解释一下这段代码def price(request): if request.method == "GET": contact_list = models.zufang.objects.values_list().order_by('id') contact_list = [i for i in contact_list] new_contact_list = random.sample(contact_list, 3) user_name = models.Collection.objects.get(name=request.session.get('user_name')) if user_name.count > 0: collection = user_name.collection collection = collection.split(",") collection = [int(i) for i in collection] find_index = [] for item in collection: find_index.append(models.zufang.objects.values_list().filter(id=item)[0]) find_index = [i for i in find_index] else: collection = [] find_index = [] if request.GET.get("update_item") == "ok": return JsonResponse({"new_contact_list": new_contact_list, "find_index": find_index}, safe=False) return render(request, 'price.html', locals()) else: user_name = models.Collection.objects.get(name=request.session.get('user_name')) count = user_name.count if user_name.count > 0: collection = user_name.collection collection = collection.split(",") else: collection = [] if request.POST.get("new") == "true": count += 1 new_collection = request.POST.get("data_id") collection.append(new_collection) collection = ','.join(collection) new = models.Collection.objects.get(name=request.session.get('user_name')) new.collection = collection new.count = count new.save() else: count -= 1 new_collection = request.POST.get("data_id") collection.remove(new_collection) collection = ','.join(collection) new = models.Collection.objects.get(name=request.session.get('user_name')) new.collection = collection new.count = count new.save() return JsonResponse({}, safe=False)

这段代码是一个 Django 后端函数，名为 price，它处理 GET 和 POST 请求。对于 GET 请求，它从数据库中获取租房信息，并随机选取3个展示，并根据用户是否登录和是否已经收藏，返回对应的信息。对于 POST 请求，它根据用户的行为，将租房信息添加到或删除到用户的收藏列表中，并返回一个空的 JSON 响应。