如何从 Firebase Firestore 反序列化地图？

Question

我的 FirebaseFirestore 如下图所示

我的反序列化代码如下：

class StripeProductPlan extends Equatable {
  final DocumentReference selfRef;

  final Map<String, String> metaData;
  final String name;
  final String? role;
  final String? taxCode;

  const StripeProductPlan({
    required this.selfRef,
    required this.metaData,
    required this.name,
    this.role,
    this.taxCode,
  });

 factory StripeProductPlan.fromSnapshot(
      DocumentSnapshot<Map<String, dynamic>> snapshot) {
    final data = snapshot.data()!;
    return StripeProductPlan(
      metaData: data['metaData'] as Map<String, String>,
      selfRef: snapshot.reference,
      name: data['name'] as String,
      role: data['role'] as String? ?? '',
      taxCode: data['taxCode'] as String? ?? '',
    );
  }

除了元数据反序列化之外，其他一切都有效。我该如何解决这个问题？

Answer 1

要将 Firestore 文档中的元数据反序列化为 Dart 类，您可以定义与 Firestore 文档结构匹配的 Dart 模型类。根据您提供的图像，以下是如何定义 Dart 类并实现反序列化的示例：

class Metadata {
 final bool isTestingPlan;
  final int maxParticipants;
  final String orderIdx;
  final String productId;

  Metadata({
    required this.isTestingPlan,
    required this.maxParticipants,
    required this.orderIdx,
    required this.productId,
  });

  // Factory constructor to create an instance of Metadata from a Firestore document
  factory Metadata.fromFirestore(Map<String, dynamic> data) {
    return Metadata(
      isTestingPlan: data['isTestingPlan'] == 'true',
      maxParticipants: int.parse(data['maxParticipants']),
      orderIdx: data['orderIdx'],
      productId: data['productId'],
    );
  }

  // Method to convert the Metadata instance back to a Map
  Map<String, dynamic> toFirestore() {
    return {
      'isTestingPlan': isTestingPlan.toString(),
      'maxParticipants': maxParticipants.toString(),
      'orderIdx': orderIdx,
      'productId': productId,
    };
  }
}

现在，更新

StripeProductPlan

类以使用元数据类：

factory StripeProductPlan.fromSnapshot(DocumentSnapshot<Map<String, dynamic>> snapshot) {
    final data = snapshot.data()!;
    return StripeProductPlan(
      //you can change like this--------
      metaData: Metadata.fromMap(data['metadata'] as Map<String, dynamic>),
      selfRef: snapshot.reference,
      name: data['name'] as String,
      role: data['role'] as String? ?? '',
      taxCode: data['taxCode'] as String? ?? '',
    );
  }

Answer 2

我在你的截图中看到：

您的地图字段称为

medatadata

，而在您的班级中称为

metaData

，这是不正确的。字段名称必须匹配。看看区别吧，数据库中的字段以小写字母开头

d

，而类中的字段以大写字母开头

D.

要以最简单的方式解决此问题，请更改类中的字段名称以匹配数据库中的字段名称：

class StripeProductPlan extends Equatable {
  final DocumentReference selfRef;

  final Map<String, String> metadata; //👈
  final String name;
  final String? role;
  final String? taxCode;

  //...

}