/**
* @author WN
* @param DataSources $dataSources
* @param Rule $rule
* @return Value
* @throws ProcessingException
*/
private function fetchValue(DataSources $dataSources, Rule $rule)
{
$source = $dataSources->getDataSource($rule->getSource());
if (!method_exists($source, $rule->getField())) {
throw new ProcessingException('Field [' . $rule->getField() . '] not exists in source [' . $rule->getSource() . ']');
}
$value = $source->{$rule->getField()}();
if (!$value instanceof Value) {
throw new ProcessingException('Field [' . $rule->getField() . '] in source [' . $rule->getSource() . '] must be Value type');
}
return $value;
}
