layout: default title: Extracting data from a CSV

Extracting data

To extract data from a CSV document use League\Csv\Reader methods.

Fetching CSV data

query(callable $callable = null)

The query method prepares and issues queries on the CSV data. It returns an Iterator that represents the result that you can further manipulate as you wish.

$data = $reader->query();
foreach ($data as $lineIndex => $row) {
    //do something here
}

fetch(callable $callable = null)

The fetch method returns an Iterator.

foreach ($reader->fetch() as $row) {
    //do something here
}

fetchAll(callable $callable = null)

fetchAll returns a sequential array of all rows.

$data = $reader->fetchAll();
// will return something like this :
//
// [
//   ['john', 'doe', 'john.doe@example.com'],
//   ['jane', 'doe', 'jane.doe@example.com'],
//   ...
// ]
//
$nb_rows = count($data);

fetchAssoc($offset_or_keys = 0, callable $callable = null)

fetchAssoc returns a sequential array of all rows. The rows themselves are associative arrays where the keys are an one dimension array. This array must only contain unique string and/or integer values.

This array keys can be specified as the first argument as

• a specific CSV row by providing its offset; (since version 6.1)
• a non empty array directly provided;

Using a non empty array:

$data = $reader->fetchAssoc(['firstname', 'lastname', 'email']);
// will return something like this :
//
// [
//   ['firstname' => 'john', 'lastname' => 'doe', 'email' => 'john.doe@example.com'],
//   ['firstname' => 'jane', 'lastname' => 'doe', 'email' => 'jane.doe@example.com'],
//   ['firstname' => 'fred', 'lastname' => 'doe', 'email' => 'fred.doe@example.com'],
//   ...
// ]
//

Using a specific offset:

$data = $reader->fetchAssoc();
// will return something like this :
//
// [
//   ['john' => 'jane', 'doe' => 'doe', 'john.doe@example.com' => 'jane.doe@example.com'],
//   ['john' => 'fred', 'doe' => 'doe', 'john.doe@example.com' => 'fred.doe@example.com'],
//   ...
// ]
//

Of note:

• If the number of values in a CSV row is lesser than the number of named keys, the method will add null values to compensate for the missing values.
• If the number of values in a CSV row is greater that the number of named keys the exceeding values will be drop from the result set.
• If no argument is provided, the first row from the CSV data will be used
• If an offset is used, its content will be skipped in the result set.

fetchColumn($columnIndex = 0, callable $callable = null)

fetchColumn returns a sequential array of all values in a given column from the CSV data.

If for a given row the column does not exist, the row will be skipped.

$data = $reader->fetchColumn(2);
// will return something like this :
//
// ['john.doe@example.com', 'jane.doe@example.com', ...]
//

Using a callable to modify the returned resultset

The methods listed above (query, fetchAll, fetchAssoc, fetchColumn) can all take a optional callable argument to further manipulate each row before being returned. This callable function can take up to three parameters:

• the current csv row data
• the current csv key
• the current csv iterator object

$data = $reader->fetchAll(function ($row) {
    return array_map('strtoupper', $row);
});
// will return something like this :
//
// [
//   ['JOHN', 'DOE', 'JOHN.DOE@EXAMPLE.COM'],
//   ['JANE', 'DOE', 'JANE.DOE@EXAMPLE.COM'],
//   ...
// ]
//
$nb_rows = count($data);

fetchOne($offset = 0)

fetchOne return one single row from the CSV data. The required argument $offset represent the row index starting at 0. If no argument is given to the method it will return the first row from the CSV data.

$data = $reader->fetchOne(3); ///accessing the 4th row (indexing starts at 0)
// will return something like this :
//
//   ['john', 'doe', 'john.doe@example.com']
//

each(callable $callable)

each apply a callable function on each CSV row. The callable function:

• must return true to continue iterating over the CSV;
• can take up to three parameters:
  • the current csv row data;
  • the current csv key;
  • the current csv iterator object;

The method returns the number of successful iterations.

//re-create the fetchAll method using the each method
$res = [];
$func = null;
$nbIteration = $reader->each(function ($row, $index, $iterator) use (&$res, $func)) {
    if (is_callable($func)) {
        $res[] = $func($row, $index, $iterator);
        return true;
    }
    $res[] = $row;
    return true;
});