How to eliminate "Notice: Undefined offset: 1" errors while importing data from CSV file

Question

In this code today I am trying to update data in bulk. User uploads a CSV file, the system checks if the file type is correct, then fetches the data and updates the data accordingly with the help of a WHILE loop. Have a look at the code below.

if(isset($_POST['upload'])) {
if($_FILES['theFile']['name']) {
    $filename = explode(".", $_FILES['theFile']['name']);
    if(end($filename) == "csv") {
        $handle = fopen($_FILES['theFile']['tmp_name'], "r");
        while($file_data = fgetcsv($handle)) {
                $id = $DBcon->real_escape_string($file_data[0]);
                $newdate = $DBcon->real_escape_string($file_data[1]);
                $newdate = strtotime($newdate);
                $newdate = date('Y-m-d', $newdate);
                $query = "UPDATE IGNORE products SET expirydate='".$newdate."' WHERE id='".$vc."'";
                if ($DBcon->query($query)) {
                    $serror = "Customer Updatation Successful";
                } else {
                    $error = "Something Went Wrong - Contact Support";
                }
        }
        fclose($handle);
        $serror = "Successfully Fetched Details";
    } else {
        $error = "Please select a CSV file";
    }
} else {
    $error = "Please select a CSV file";
} 
}

The thing is everything works fine until we follow the rules. Let's have a look into the CSV file that works just fine.

123,11-06-2019
124,11-06-2019
125,11-06-2019
126,11-06-2019
127,11-06-2019

But when the CSV output does not includes a " , " between the columns it throws unwanted error. Here's the CSV file example

123 11-06-2019
124 11-06-2019
125 11-06-2019
126 11-06-2019
127 11-06-2019

Getting this error:

Okay
Notice
: Undefined offset: 1 in
D:\server\filepath\htdocs\filename.php
on line
21

Screenshot: http://prntscr.com/o4r9vi

The line 21 defines the next column in this case.

$newdate = $DBcon->real_escape_string($file_data[1]);

What can be done in this case to avoid/fix the error? I was thinking to throw an error when the file content does not meets certain requirements, such as when the file does not contains certain number of commas defining all the required/expected columns. But how can I do that exactly? I am pretty new to this part of PHP.

Thank you for your time.

Answer 1

You can start simply by doing a count on your $file_data variable to ensure that the number of fields you expect exist. You could also go further and check that the type of data you expect is valid. There is a library to do this called CSVUtils. Effectively the best all round approach is to first lint the CSV to ensure it conforms to RFC 4180. It should also be noted that there are issues with respect to PHPs fputcsv so if the CSVs are being generated by PHP in the first place linting could be an issue in some instances. To add to this if you wanted you could even check the mime type of the file first and also turn your notices into an exception. The solution to this can be found here.

Example of count.

if (count($file_data) < 2) {
    // do something (e.g. fill error array or throw exeption)
}