php/mysql write array to json file

Question

I have the following issue, my php code gets the required data from the dB:

<?php

require('dB_connect.php');

$reportID = intval($_GET['q']);


$sql = "SELECT nmech, nelect, nplant, ncivil FROM `flashreport` WHERE ID = '".$reportID."'";
$result = mysqli_query($dbc, $sql);

$emparray = array();
while($row =mysqli_fetch_assoc($result))
{
    $emparray[] = $row;
}
file_put_contents("newport.json", json_encode($emparray,JSON_FORCE_OBJECT));

mysqli_close($dbc);

?>

As you see this writes to a json file - results:

{"0":{"nmech":"2.00","nelect":"2.00","nplant":"2.00","ncivil":"2.00"}}

When I use the following js code to extract from json file:

$.getJSON('newport.json', function(data) {
console.log(data);

The console log using chrome displays the following:

[Object]
0: Object
nmech: "3.00"
__proto__: Object
length: 1

only shows the first key/value pair and not all 4 K/V pair? Can someone explain what I am doing wrong please.

did you check if the file_put_contents succeeded? You're just assuming the updated json file was written. — Marc B
– Marc B, Commented Feb 11, 2016 at 19:44
Your value for nmech is not correct in your example while doing console log and in the file. — themightysapien
– themightysapien, Commented Feb 11, 2016 at 19:47
Tried console.log(data[0]); result is Object {nmech: "3.00"} — Kevin Sullivan
– Kevin Sullivan, Commented Feb 11, 2016 at 19:49

jjwdesign · Accepted Answer · 2016-02-11 19:57:50Z

1

Writing the results to a json file is overkill, IMHO. Why not just add the json into a Template or Page view (PHP).

<script>
    // Create settings from PHP/Session and 
    // Initialize Registration Namespace
    var registrationSettings = <?php echo (!empty($data)) ? @json_encode($data) : json_encode(array()); ?>;
    Registration.init({ settings: window.registrationSettings });
</script>

Obviously, you don't have a Registration namespace object, but this just an example approach to setting settings from PHP when the page first loads.

All you really need it to output some data.

<script>
    var newport = <?php echo (!empty($emparray)) ? @json_encode($emparray) : json_encode(array()); ?>;
</script>

Or maybe a more simple way to write it would be.

<script>
    var newport = <?php echo (!empty($emparray)) ? @json_encode($emparray) : '[]'; ?>;
</script>

I can see your trying to file (or cache) the results. You should probably just write an AJAX method in your PHP controller to handle the request. The data could be cached server side in Memcached or some other fast handler of data. Most PHP frameworks support memcached.

edited Feb 11, 2016 at 19:57

answered Feb 11, 2016 at 19:48

jjwdesign

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2 Comments

Kevin Sullivan Over a year ago

took your advice and wrote an AJAX method, works a treat, not sure why the jQuery wouldnt work?

jjwdesign Over a year ago

It could be the server is not serving up the json file with the correct header. With PHP you should set the header manually with: header('Content-type: application/json'); echo json_encode($output);

unalignedmemoryaccess · Accepted Answer · 2016-02-11 19:48:10Z

0

This is ok, because your PHP array looks like this:

<?php 
$arr = [
    [
        "key1" => "value1",
        "key2" => "value2",
    ]
]

You must use data[0]['key'] to access key1 part of first element.

Another (better solution) is to not to use while loop in php, since you are expecting 1 element in your case to be returned from mysql. Use like this then:

<?php
require('dB_connect.php');
$reportID = intval($_GET['q']);

$sql = "SELECT nmech, nelect, nplant, ncivil FROM `flashreport` WHERE ID = '".$reportID."'";
$result = mysqli_query($dbc, $sql);

//Get first row from db.
$emparray = mysqli_fetch_assoc($result);
file_put_contents("newport.json", json_encode($emparray,JSON_FORCE_OBJECT));

mysqli_close($dbc);
?>

Now your data will be in javascript like you expected on beginning.

answered Feb 11, 2016 at 19:48

unalignedmemoryaccess

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1 Comment

Kevin Sullivan Over a year ago

have tried what you suggested and this didn't work, still only outputs the same Object {nmech: "3.00"}

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