Firebase 向Cloud Firestore添加阵列（颤振/飞镖）

您好，我正在尝试向我的收藏中添加一个名为“fitbit_activity”的文档，该文档包含一个距离数组，这是我基于fitbit的JSON自行制作的模型。下面是模型的样子：

class Distances {
  String activity;
  var distance;

  Distances({this.activity, this.distance});

  factory Distances.fromJson(Map<String, dynamic> parsedJson) {
    return Distances(
        activity: parsedJson['activity'],
        distance: parsedJson['distance'].toDouble());
  }
}

Here is what the API Response for 'Distances' Look like : 

最后，这是我将数据添加到firestore数据库的代码：

db = Firestore.instance();
    await db
        .collection('users')
        .document(userData[index].uID)
        .collection('fitbit_activity')
        .document(DateFormat.yMMMd().format(today))
        .setData({
      'caloriesBMR': _fitbitActivityApiVar.summary.caloriesBMR,
      'caloriesBurned': _fitbitActivityApiVar.summary.caloriesBurned,
      'fairlyActiveMinutes': _fitbitActivityApiVar.summary.lightlyActiveMinutes,
      'lightlyActiveMinutes': _fitbitActivityApiVar.summary.fairlyActiveMinutes,
      'veryActiveMinutes': _fitbitActivityApiVar.summary.veryActiveMinutes,
      'sedentaryMinutes': _fitbitActivityApiVar.summary.sedentaryMinutes,
      'steps': _fitbitActivityApiVar.summary.steps,
      'restingHeartRate': _fitbitActivityApiVar.summary.restingHeartRate,
      'distances': _fitbitActivityApiVar.summary.distances //I am getting an error here
    });

以下是错误：

E/flutter ( 4149): [ERROR:flutter/lib/ui/ui_dart_state.cc(148)] Unhandled Exception: Invalid argument: Instance of 'Distances'
E/flutter ( 4149): #0      StandardMessageCodec.writeValue 
package:flutter/…/services/message_codecs.dart:392
E/flutter ( 4149): #1      FirestoreMessageCodec.writeValue 
package:cloud_firestore/src/firestore_message_codec.dart:64
E/flutter ( 4149): #2      StandardMessageCodec.writeValue 
package:flutter/…/services/message_codecs.dart:382
E/flutter ( 4149): #3      FirestoreMessageCodec.writeValue 
package:cloud_firestore/src/firestore_message_codec.dart:64
E/flutter ( 4149): #4      StandardMessageCodec.writeValue.<anonymous closure> 
package:flutter/…/services/message_codecs.dart:389
E/flutter ( 4149): #5      _LinkedHashMapMixin.forEach  (dart:collection-patch/compact_hash.dart:377:8)
E/flutter ( 4149): #6      StandardMessageCodec.writeValue 
package:flutter/…/services/message_codecs.dart:387
E/flutter ( 4149): #7      FirestoreMessageCodec.writeValue 
package:cloud_firestore/src/firestore_message_codec.dart:64
E/flutter ( 4149): #8      StandardMessageCodec.writeValue.<anonymous closure> 
package:flutter/…/services/message_codecs.dart:389
E/flutter ( 4149): #9      _LinkedHashMapMixin.forEach  (dart:collection-patch/compact_hash.dart:377:8)
E/flutter ( 4149): #10     StandardMessageCodec.writeValue 
package:flutter/…/services/message_codecs.dart:387
E/flutter ( 4149): #11     FirestoreMessageCodec.writeValue 
package:cloud_firestore/src/firestore_message_codec.dart:64
E/flutter ( 4149): #12     StandardMethodCodec.encodeMethodCall 
package:flutter/…/services/message_codecs.dart:524
E/flutter ( 4149): #13     MethodChannel.invokeMethod 
package:flutter/…/services/platform_channel.dart:311
E/flutter ( 4149): <asynchronous suspension>
E/flutter ( 4149): #14     DocumentReference.setData 
package:cloud_firestore/src/document_reference.dart:51

