I am unable to delete in Firebase database with Flutter

Question

I can’t seem to delete a data in Firebase personal. I created a CRUD I’m already connected with Firebase, the project is configured, and I was able to add some data. But I can’t delete it. It’s not working.

Follow my code below

Model class lawyer Dart.

class Advogado {
  String id;
  String nome;
  String email;
  String telefone;
  String endereco;
  String numeroOAB;

  Advogado(
      {this.id,
      this.nome,
      this.email,
      this.telefone,
      this.endereco,
      this.numeroOAB});

  Advogado.fromMap(DocumentSnapshot document) {
    id = document.id;
    nome = document.data()['nome'];
    email = document.data()['email'];
    telefone = document.data()['telefone'];
    endereco = document.data()['endereco'];
    numeroOAB = document.data()['numeroOAB'];
  }

  Map toMap() {
    var map = <String, dynamic>{};
    map['nome'] = nome;
    map['email'] = email;
    map['telefone'] = telefone;
    map['endereco'] = endereco;
    map['numeroOAB'] = numeroOAB;

    return map;
  }

  String documentId() => id;
}

CRUD class dbadvogad.Dart

class DBAdvogado with ChangeNotifier {
  DBAdvogado({this.fromMap, this.collection});

  final Advogado Function(DocumentSnapshot document) fromMap;
  Advogado advogado;

  String collection;

  CollectionReference collectionReference =
      FirebaseFirestore.instance.collection('advogado');

  Future<String> add(Advogado advogado) async {
    var collection = collectionReference;
    var document = await collection.add(advogado.toMap());
    return document.id;
  }

  Future<void> update(Advogado advogado) async {
    var collection = collectionReference;
    await collection.doc(advogado.documentId()).update(advogado.toMap());
  }

  Future<void> delete(String documentId) async {
    var collection = collectionReference;
    await collection.doc(documentId).delete();
  }

  Future<Advogado> getById(String documentId) async {
    var collection = collectionReference;
    var snapshot = await collection.doc(documentId).get();
    return fromMap(snapshot);
  }

  Future<List<Advogado>> getAll() async {
    var collection = collectionReference;
    List<Advogado> list = [];
    var querySnapshot = await collection.get();
    querySnapshot.docs.forEach((element) {
      list.add(fromMap(element));
    });

    return list;
  }

  CollectionReference filter() {
    return collectionReference;
  }

  List<Advogado> fromSnapshotToAdvogadoList(
      List<DocumentSnapshot> documentList) {
    List<Advogado> list = [];
    documentList.forEach((element) {
      list.add(fromMap(element));
    });
    return list;
  }
}

List that will appear the data to remove or edit

lawyer.

class ListaAdvogado extends StatelessWidget {

@override
  Widget build(BuildContext context) {
    var snapshots =
        FirebaseFirestore.instance.collection('advogado').snapshots();

    Advogado advogado = Advogado();
    DBAdvogado advogados = DBAdvogado();
    String documentId;

    return Scaffold(
      appBar: AppBar(
        title: Text('Lista de Advogados'),
        actions: <Widget>[
          IconButton(
            icon: Icon(Icons.add),
            onPressed: () {
              Navigator.of(context).pushNamed(
                RotasApp.FORM_ADVOGADO,
              );
            },
          ),
        ],
      ),
      body: StreamBuilder(
        stream: snapshots,
        builder: (
          BuildContext context,
          AsyncSnapshot<QuerySnapshot> snapshot,
        ) {
          if (snapshot.hasError) {
            return Center(child: Text('Erro: ${snapshot.error}'));
          }

          if (snapshot.connectionState == ConnectionState.waiting) {
            return Center(child: CircularProgressIndicator());
          }

          if (snapshot.data.docs.length == 0) {
            return Center(child: Text('Nenhuma tarefa ainda'));
          }

          return ListView.builder(
              itemCount: snapshot.data.docs.length,
              itemBuilder: (ctx, i) {
                var lista = snapshot.data.docs[i].data();
                return ListTile(
                  leading: CircleAvatar(child: Icon(Icons.person)),
                  title: Text(lista['nome']),
                  subtitle: Text(lista['email']),
                  trailing: Container(
                    width: 100,
                    child: Row(
                      children: <Widget>[
                        IconButton(
                          icon: Icon(Icons.edit),
                          color: Colors.green,
                          onPressed: () {
                            Navigator.of(context).pushNamed(
                              RotasApp.FORM_ADVOGADO,
                              arguments: advogado,
                              //advogado
                            );
                          },
                        ),
                        IconButton(
                          icon: Icon(Icons.delete),
                          color: Colors.red,
                          onPressed: () {
                            showDialog(
                              context: context,
                              builder: (ctx) => AlertDialog(
                                title: Text('Excluir Advogado'),
                                content: Text('Tem certeza???'),
                                actions: <Widget>[
                                  FlatButton(
                                    child: Text('Não'),
                                    onPressed: () =>
                                        Navigator.of(context).pop(false),
                                  ),
                                  FlatButton(
                                    child: Text('Sim'),
                                    onPressed: () =>
                                        Navigator.of(context).pop(true),
                                  ),
                                ],
                              ),
                            ).then((confirmed) async {
                              if (confirmed) {
                                await advogados.delete(documentId);                                  }
                            });
                          },
                        ),
                      ],
                    ),
                  ),
                );
              });
        },
      ),
    );
  }
}

Answer 1

You are switching to delete one documentId blank, because at no point are you feeding this property...

Here at this point:

await advogados.delete(documentId);

Change to:

If you have the firestore package in the latest version

await advogados.delete(snapshot.data.docs[i].id);

If you have the firestore package in an old version

await advogados.delete(snapshot.data.docs[i].documentId);