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String Comparison Conditions

When to Use

Use StringComparisonBase when comparing two values using standard operators (equals, contains, starts with, regex, etc.). The base class provides operator selection and comparison logic; you only implement value retrieval.

Decision

CRITICAL: StringComparisonBase::evaluate() is FINAL. You CANNOT override it.

Override Method Purpose Return Type
getLeftValue() Retrieve left comparison value string
getRightValue() Retrieve right comparison value string

Pattern

#[EcaCondition(
  id: 'my_module_compare_values',
  label: new TranslatableMarkup('My Module: Compare Values'),
)]
class CompareValuesCondition extends StringComparisonBase {

  public function defaultConfiguration(): array {
    return [
      'left_value' => '',
      'right_value' => '',
    ] + parent::defaultConfiguration();
  }

  public function buildConfigurationForm(array $form, FormStateInterface $form_state): array {
    $form['left_value'] = [
      '#type' => 'textfield',
      '#title' => $this->t('Left value'),
      '#default_value' => $this->configuration['left_value'],
      '#eca_token_replacement' => TRUE,
    ];

    $form['right_value'] = [
      '#type' => 'textfield',
      '#title' => $this->t('Right value'),
      '#default_value' => $this->configuration['right_value'],
      '#eca_token_replacement' => TRUE,
    ];

    return parent::buildConfigurationForm($form, $form_state);
  }

  // REQUIRED: Override these, NOT evaluate()
  protected function getLeftValue(): string {
    return $this->tokenService->getOrReplace($this->configuration['left_value']);
  }

  protected function getRightValue(): string {
    return $this->tokenService->getOrReplace($this->configuration['right_value']);
  }
}

Common Mistakes

  • Wrong: Overriding evaluate() → Right: Fatal error (method is FINAL)
  • Wrong: Not calling parent::buildConfigurationForm() → Right: Missing operator dropdown
  • Wrong: Returning non-string from getLeftValue()/getRightValue() → Right: Type errors
  • Wrong: Forgetting token replacement → Right: Comparing literal strings instead of values
  • Wrong: Not handling NULL values → Right: Comparison failures

See Also

References: - Core: /modules/contrib/eca/src/Plugin/ECA/Condition/StringComparisonBase.php - Example: /modules/contrib/eca/modules/base/src/Plugin/ECA/Condition/ScalarComparison.php