PHP fill up an associative array - php

Question

I'm creating a data.php file which returns a json file to a html file where I fill up a grid with the data from the data.php file.
I need this to be an associative array in the following form:
[
{"CompanyName":"Alfreds Futterkiste","ContactName":"Maria Anders","ContactTitle":"Sales Representative"},
{"CompanyName":"Ana Trujillo Emparedados y helados","ContactName":"Ana Trujillo","ContactTitle":"Owner"},
{"CompanyName":"Antonio Moreno Taquera","ContactName":"Antonio Moreno","ContactTitle":"Owner"}
]
Now the problem is, I want this data.php to be sort of generic, which means I don't know the columnnames nor the the amount of columns.
The only way I get this done, is by using a switch statement but this is not ideal (because I can make a number of cases but what if the table has one more column) nor is it very elegant.
I bet this can be done far better, any ideas ?
I tried using array_push() but that doesn't work with associative arrays.
// get columnnames
for ($i = 0; $i < $result->columnCount(); $i++) {
$col = $result->getColumnMeta($i);
$columns[] = $col['name'];
}
// fill up array
while ($row = $result->fetch(PDO::FETCH_ASSOC)) {
switch (count($columns);) {
case 1 :
$records[] = array($columns[0] => $row[$columns[0]]);
break;
case 2 :
$records[] = array($columns[0] => $row[$columns[0]], $columns[1] => $row[$columns[1]]);
break;
case 3 :
$records[] = array($columns[0] => $row[$columns[0]], $columns[1] => $row[$columns[1]], $columns[2] => $row[$columns[2]]);
break;
case ... // and so on
}
}
// send data to client
echo json_encode($records);

Answer 1

change the switch code segment with this one
$arr_tmp = array();
for($i = 0; $i < count($columns); $i++)
{
$arr_tmp[$columns[$i]] = $row[$columns[$i]];
}
$records []= $arr_tmp;

Answer 2

You could iterate over the columns:
while ($row = $result->fetch(PDO::FETCH_ASSOC)) {
$values = array();
foreach ($columns as $column) {
values[$column] = $row[$column];
}
records[] = $values;
}