>> 到列表? Flutter

In the last update of cloud_firestore, I get an error when I run the app with the old code. How can I convert a Stream<QuerySnapshot<Map<String, dynamic>,firebase,flutter,dart,google-cloud-firestore"/>

时间戳

首页 > 解决方案 > 如何转换流>> 到列表? Flutter

In the last update of cloud_firestore, I get an error when I run the app with the old code. How can I convert a Stream<QuerySnapshot<Map<String, dynamic>

firebase - 如何转换流>> 到列表? Flutter

In the last update of cloud_firestore, I get an error when I run the app with the old code. How can I convert a Stream<QuerySnapshot<Map<String, dynamic>

问题描述

In the last update of cloud_firestore, I get an error when I run the app with the old code. How can I convert a Stream<QuerySnapshot<Map<String, dynamic>>> to a List?

I have this code and I get null values:

Stream<List<Model>> getReviews(String id) {
try {
  return _collectionReference.doc(id).collection('reviews').orderBy('date', descending: true).snapshots().map((reviews) => reviews.docs.map((review) => Model.fromJson(review.data())));
} catch (error) {
  return error.message;
}

}

Turns out I was attempting to run reverse in a module that would cause circular import. The solution was to use reverse_lazy as suggested in the comments.

标签： firebaseflutterdartgoogle-cloud-firestore

解决方案

如果您只想在此处返回类似内容之前List<Model>使用get调用并等待结果：List<Model>

Future<List<Model>> getReviews(String id) {
try {
  QuerySnapshot querySnapshot=await _collectionReference.doc(id).collection('reviews').orderBy('date', descending: true).get();
  
  List<Model> result;
  querySnapshot.docs.forEach((doc) {
      print(doc["first_name"]);
      result.add(Model.fromJson(review.data()));
  });
  return result;
  
} catch (error) {
  return error.message;
}

确保以getReviews异步方式调用。

推荐阅读