php import excel file error function str_replace - php

Question

I have the code below, the purpose is to automatically add the product code.
For example, if the product code field is left blank, the default first product will be SP00001.
The next product will be SP00002...
The code still works fine with manually adding products. However, when I use the excel file to import data, I get the above code error.
The place where the product code runs is quite chaotic, only the first product is the code SP00001, then the full SP00002. The next time the code is entered, the codes are repeated a lot without knowing what's wrong. Thanks for your help.
public function cms_save_product($data){
$store_id = $this->auth['store_id'];
$data['user_init'] = $this->auth['id'];
if ($data['prd_code'] == '') {
$code = $this->db
->select('prd_code')
->from('products')
->like('prd_code', 'SP')
->order_by('created desc')
->get()
->row_array();
if(empty($code)){
$data['prd_code'] = 'SP00001';
}else{
$max_code = (int)(str_replace('SP', '', $code['prd_code'])) + 1;
if ($max_code < 10)
$data['prd_code'] = 'SP0000' . ($max_code);
else if ($max_code < 100)
$data['prd_code'] = 'SP000' . ($max_code);
else if ($max_code < 1000)
$data['prd_code'] = 'SP00' . ($max_code);
else if ($max_code < 10000)
$data['prd_code'] = 'SP0' . ($max_code);
else if ($max_code < 100000)
$data['prd_code'] = 'SP' . ($max_code);
}
}
$this->db->insert('products', $data);
}

Answer 1

It looks like you are using the record create date for ordering when looking for the greatest product code. If you are inserting many records in a loop while importing from a spreadsheet, and using something like datetime for your time format, this will cause your routine to generate the same code repeatedly until the next second ticks by. You should use something like:
SELECT MAX(prd_code) FROM products WHERE prd_code LIKE 'SP%'
for your query. This will ensure that you are always incrementing the highest product code.
You also have a problem where there is a maximum of 99999 product codes, which may be too low.
For the product code formatting, your logic can be greatly simplified by using str_pad.
This will completely replace empty codes with SP00001, and handle formatting the code with the correct number of zeroes in order to match the desired length.
$defaultCode = 'SP';
if (empty($code))
{
$data['prd_code'] = $defaultCode;
}
else
{
// Remove the SP prefix from the product code and cast to an int
$numCode = (int)(str_replace('SP', '', $code['prd_code']));
// Increment code
$numCode++;
/*
* Set the pad length to either the size of the default code, or the
* length of the stored product code plus 2 (for "SP" prefix), whichever is larger.
* This ensures that the codes always begin with SP even if they are longer than expected.
*/
$padLength = max(strlen($defaultCode), strlen($numCode) + 2);
// Format the product code using the default code as a left pad
$data['prd_code'] = str_pad($numCode, $padLength, $defaultCode, STR_PAD_LEFT);
}