Php key is undefined, but there is key - php

Question

I am making my own array from another one, using email field as key value. If there is more results with same email I am amking array_push to existing key.
I am getting always data in my array (with email) and here is the example
Input data
Example data
$saved_data = [
0 => ['custom_product_email' => 'test#test.com',...],
1 => ['custom_product_email' => 'test#test.com',...],
2 => ['custom_product_email' => 'bla#test.com',...],
3 => ['custom_product_email' => 'bla#test.com',...],
...
];
Code
$data = [];
foreach ($saved_data as $products) {
$curVal = $data[$products->custom_product_email];
if (!isset($curVal)) {
$data[$products->custom_product_email] = [];
}
array_push($data[$products->custom_product_email], $products);
}
Error
I am getting error Undefined index: test#test.com and if I debug my array, there is key with value of 'test#test.com', so key is defined (!)
so var $curVal key is undefined
Result
So the goal of foreach is to filter all objects in array with same email, here is the example:
$data = [
'test#test.com' => [
0 => {data},
1 => {data},
...
],
'bla#test.com' => [
0 => {data},
1 => {data},
...
],
];

Answer 1

this line $curVal = $data[$products->custom_product_email]; is useless and is the one provoking the error: you just initialized $data as an empty array, logically the index is undefined.
You should test directly if (!isset($data[$products->custom_product_email])) {
Then explanation: there is a fundamental difference between retreiving the value of an array's index which is undefined and the same code in an isset. The latter evaluating the existence of a variable, you can put inside something that doesn't exist (like an undefined array index access). But you can't store it in a variable before the test.

Answer 2

Did you not see the error message?
Parse error: syntax error, unexpected '{' in ..... from this code
$saved_data = [
0 => {'custom_product_email' => 'test#test.com',...},
1 => {'custom_product_email' => 'test#test.com',...},
2 => {'custom_product_email' => 'bla#test.com',...},
3 => {'custom_product_email' => 'bla#test.com',...},
...
];
Change the {} to [] to correctly generate the array.
$saved_data = [
0 => ['custom_product_email' => 'test#test.com',...],
1 => ['custom_product_email' => 'test#test.com',...],
2 => ['custom_product_email' => 'bla#test.com',...],
3 => ['custom_product_email' => 'bla#test.com',...],
...
];
Your next issue is in this code
$data = [];
foreach ($saved_data as $products) {
$curVal = $data[$products->custom_product_email];
// ^^^^^
$data is an empty array that you initialised 2 lines above, so it does not contain any keys or data!

Answer 3

Check, if $data[$products->custom_product_email] is already set in $data array
Try This code
$data = [];
foreach ($saved_data as $products) {
$curVal = isset($data[$products->custom_product_email]) ? $data[$products->custom_product_email] : null;
if (!isset($curVal)) {
$data[$products->custom_product_email] = [];
}
array_push($data[$products->custom_product_email], $products);
}