使用Flutter将对象添加到Cloud Firestore [英] Adding an Object to Cloud Firestore using Flutter

问题描述

我想像这样在Flutter应用程序中向Google Cloud Firestore添加对象：

I want to add an object to Google Cloud Firestore in my Flutter app like this:

我已经进行了回复：

class Reply {
Reply(this.replyName, this.replyText, this.replyVotes);
  final String replyName;
  final String replyText;
  final String replyVotes;

  String getName() {
    return replyName;
  }

  String getText() {
    return replyText;
  }

  String getVotes() {
    return replyVotes;
  }
}

如何将Reply对象添加到Cloud Firestore？

How do I add a Reply object to cloud Firestore?

编辑：
为了澄清，我想创建一个数据类型为 Object <的字段。 / code>里面有字段：回复对象图片

推荐答案

首先，我强烈建议您使用一个定义所有模式和/或模型的文件，以便为您提供一个参考点db结构。就像某些名为dbSchema.dart的文件：

first, i highly recommend you have a single file that defines all of your schemas and/or models so there's a single point of reference for your db structure. like some file named dbSchema.dart:

import 'package:meta/meta.dart';

class Replies {

  final String title;  
  final Map coordinates;

  Replies({
    @required this.title,
    @required this.coordinates,
  });

 Map<String, dynamic> toJson() =>
  {
    'title': title,
    'coordinates': coordinates,
  };

}

并使要成为对象类型的字段成为对象类型地图。然后，在该页面上，您将插入db中，导入dbSchema.dart并创建一个新模型：

and make the field that you want to be an object type Map. then, on the page you're going to insert into the db, import dbSchema.dart and create a new model:

Replies _replyObj = new Replies(
  title: _topic,
  coordinates: _coordinates,
);

这假设您已在此之前定义了本地_coordinates（或其他）对象，例如：

this assumes you've defined your local _coordinates (or whatever) object prior to this, with something like :

_coordinates = {
 'lat': '40.0000',
 'lng': '110.000', 
};

然后要将其插入Firestore，请添加对象的toJson方法（您不能插入/更新普通Dart模型）：

and to then insert into Firestore, add the object's toJson method (you cannot insert/update a plain Dart model):

CollectionReference dbReplies = Firestore.instance.collection('replies');

Firestore.instance.runTransaction((Transaction tx) async {
  var _result = await dbReplies.add(_replyObj.toJson());
  ....

更新（5/31）

要转换将文档读回到对象中，您需要向类中添加 fromJson ，例如：

To convert the document read back into an object you need to add a fromJson to the class, like so:

Replies.fromJson(Map parsedJson) {
    id = parsedJson['id']; // the doc ID, helpful to have
    title = parsedJson['title'] ?? '';
    coordinates = parsedJson['coordinates'] ?? {};
}

因此，当您查询数据库时：

so when you query the db:

QuerySnapshot _repliesQuery = await someCollection
        .where('title', isEqualTo: _title)
        .getDocuments();

List<DocumentSnapshot> _replyDocs = _repliesQuery.documents;

您可以从每个快照中创建一个对象：

you can create an object out of each snapshot:

for (int _i = 0; _i < _replyDocs.length; _i++) {

  Replies _reply = Replies.fromJson(_replyDocs[_i].data);
  _reply.id = _replyDocs[_i].documentID;

  // do something with the new _reply object
}

这篇关于使用Flutter将对象添加到Cloud Firestore的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！