .

In this case, you will get all single data set as a separate array. Not a single array

Answer 4

When you do $arr_data = json_decode($jsondata, true); , $arr_data becomes an associative array, this means you can simply do $arr_data['goal'] = $_POST['goal'] or $arr_data['goal'] = $formdata['goal'] , after which you can re-encode the array and save it to your file. So you only need to switch the line with the array_push() call, to the code I've just explained. This works for both 'goal' and 'raised' keys