除了多过滤器搜索 Flutter Firebase 的 if else 语句之外，还有其他方法吗？

Question

我正在尝试在 Zillow 应用程序中实现多过滤器功能。我正在使用 Flutter、Firebase 和 Provider Package。

用户可以按价格范围、区域范围、城市、邮政编码、浴室、卧室和便利设施进行过滤。 用户可以选择任何过滤器组合。 当使用组合计算时，我最终得到了 127 个组合？

1. 是否有任何有效的方法来获取每个组合的查询？
2. 对于大量查询，Looping 或 Switch 语句是否是良好的代码实践？

---

 Future<void> getApartmentbyCityPrice(PersonalHomeList personalApartmentList,String city,double 
  maxPrice, double minPrice) async {
     if (city == "Any" && maxPrice != null && minPrice != null) {
         QuerySnapshot snapshot = await FirebaseFirestore.instance.collection('apartments'). 
          where("price",isGreaterThanOrEqualTo: minPrice, isLessThanOrEqualTo: maxPrice).get();
            List<PersonalApartment> _loadedPersonalApartment = [];
            snapshot.docChanges.forEach((result) {
            PersonalApartment personalApartment = new PersonalApartment(
            id: result.doc['id'],
            userId: result.doc['userId'],
            amenities: result.doc['amenities'],
            area: result.doc['area'],
            bathroom: result.doc['bathroom'],
            bedroom: result.doc['bedroom'],
            city: result.doc['city'],
            createdAt: result.doc['createdAt'],
            description: result.doc['description'],
            imageUrl: result.doc['imageUrl'],
            price: result.doc['price'],
            streetName: result.doc['streetName'],
            updatedAt: result.doc['updatedAt'],
            zipcode: result.doc['zipcode'],
          );
      _loadedPersonalApartment.add(personalApartment);
    });
   personalApartmentList.apartmentListByCity = _loadedPersonalApartment;
   } else if (city.isNotEmpty && city != "Any" && maxPrice == 0.0 && minPrice == 0.0) {
         QuerySnapshot snapshot = await FirebaseFirestore.instance.collection('apartments') 
         .where("city", isEqualTo: city).get();
          List<PersonalApartment> _loadedPersonalApartment = [];
          snapshot.docChanges.forEach((result) {
          PersonalApartment personalApartment = new PersonalApartment(
          id: result.doc['id'],
          userId: result.doc['userId'],
          amenities: result.doc['amenities'],
          area: result.doc['area'],
          bathroom: result.doc['bathroom'],
          bedroom: result.doc['bedroom'],
          city: result.doc['city'],
          createdAt: result.doc['createdAt'],
          description: result.doc['description'],
          imageUrl: result.doc['imageUrl'],
          price: result.doc['price'],
          streetName: result.doc['streetName'],
          updatedAt: result.doc['updatedAt'],
          zipcode: result.doc['zipcode'],
        );
        _loadedPersonalApartment.add(personalApartment);
     });
     personalApartmentList.apartmentListByCity = _loadedPersonalApartment;
   } else {
    QuerySnapshot snapshot = await FirebaseFirestore.instance.collection('apartments').where("city", 
    isEqualTo: city).where("price",isGreaterThanOrEqualTo: minPrice, isLessThanOrEqualTo: maxPrice)
    .get();
     List<PersonalApartment> _loadedPersonalApartment = [];
     snapshot.docChanges.forEach((result) {
     PersonalApartment personalApartment = new PersonalApartment(
       id: result.doc['id'],
       userId: result.doc['userId'],
       amenities: result.doc['amenities'],
       area: result.doc['area'],
       bathroom: result.doc['bathroom'],
       bedroom: result.doc['bedroom'],
       city: result.doc['city'],
       createdAt: result.doc['createdAt'],
       description: result.doc['description'],
       imageUrl: result.doc['imageUrl'],
       price: result.doc['price'],
       streetName: result.doc['streetName'],
       updatedAt: result.doc['updatedAt'],
       zipcode: result.doc['zipcode'],
      );
      _loadedPersonalApartment.add(personalApartment);
      });
       personalApartmentList.apartmentListByCity = _loadedPersonalApartment;
  }   
}

---

示例查询示例

  QuerySnapshot snapshot = await FirebaseFirestore.instance.collection('apartments').where("price", 
   isGreaterThanOrEqualTo: minPrice, isLessThanOrEqualTo: maxPrice).get();
  QuerySnapshot snapshot = await FirebaseFirestore.instance.collection('apartments').where("area", 
   isGreaterThanOrEqualTo: areaRange.start, isLessThanOrEqualTo: areaRange.end).get();
  QuerySnapshot snapshot = await FirebaseFirestore.instance.collection('apartments').
    where("bathroom", arrayContainsAny: bathroom).get();
  QuerySnapshot snapshot = await FirebaseFirestore.instance.collection('apartments').where("bedroom", 
    arrayContainsAny: bedroom).get();

---

过滤屏幕

[![过滤屏幕] [![过滤屏幕]

Answer 1

我想你正在使用 Firestore。

现在，您要根据以下条件在 Firestore 中查询公寓：

• 价值观
  • 城市
  • 邮政编码
• 范围
  • 价格范围
  • 区域范围
  • 浴室
  • 卧室
• 数组
  • 设施

你要做的是使用Compound Queries：

Query query = FirebaseFirestore.instance.collection('apartments');
if (city.isNotEmpty && city != "Any") {
  query = query.where("city", isEqualTo: city)
}
if (zipCode.isNotEmpty && zipCode != "Any") {
  query = query.where("zipCode", isEqualTo: zipCode)
}
...
QuerySnapshot snapshot = await query.get();
List<PersonalApartment> apartments = snapshot.docChanges.map(
  (result) => PersonalApartment.fromFirestore(result.doc),
);

您的主要问题是 Compound Queries 在 Firestore 中非常有限。限制之一是您不能在多个字段上组合范围过滤器。

因此，您只能在查询中执行一个范围过滤器，而在应用程序中执行另一个客户端。也许您可以确定范围过滤器的顺序，从最严格（将返回最小的一组公寓）到最一般的过滤器。

Query _buildQuery() {
  Query query = FirebaseFirestore.instance.collection('apartments');

  // SIMPLE QUERIES
  if (city.isNotEmpty && city != "Any") {
    query = query.where("city", isEqualTo: city)
  }
  if (zipCode.isNotEmpty && zipCode != "Any") {
    query = query.where("zipCode", isEqualTo: zipCode)
  }

  // RANGE QUERIES
  if (minPrice != null || maxPrice != null) {
    if (minPrice != null) {
      query = query.where("price", ">=", minPrice);
    }
    if (maxPrice != null) {
      query = query.where("price", "<=", maxPrice);
    }
    return query;
  }
  if (minArea != null || maxArea != null) {
    ...
    return query;
  }
  if (...) { ... }
  ...
  return query;
}

...

QuerySnapshot snapshot = await _buildQuery().get();
List<PersonalApartment> apartments = snapshot.docChanges.map(
  (result) => PersonalApartment.fromFirestore(result.doc),
);
apartments = apartments.where((apartment) { /* perform remaining filters clmient-side */ })