Php merge object array getting wrongly only merge last values - php

Question

I am trying to merge an object as follows from set of values which comes from database as follows:
$pooldetails = array();
$qstncount = 5;
for($i=0;$i<$qstncount;$i++){
$stdClass = $DB->get_record_sql("SELECT * FROM {pool_objective} po WHERE (po.id = $randarray[$i])");
$pooldetails = (object) array_merge((array) $pooldetails, (array) $stdClass);
}
When I print outside as follows:
print_r($pooldetails);
I am getting only last value in this array. I mean the value of $qstncoun=4 .First 4 values are missing.What I am doing wrong?

Answer 1

It's expected actually. Quoting the docs:
If the input arrays have the same string keys, then the later value
for that key will overwrite the previous one.
To get the results combined, use array_merge_recursive() instead:
$arr1 = ['a' => 1];
$arr2 = ['a' => 2];
var_dump(array_merge($arr1, $arr2));
// ['a' => 2]
var_dump(array_merge_recursive($arr1, $arr2));
// ['a' => [1, 2]]
Be aware, however, of the following:
If the input arrays have the same string keys, then the values for
these keys are merged together into an array, and this is done
recursively, so that if one of the values is an array itself, the
function will merge it with a corresponding entry in another array
too. If, however, the arrays have the same numeric key, the later
value will not overwrite the original value, but will be appended.
It probably doesn't matter in your case, however, as keys map to column names. So you can use something like...
$pooldetails = array();
$qstncount = 5;
for($i=0;$i<$qstncount;$i++){
$stdClass = $DB->get_record_sql("SELECT * FROM {pool_objective} po WHERE (po.id = $randarray[$i])");
$pooldetails = array_merge_recursive($pooldetails, (array) $stdClass);
}
$pooldetails = (object) $pooldetails;