如何从event路由返回events路由时保留搜索表单数据？

问题核心是：从event页面返回events时，返回链接没有携带之前的bigcity和category筛选参数，导致筛选状态丢失。以下是两种可行的解决方案：

方案一：利用Session存储的筛选数据（推荐） #

你已经在search方法中将筛选数据存入了Session的searchFormData，直接读取该数据并传递到返回链接即可：

1. 修改EventController的event方法 #

注入SessionInterface，读取存储的筛选参数并传给模板：

#[Route('/event/{id}', name: 'event', methods: ['GET'])]
public function event(
    Event $event,
    UserRepository $userRepository,
    ParticipationRepository $participationRepository,
    SessionInterface $sessionInterface // 新增注入
){
    // 从Session获取之前的筛选数据，默认空数组避免报错
    $searchFormData = $sessionInterface->get('searchFormData', []);
    $bigcityId = $searchFormData['bigcity']?->getId() ?? null;
    $categoryId = $searchFormData['category']?->getId() ?? null;

    if ($this->getUser()) {
        $connected = $this->getUser();
        $useremail = $connected->getUserIdentifier();
        $user = $userRepository->findOneBy(['email' => $useremail]);

        // 改用findOneBy获取单个参与记录，避免返回数组
        if ($participation = $participationRepository->findOneBy(['participant' => $user, 'event' => $event])) {
            return $this->render('front/event.html.twig', [
                'event' => $event,
                'participation' => $participation,
                'bigcityId' => $bigcityId,
                'categoryId' => $categoryId
            ]);
        }
    }

    return $this->render('front/event.html.twig', [
        'event' => $event,
        'bigcityId' => $bigcityId,
        'categoryId' => $categoryId
    ]);
}

2. 修改event.html.twig的返回链接 #

在path函数中添加筛选参数：

<a href="{{ path('events', {'bigcity': bigcityId, 'category': categoryId}) }}">&lt; Retour</a>

3. 优化events方法的参数处理（可选） #

避免参数为空时出现错误，调整参数获取逻辑：

#[Route('/events', name: 'events')]
public function events(
    Request $request,
    EventRepository $eventRepository,
    CategoryRepository $categoryRepository,
    BigCityRepository $bigcityRepository,
    LocationRepository $locationRepository
){
    // 仅当参数存在时才查询实体
    $category = $request->query->get('category') 
        ? $categoryRepository->findOneById($request->query->get('category')) 
        : null;
    $bigcity = $request->query->get('bigcity') 
        ? $bigcityRepository->findOneById($request->query->get('bigcity')) 
        : null;
    
    // 修正原location查询逻辑，关联bigcity筛选
    $location = $bigcity ? $locationRepository->findBy(['bigcity' => $bigcity]) : $locationRepository->findAll();

    $events = $eventRepository->comingEventsList(['category' => $category, 'address' => $location]);

    return $this->render("front/events.html.twig", [
        'events' => $events,
        'category' => $category,
        'bigcity' => $bigcity
    ]);
}

方案二：通过URL传递筛选参数 #

如果不想依赖Session，可以在进入event页面时直接把筛选参数带在URL里：

1. 修改events.html.twig中的活动链接 #

添加bigcity和category参数：

<!-- 假设原活动链接是这样，追加筛选参数 -->
<a href="{{ path('event', {'id': event.id, 'bigcity': bigcity.id, 'category': category.id}) }}">查看活动详情</a>

2. 修改EventController的event方法 #

从Request中获取URL参数并传递给模板：

#[Route('/event/{id}', name: 'event', methods: ['GET'])]
public function event(
    Event $event,
    UserRepository $userRepository,
    ParticipationRepository $participationRepository,
    Request $request // 新增注入
){
    // 从URL查询参数中获取筛选值
    $bigcityId = $request->query->get('bigcity');
    $categoryId = $request->query->get('category');

    if ($this->getUser()) {
        $connected = $this->getUser();
        $useremail = $connected->getUserIdentifier();
        $user = $userRepository->findOneBy(['email' => $useremail]);

        if ($participation = $participationRepository->findOneBy(['participant' => $user, 'event' => $event])) {
            return $this->render('front/event.html.twig', [
                'event' => $event,
                'participation' => $participation,
                'bigcityId' => $bigcityId,
                'categoryId' => $categoryId
            ]);
        }
    }

    return $this->render('front/event.html.twig', [
        'event' => $event,
        'bigcityId' => $bigcityId,
        'categoryId' => $categoryId
    ]);
}

3. 修改event.html.twig的返回链接 #

和方案一一致，带上筛选参数：

<a href="{{ path('events', {'bigcity': bigcityId, 'category': categoryId}) }}">&lt; Retour</a>

额外优化：清理无用代码 #

在search方法的重定向中，events参数是多余的（无法通过路由传递对象数组），直接删除：

return $this->redirectToRoute("events", [
    'bigcity'=> $form->get('bigcity')->getData()->getId(), 
    'category'=> $form->get('category')->getData()->getId()
]);

内容的提问来源于stack exchange，提问作者Emilie Tossan