PHP: passing table row as hidden element in a form

Question

I'm trying to pass the result of a SELECT query as a hidden input element in a form. Actually, I'm creating a form for every row in the result.

I know that is possible passing a hidden array in a form, so I assume it should also work passing a row of a table.

This is a snippet of the code that handles it:

$res = $conn->query($query);
while($row = $res->fetch()) {

    echo '<form action="action.php" method="post">';

    foreach ($row as $element) {
        echo '<input type="hidden" name="row[]" value="'.$element.'">';
    }

    echo '<input type="submit" name="delete" value="Delete">';
    echo "</form>";
}

Now, the action.php script just prints the received row:

<?php
    echo "<pre>"; print_r($_POST['row']); echo "</pre>";
?>

The result of the query in mysql is

+--------+-------------+-----------+----------+------------+
| numero | id_producto | id_tienda | cantidad | f_pedido   |
+--------+-------------+-----------+----------+------------+
|      7 | IXUS115HSAZ |         3 |        2 | 2015-10-01 |
+--------+-------------+-----------+----------+------------+
1 row in set (0.01 sec)

But the print_r of the row in action.php doubles every field:

Array
(
    [0] => 7
    [1] => 7
    [2] => IXUS115HSAZ
    [3] => IXUS115HSAZ
    [4] => 3
    [5] => 3
    [6] => 2
    [7] => 2
    [8] => 2015-10-01
    [9] => 2015-10-01
)

My mistake must be somehow obvious, but I can't find where it is.

Take a look at this (php.net/manual/en/mysqli-result.fetch-array.php) by default you are fetching both numeric and associative — cmorrissey
– cmorrissey, Commented Nov 14, 2016 at 20:23
Is there a way to get the assoc array indexes as names in the action script? the print_r() shows only numeric indexes even though I use fetch(PDO::FETCH_ASSOC) in the form now. — rodrunner
– rodrunner, Commented Nov 14, 2016 at 20:34

u_mulder · Accepted Answer · 2016-11-14 21:05:48Z

2

You obviously use PDO

And as you can see from a manual - PDO fetch method takes as a first optional parameter a fetch_style.

And by default it is PDO::FETCH_BOTH which

returns an array indexed by both column name and 0-indexed column number as returned in your result set

So, you need to pass an argument to fetch either PDO::FETCH_ASSOC or PDO::FETCH_NUM:

while($row = $res->fetch(PDO::FETCH_ASSOC)) {

    // ... 

    // use `$field_name` to use  database field name
    foreach ($row as $field_name => $element) {
        echo '<input type="hidden" name="row[' . $field_name . ']" value="'.$element.'">';
    }

    // ...
}

edited Nov 14, 2016 at 21:05

answered Nov 14, 2016 at 20:29

u_mulder

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1 Comment

rodrunner Over a year ago

that works, but even if I use PDO::FETCH_ASSOC, the print_r($_POST['row']) in the action script shows always numeric indexes. Is there a way to make it work with the assoc indexes (i.e. $_POST['row']['id_producto'] instead of $_POST['row'][1] )?

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