PHP - How to debug empty response

Question

I'm starting to learn PHP and ran into something that I don't know how to debug...

I have two tables in my db, with following structures

wp_ad_management:

| id | template_id | date_from | date_to | img_url | ad_url | created_at |

and wp_ad_templates:

| id | name | proportions |

Here is my PHP to get data from them:

switch ($_GET['action']) {
  case 'all_ads':
    $result = mysqli_query($conn, "SELECT * FROM `wp_ad_management`");
    break;
  case 'all_templates':
    $result = mysqli_query($conn, "SELECT * FROM `wp_ad_templates`");
}

$data = array();
while ($row = mysqli_fetch_object($result)) {
  array_push($data, $row);
}

echo json_encode($data);

https://trevim.online/anuncios/php/get.php?action=all_ads everything is returned as expected https://trevim.online/anuncios/php/get.php?action=all_templates returns 200 but says no response data is available for this request.

I'm stuck on this for hours, reviewing all the code to try to understand what the difference is between one and the other! Please tell me how can one go about debugging this? There's no errors, nothing, just an empty response, when in fact I know that there are 6 entries in that templates table, which are returned if I run the same SQL directly in PHPMyAdmin.

Try Using mysqli_fetch_assoc instead of mysqli_fetch_object... You can see var_dump($row) to debug — sathish1409, Jun 05 '20 at 15:34
@Dharman mysqli_fetch_object returns Object where it is not an array. mysqli_fetch_assoc returns associative array — sathish1409, Jun 05 '20 at 15:38
@sathish1409 No, I meant in this situation. Why are you recommending it? — Dharman, Jun 05 '20 at 15:39
You need to check if you have any data at all in `wp_ad_templates` — Dharman, Jun 05 '20 at 16:52
I am closing this question with the closest related duplicate. It will give you some powerful debugging tools, that would help you in case of a real problem — Your Common Sense, Jun 05 '20 at 17:00

score -2 · Accepted Answer · edited Jun 05 '20 at 16:42

-2

Use mysqli_fetch_array to fetch a result row as an associative array.

switch ($_GET['action']) {
  case 'all_ads':
    $result = mysqli_query($conn, "SELECT * FROM `wp_ad_management`");
    break;
  case 'all_templates':
    $result = mysqli_query($conn, "SELECT * FROM `wp_ad_templates`");
}
$data = array();
while ($row = mysqli_fetch_array($result)) {
  array_push($data, $row);
}
echo json_encode($data);

edited Jun 05 '20 at 16:42

Dharman

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answered Jun 05 '20 at 16:07

Niraj Kumar

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Thanks, that did it! Could you please elaborate a bit on why it wasn't working and how to debug in these cases? – Henrique Saias Jun 05 '20 at 16:42
In mysqli you can use `fetch_all` instead of this loop – Dharman Jun 05 '20 at 16:42
1

@HenriqueSaias just to make it clear: there is **abolutely no difference** which means it worked by *accident*. Not to mention this answer says absolutely nothing on how to debug. – Your Common Sense Jun 05 '20 at 16:55

PHP - How to debug empty response

1 Answers1