How to Read and Write files using CodeIgniter - PHP

How to read a file

This post will explain how to read and write files using php. When reading a file from php, we can let the user select the file or we can give a specific file manually. Here is a explanation for reading and writing a csv file.

if (!empty($_POST) && $_POST['file_upload']) {

    $target_file = '/tmp/'  . basename($_FILES["file_name"]["name"]);

    $fileType = pathinfo($target_file,PATHINFO_EXTENSION);

    if($fileType =='csv'){

// read the csv file. Discussed below

}else{

    $this->session->set_flashdata('error_message', "Please upload valid file type");
}

Here we have check if the is a post(that means submit button has been pressed). Then we have uploaded the file to a folder called tmp. Then we check the file format(whether it is csv or not).  

Then we set some config

$config['upload_path'] = '/tmp';

$config['allowed_types'] = '*';

$config['max_size'] = '3024000';

$config['max_filename'] = '255';

$config['encrypt_name'] = TRUE;

When we read the csv, it gives a row as one array, columns are separated by a comma.

We open the csv file by using fopen

$file = '/tmp/' . $file['file_name'];

$file_handle = fopen($file, 'r');

We read file row by row and store each row as an array in a array. The columns are separated by using a comma. This process continuous until end of the file and then close the file.

$pieces = array();

while (!feof($file_handle)) {

    $line_of_text = fgetcsv($file_handle, 4096, $separator);

    if (is_array($line_of_text)) {

        $pieces[] = explode(",", implode($line_of_text));
    }
}
fclose($file_handle);

Use of $pieces[] = explode(",", implode($line_of_text)); is, when we get a row to an array, it needed to be breakdown by the comma. By using it we can individually call columns. $pieces[] contains the csv line by line.

How to write a file

First we give a name for the file and a path

$file_name = 'details.csv';
$file = FCPATH.'assets/csv/'.$file_name;

FCPATH is use to identify the full path (This file is stored in assets folder, csv folder).

Then we open the csv file.

$handle = fopen($file, 'a');

Here I have used “a” for append. It will only append the csv. That means it will write to the csv without clearing the whole csv. If we use “w” to write, it will delete all records in the csv and start write from the beging.

First of all, we can put a header title for the csv file.

$csvRow = array(

    'id', 'name', 'description', ...

);

$trimmed_array = array_map('trim', $csvRow);

fputcsv($handle, $trimmed_array);

By using fputcsv($handle, $trimmed_array); we can put a line to csv. Then by using a loop, we can put all data to csv as above and finally we close the file.
Hope you find this useful.

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