E/flatter（4149）：[错误：flatter/lib/ui/ui\u dart\u state.cc（148）]未处理的异常：无效参数：“距离”的实例
E/flatter（4149）：#0 StandardMessageCodec.writeValue
软件包：flatter/../services/message\u编解码器。dart:392
E/flatter（4149）：#1 FirestoreMessageCodec.writeValue
包：cloud\u firestore/src/firestore\u message\u codec.dart:64
E/flatter（4149）：#2 StandardMessageCodec.writeValue
软件包：flatter/../services/message_codecs.dart:382
E/flatter（4149）：#3 FirestoreMessageCodec.writeValue
包：cloud\u firestore/src/firestore\u message\u codec.dart:64
E/flatter（4149）：#4 StandardMessageCodec.writeValue。
软件包：flatter/../services/message\u codecs.dart:389
E/flatter（4149）：#5 LinkedHashMapMixin.forEach（dart:collection patch/compact_hash.dart:377:8）
E/flatter（4149）：#6 StandardMessageCodec.writeValue
软件包：flatter/../services/message_codecs.dart:387
E/flatter（4149）：#7 FirestoreMessageCodec.writeValue
包：cloud\u firestore/src/firestore\u message\u codec.dart:64
E/flatter（4149）：#8 StandardMessageCodec.writeValue。
软件包：flatter/../services/message\u codecs.dart:389
E/flatter（4149）：#9 LinkedHashMapMixin.forEach（dart:collection patch/compact_hash.dart:377:8）
E/flatter（4149）：#10 StandardMessageCodec.writeValue
软件包：flatter/../services/message_codecs.dart:387
E/flatter（4149）：#11 FirestoreMessageCodec.writeValue
包：cloud\u firestore/src/firestore\u message\u codec.dart:64
E/flatter（4149）：#12 StandardMethodCodec.encodeMethodCall
软件包：flatter/../services/message\u编解码器。dart:524
E/颤振（4149）：#13方法Channel.invokeMethod
包装：颤振/../services/平台\通道。dart:311
E/颤振（4149）：
E/颤振（4149）：#14文件参考.setData
包：cloud\u firestore/src/document\u reference.dart:51

---

我是否应该在地图中写一个循环，以便将其添加到数据库中？任何帮助都将不胜感激！提前谢谢你

看起来您的

distance

类缺少序列化方法

添加一个执行以下操作的

toJson

方法：

类距离{
...
映射到JSON（）{
返回{
“活动”：活动，
“距离”：距离，
};
}
}

然后，在将数据存储到Firestore之前，必须为数组中的每个项添加对该方法的调用

。。。
“距离”：fitbitActivityApiVar
.摘要
.距离
.map（（距离）=>distance.toJson（））
.toList（），
});

---

希望对您有用

谢谢！这管用！我应该为我应该在数据库中编写的所有数组的所有Json类添加一个序列化方法吗？不客气，在所有应该存储到数据库的模型上实现

toJson

方法是一个很好的做法。它使您在将来更容易重构和更新您的模型。好的，非常感谢！

E/flutter ( 4149): [ERROR:flutter/lib/ui/ui_dart_state.cc(148)] Unhandled Exception: Invalid argument: Instance of 'Distances'
E/flutter ( 4149): #0      StandardMessageCodec.writeValue 
package:flutter/…/services/message_codecs.dart:392
E/flutter ( 4149): #1      FirestoreMessageCodec.writeValue 
package:cloud_firestore/src/firestore_message_codec.dart:64
E/flutter ( 4149): #2      StandardMessageCodec.writeValue 
package:flutter/…/services/message_codecs.dart:382
E/flutter ( 4149): #3      FirestoreMessageCodec.writeValue 
package:cloud_firestore/src/firestore_message_codec.dart:64
E/flutter ( 4149): #4      StandardMessageCodec.writeValue.<anonymous closure> 
package:flutter/…/services/message_codecs.dart:389
E/flutter ( 4149): #5      _LinkedHashMapMixin.forEach  (dart:collection-patch/compact_hash.dart:377:8)
E/flutter ( 4149): #6      StandardMessageCodec.writeValue 
package:flutter/…/services/message_codecs.dart:387
E/flutter ( 4149): #7      FirestoreMessageCodec.writeValue 
package:cloud_firestore/src/firestore_message_codec.dart:64
E/flutter ( 4149): #8      StandardMessageCodec.writeValue.<anonymous closure> 
package:flutter/…/services/message_codecs.dart:389
E/flutter ( 4149): #9      _LinkedHashMapMixin.forEach  (dart:collection-patch/compact_hash.dart:377:8)
E/flutter ( 4149): #10     StandardMessageCodec.writeValue 
package:flutter/…/services/message_codecs.dart:387
E/flutter ( 4149): #11     FirestoreMessageCodec.writeValue 
package:cloud_firestore/src/firestore_message_codec.dart:64
E/flutter ( 4149): #12     StandardMethodCodec.encodeMethodCall 
package:flutter/…/services/message_codecs.dart:524
E/flutter ( 4149): #13     MethodChannel.invokeMethod 
package:flutter/…/services/platform_channel.dart:311
E/flutter ( 4149): <asynchronous suspension>
E/flutter ( 4149): #14     DocumentReference.setData 
package:cloud_firestore/src/document_reference.dart:51