flutter - 删除 firestore 表中的 map

Question

我在删除 Firestore 数据表中的 map 时遇到问题。实际上，我要么删除整个数组，要么收到以下类型的错误:

flutter: Failed to delete 1: Invalid argument: Instance of '_CompactLinkedHashSet '

我附上我的类(class)，以便您更好地理解。提前谢谢您

类删除_描述:

import 'package:cloud_firestore/cloud_firestore.dart';

class DeleteDescription {
  final String city;
  final String citee;
  final int value;
  CollectionReference cities = FirebaseFirestore.instance.collection('city');

  DeleteDescription(this.city, this.citee, this.value) {
    deleteDescription();
  }

  Future<void> deleteDescription() {
    return cities
        .doc(city)
        .collection("citee")
        .doc(citee)
        .set({
          "Description": FieldValue.arrayRemove([
            {0}
          ])
        })
        .then((value) => print("$citee Deleted"))
        .catchError((error) => print("Failed to delete $value: $error"));
  }
}

类(class)重述:

import 'package:ampc_93/fonction/firebase_crud/delete_description.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/material.dart';

class ReadDescription extends StatefulWidget {
  final String titreCity;
  final String titreCitee;

  ReadDescription(this.titreCity, this.titreCitee);

  @override
  _ReadDescriptionState createState() => _ReadDescriptionState();
}

class _ReadDescriptionState extends State<ReadDescription> {
  @override
  Widget build(BuildContext context) {
    CollectionReference cities = FirebaseFirestore.instance.collection("city");
    return FutureBuilder<DocumentSnapshot>(
      future: cities
          .doc(widget.titreCity)
          .collection("citee")
          .doc(widget.titreCitee)
          .get(),
      builder: (context, snapshot) {
        if (snapshot.hasError) {
          return Text("Something went wrong");
        }
        if (snapshot.hasData && !snapshot.data!.exists) {
          return Text("Documents does not exist");
        }
        if (snapshot.connectionState == ConnectionState.done) {
          var data = snapshot.data!.data() as Map<String, dynamic>;
          if (data["Description"] == null) {
            return Text("");
          } else {
            return ListView.separated(
                itemBuilder: (context, index) {
                  return ListTile(
                      title: Text(
                        data["Description"][index]["Identite"],
                        textAlign: TextAlign.justify,
                      ),
                      subtitle: Text(
                        data["Description"][index]["Role"],
                        textAlign: TextAlign.justify,
                        style: TextStyle(
                            decoration: TextDecoration.underline,
                            color: Colors.red),
                      ),
                      leading: Icon(Icons.person),
                      trailing: IconButton(
                        onPressed: () => DeleteDescription(
                            widget.titreCity, widget.titreCitee, index),
                        icon: Icon(Icons.delete_forever),
                        color: Colors.red[300],
                      ));
                },
                separatorBuilder: (context, index) => Divider(),
                itemCount: data["Description"].length);
          }
        }
        return Text("Loading");
      },
    );
  }
}

我指定在我的数据库中，“Description”是一个数组，因此我想删除例如“Description”编号为 0 的所有元素

Answer 1

您正在使用的 FieldValue.arrayRemove 无法以这种方式工作。从 firestore 列表中删除数据有两种方法。第一种方法是传递要删除的 FieldValue.arrayRemove 中的元素(不是索引)。第二种方法是从 firestore 获取集合并根据需要修改数据并更新 firestore 中的集合。查看下面的代码以获得更多理解。

import 'package:cloud_firestore/cloud_firestore.dart';

class DeleteDescription {
  final String city;
  final String citee;
  final int value;
  CollectionReference cities = FirebaseFirestore.instance.collection('city');

  DeleteDescription(this.city, this.citee, this.value) {
    deleteDescription();
  }

  Future<void> deleteDescription() {
   final snapshot = await cities.doc(city).collection("citee").doc(citee).get();
  
  /* Get list from firestore */
  final list = snapshot["Description"] as List;
 
  /* Remove first or any element and delete from list */
  list.removeAt(0);
  
  /* Update same list in firestore*/
  await cities
    .doc(city)
    .collection("citee")
    .doc(citee)
      .set({"Description": list}).then((value) => print(" Deleted"));

   
  }
}