PHP-ETL - Operations

Transform - Rule Transformer

The Rule Transformer operation builds a new associative array from an item’s data, one column at a time, by applying a Rule Engine rule to compute each column’s value.

Purpose

Use RuleTransformConfig to:

Reshape an item’s data into a new structure (rename, combine, or drop fields)
Compute derived columns (concatenation, case conversion, conditional values, …)
Either replace the item’s data entirely, or add computed columns alongside the existing data

Configuration

use Oliverde8\Component\PhpEtl\OperationConfig\Transformer\RuleTransformConfig;
use Oliverde8\Component\RuleEngine\RuleConfig\ExpressionRuleConfig;
use Oliverde8\Component\RuleEngine\RuleConfig\GetRuleConfig;
use Oliverde8\Component\RuleEngine\RuleConfig\ImplodeRuleConfig;

$config = (new RuleTransformConfig(add: false))
    ->addColumn('FullName', new ImplodeRuleConfig(
        values: [new GetRuleConfig('FirstName'), new GetRuleConfig('LastName')],
        with: ' ',
    ))
    ->addColumn('IsActive', new ExpressionRuleConfig(
        "rowData['IsSubscribed'] == 'yes'"
    ));

Parameters:

add (bool, default true): when true, computed columns are merged into the item’s existing data; when false, the item’s data is replaced entirely by the computed columns
addColumn(string $columnName, RuleConfigInterface|array $rules): registers one output column, computed by $rules. Call it once per column, in any order

addColumn() accepts either a typed RuleConfigInterface (see the Rule Engine page for the full catalog and Custom Rules for writing your own) or the legacy array-based rule syntax, which is deprecated — pass a RuleConfigInterface (e.g. new GetRuleConfig(...)) instead.

Example: Tagging Subscribed Customers

use Oliverde8\Component\PhpEtl\ChainConfig;
use Oliverde8\Component\PhpEtl\OperationConfig\Extract\CsvExtractConfig;
use Oliverde8\Component\PhpEtl\OperationConfig\Transformer\RuleTransformConfig;
use Oliverde8\Component\PhpEtl\OperationConfig\Loader\CsvFileWriterConfig;
use Oliverde8\Component\RuleEngine\RuleConfig\ExpressionRuleConfig;
use Oliverde8\Component\RuleEngine\RuleConfig\GetRuleConfig;
use Oliverde8\Component\RuleEngine\RuleConfig\ImplodeRuleConfig;

$chainConfig = new ChainConfig();
$chainConfig
    ->addLink(new CsvExtractConfig())
    ->addLink((new RuleTransformConfig(add: true))
        ->addColumn('FullName', new ImplodeRuleConfig(
            values: [new GetRuleConfig('FirstName'), new GetRuleConfig('LastName')],
            with: ' ',
        ))
        ->addColumn('IsActive', new ExpressionRuleConfig(
            "rowData['IsSubscribed'] == 'yes'"
        )))
    ->addLink(new CsvFileWriterConfig('customers-tagged.csv'));

Result: Every row keeps its original columns (add: true) plus two computed ones: FullName (first and last name joined by a space) and IsActive (a boolean derived from IsSubscribed).