Question

我正在尝试在flutter-app中测试firestore，但无法真正按预期加载数据。

这是我获取数据的方式：

InputStream

和打印语句输出：flutter：来自db的值：'DocumentSnapshot'的实例。

我也尝试了以下尝试，但没有成功：

getCacheDir()

这里的输出仅是documentID名称。

那么，我怎么能从firestore中获取字段值？

最诚挚的问候！

Answer 1

你好吗？我遇到了类似的问题，并以此方式解决了该问题：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.AspNetCore.SpaServices.Webpack;
using Microsoft.Extensions.Hosting;
using Microsoft.AspNetCore.Routing;
using Microsoft.AspNetCore.Mvc;

using OptionsAPI.Services;

namespace OptionsAPI
{
    public class Startup
    {
        // This method gets called by the runtime. Use this method to add services to the container.
        // For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
        public void ConfigureServices(IServiceCollection services)
        {
            var connectionString =
               "Server=xxx.xx.xx.xxx;Integrated Security=false;Trusted_Connection=false;Database=Options;User Id=xxx;Password=xxxxx";
               services.AddDbContext<OptionsDbContext>(o =>
                   o.UseSqlServer(connectionString));

            services.AddMvc();
            services.AddMvc(option => option.EnableEndpointRouting = false);    
        }

        //etc...

之后，我使用StreamBuilder来使用上面创建的方法：

Stream<DocumentSnapshot> provideDocumentFieldStream() {
    return Firestore.instance
        .collection('collection')
        .document('document')
        .snapshots();
}

Answer 2

尝试一下：

final String _collection = 'collectionName';
final Firestore _fireStore = Firestore.instance;

getData() async {
  return await _fireStore.collection(_collection).getDocuments();
}

getData().then((val){
    if(val.documents.length > 0){
        print(val.documents[0].data["field"]);
    }
    else{
        print("Not Found");
    }
});

Answer 3

空安全码：

一次读取数据：

var collection = FirebaseFirestore.instance.collection('Test');
var docSnapshot = await collection.doc('test').get();
if (docSnapshot.exists) {
  Map<String, dynamic>? data = docSnapshot.data();

  // You can then retrieve the value from the Map like this:
  var value = data?['your_field'];
}

持续监听数据：

var collection = FirebaseFirestore.instance.collection('Test');
collection.doc('test').snapshots().listen((docSnapshot) {
  Map<String, dynamic>? data = docSnapshot.data();
  if (docSnapshot.exists) {
    Map<String, dynamic>? data = docSnapshot.data();

    // You can then retrieve the value from the Map like this:
    var value = data?['your_field'];
  }
});

如何从扑扑的Firestore文档字段中获取数据？

3 个答案:

空安全码：