Flutter Firebase流无法正确返回数据

Question

使用提供方作为状态管理的流从firebase返回数据时遇到问题。

所有数据都是正确的，除了AppTemplate模型丢失了文档ID（id），我将其添加到模型中，您可以从下面的蒸汽中看到。在断点上

AppTemplate.fromSnapshot（data，documentId），

我可以看到它具有有效的ID

  //Method to retrieve all template items from the same user based on uid
  Stream<List<AppTemplate>> templatesStream() =>
      _firestoreService.collectionStream(
        path: FirestorePath.templates(uid),
        builder: (data, documentId) =>
            AppTemplate.fromSnapshot(data, documentId),
      );

但是，当它使用下面的Id字段返回数据时为null。这意味着我无法以任何方式处理文档，即。删除/更新。

                         StreamBuilder(
                              stream: firestoreDatabase.templatesStream(),
                              initialData: new List<AppTemplate>(),
                              builder: (context, snapshot) {
                                if (snapshot.data != null) {
                                  List<AppTemplate> templates = snapshot.data;
                                  return ListView.builder(
                                    physics:
                                        const NeverScrollableScrollPhysics(),
                                    shrinkWrap: true,
                                    itemBuilder: (context, index) {
                                      return ListTile(
                                        title: Text(templates[index].title),
                                        subtitle: Text(templates[index]
                                                        .description ==
                                                    null ||
                                                templates[index].description ==
                                                    ""
                                            ? "N/A"
                                            : templates[index].description),
                                        leading: Icon(Icons.collections),
                                        trailing: GestureDetector(
                                            onTap: () => {
                                                  firestoreDatabase
                                                      .deleteTemplate(
                                                          templates[index])
                                                },
                                            child: Icon(Icons.delete)),
                                      );
                                    },
                                    itemCount: templates.length,
                                  );
                                } else if (snapshot.hasError) {
                                  return Center(child: Text('Error'));
                                }
                                return Center(
                                    child: CircularProgressIndicator());
                              }),

这是我的应用模板模型：

class AppTemplate {
  String id;
  List<AppQuestion> questions;
  String title;
  String description;
  Timestamp createdOn;

  AppTemplate(
      {this.id, this.questions, this.title, this.description, this.createdOn});

  AppTemplate.fromData(Map<String, dynamic> json, String id) {
    id = id ?? '';
    ;
    title = json['title'];
    description = json['description'];
    createdOn = json['createdOn'];
    if (json['questions'] != null) {
      questions = new List<AppQuestion>();
      json['questions'].forEach((v) {
        questions.add(new AppQuestion.fromData(v));
      });
    }
  }

  AppTemplate.fromSnapshot(Map<String, dynamic> json, String id) {
    id = id ?? '';
    title = json['title'];
    description = json['description'];
    createdOn = json['createdOn'];
    if (json['questions'] != null) {
      questions = new List<AppQuestion>();
      json['questions'].forEach((v) {
        questions.add(new AppQuestion.fromData(v));
      });
    }
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['description'] = this.description;
    data['title'] = this.title;
    data['createdOn'] = this.createdOn;

    if (this.questions != null) {
      data['questions'] = this.questions.map((v) => v.toJson()).toList();
    }
    return data;
  }
}

预先感谢