Craft\WorkflowController::actionApproveSubmission PHP Method

    public function actionApproveSubmission()
    {
        $user = craft()->userSession->getUser();
        $draftId = craft()->request->getParam('draftId');
        $submissionId = craft()->request->getParam('submissionId');
        $notes = craft()->request->getParam('notes');
        $model = craft()->workflow_submissions->getById($submissionId);
        $model->status = Workflow_SubmissionModel::APPROVED;
        $model->publisherId = $user->id;
        $model->dateApproved = new DateTime();
        $model->notes = $notes;
        // Check if we're approving a draft - we publish it too.
        if ($draftId) {
            $draft = craft()->entryRevisions->getDraftById($draftId);
        } else {
            $draft = null;
        }
        if (craft()->workflow_submissions->approveSubmission($model, $draft)) {
            craft()->userSession->setNotice(Craft::t('Entry approved and published.'));
        } else {
            craft()->userSession->setError(Craft::t('Could not approve and publish.'));
        }
        // Redirect page to the entry as its not a form submission - check for draft
        if ($draft) {
            // If we've published a draft the url has changed
            craft()->request->redirect($draft->cpEditUrl);
        } else {
            craft()->request->redirect(craft()->request->urlReferrer);
        }
    }