PHP library for creating/manipulating fixed-width text files

Question

We have a web application that does time-tracking, payroll, and HR. As a result, we have to write a lot of fixed-width data files for export into other systems (state tax filing

Answer 1

I don't know of any PHP library that specifically handles fixed-width records. But there are some good libraries for filtering and validating a row of data fields if you can do the job of breaking up each line of the file yourself.

Take a look at the Zend_Filter and Zend_Validate components from Zend Framework. I think both components are fairly self-contained and require only Zend_Loader to work. If you want you can pull just those three components out of Zend Framework and delete the rest of it.

Zend_Filter_Input acts like a collection of filters and validators. You define a set of filters and validators for each field of a data record which you can use to process each record of a data set. There are lots of useful filters and validators already defined and the interface to write your own is pretty straightforward. I suggest the StringTrim filter for removing padding characters.

To break up each line into fields I would extend the Zend_Filter_Input class and add a method called setDataFromFixedWidth(), like so:

class My_Filter_Input extends Zend_Filter_Input
{
    public function setDataFromFixedWidth($record, array $recordRules)
    {
        if (array_key_exists('regex', $recordRules) {
            $recordRules = array($recordRules);
        }

        foreach ($recordRules as $rule) {
            $matches = array();
            if (preg_match($rule['regex'], $record, $matches)) {
                $data = array_combine($rule['fields'], $matches);
                return $this->setData($data);
            }
        }

        return $this->setData(array());
    }

}

And define the various record types with simple regular expressions and matching field names. ICESA might look something like this:

$recordRules = array(
    array(
        'regex'  => '/^(A)(.{4})(.{9})(.{4})/',  // This is only the first four fields, obviously
        'fields' => array('recordId', 'year', 'federalEin', 'taxingEntity',),
    ),
    array(
        'regex'  => '/^(B)(.{4})(.{9})(.{8})/',
        'fields' => array('recordId', 'year', 'federalEin', 'computer',),
    ),
    array(
        'regex'  => '/^(E)(.{4})(.{9})(.{9})/',
        'fields' => array('recordId', 'paymentYear', 'federalEin', 'blank1',),
    ),
    array(
        'regex'  => '/^(S)(.{9})(.{20})(.{12})/',
        'fields' => array('recordId', 'ssn', 'lastName', 'firstName',),
    ),
    array(
        'regex'  => '/^(T)(.{7})(.{4})(.{14})/',
        'fields' => array('recordId', 'totalEmployees', 'taxingEntity', 'stateQtrTotal'),
    ),
    array(
        'regex'  => '/^(F)(.{10})(.{10})(.{4})/',
        'fields' => array('recordId', 'totalEmployees', 'totalEmployers', 'taxingEntity',),
    ),
);

Then you can read your data file line by line and feed it into the input filter:

$input = My_Filter_Input($inputFilterRules, $inputValidatorRules);
foreach (file($filename) as $line) {
    $input->setDataFromFixedWidth($line, $recordRules);
    if ($input->isValid()) {
        // do something useful
    }
    else {
        // scream and shout
    }
}

To format data for writing back to the file, you would probably want to write your own StringPad filter that wraps the internal str_pad function. Then for each record in your data set:

$output = My_Filter_Input($outputFilterRules);
foreach ($dataset as $record) {
    $output->setData($record);
    $line = implode('', $output->getEscaped()) . "\n";
    fwrite($outputFile, $line);
}

Hope this helps!