original_string: public function lessThanField($field, $secondField, $message = null, $when = null)
      {
          $extra = array_filter(['on' => $when, 'message' => $message]);
  
          return $this->add($field, 'lessThanField', $extra + [
              'rule' => ['compareFields', $secondField, Validation::COMPARE_LESS]
          ]);
      }
code: public function lessThanField($field, $secondField, $message = null, $when = null)
      {
          $extra = array_filter(['on' => $when, 'message' => $message]);
  
          return $this->add($field, 'lessThanField', $extra + [
              'rule' => ['compareFields', $secondField, Validation::COMPARE_LESS]
          ]);
      }
code_tokens: public function lessThanField ( $ field , $ secondField , $ message = null , $ when = null ) { $ extra = array_filter ( [ 'on' => $ when , 'message' => $ message ] ) ; return $ this -> add ( $ field , 'lessThanField' , $ extra + [ 'rule' => [ 'compareFields' , $ secondField , Validation :: COMPARE_LESS ] ] ) ; }
docstring: Add a rule to compare one field is less than another.
  
  @param string $field The field you want to apply the rule to.
  @param string $secondField The field you want to compare against.
  @param string|null $message The error message when the rule fails.
  @param string|callable|null $when Either 'create' or 'update' or a callable that returns
  true when the validation rule should be applied.
  @see \Cake\Validation\Validation::compareFields()
  @return $this
  @since 3.6.0
docstring_tokens: Add a rule to compare one field is less than another .