未处理的异常：NoSuchMethodError：在 null 上调用了方法“addAdvogado”。 关于颤振

Question

I researched other similar questions with this error but I couldn't fix it. I don't know what I'm doing wrong. My application is not saving to the database when I try to send the information to the form. What should I do to correct?

I receive the message:

Unhandled Exception: NoSuchMethodError: The method 'addAdvogado' was called on null. E/flutter ( 7418): Receiver: null E/flutter ( 7418): Tried calling: addAdvogado(Instance of 'Advogado')

lawyer.dart

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

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

  Advogado.fromMap(Map snapshot, String id)
      : id = snapshot['id'] ?? '',
        nome = snapshot['nome'] ?? '',
        email = snapshot['email'] ?? '',
        telefone = snapshot['telefone'] ?? '',
        endereco = snapshot['endereco'] ?? '',
        numeroOAB = snapshot['numeroOAB'] ?? '';

  toJson() {
    return {
      "id": id,
      "nome": nome,
      "email": email,
      "telefone": telefone,
      "endereco": endereco,
      "numeroOAB": numeroOAB,
    };
  }
}

form_lawyer.dart - Sample code

final _formAdvogado = GlobalKey<FormState>();

  final Map<String, String> _dadosForm = {};
    Container(
                margin: EdgeInsets.all(10.0),
                child: RaisedButton(
                  onPressed: () async {
                    if (_formAdvogado.currentState.validate()) {
                      _formAdvogado.currentState.save();
                      await advogadoProvider.addAdvogado(
                        Advogado(
                          nome: 'nome',
                          email: 'email',
                          telefone: 'telefone',
                          endereco: 'endereco',
                          numeroOAB: 'numeroOAB',
                        ),
                      );
                      Navigator.pop(context);
                    }
                  },
                  child: Text("Enviar"),
                  color: Colors.cyan,
                  textColor: Colors.white,
                ),

api_lawyer_firebase.dart

class ApiFirebase {
  // final FirebaseFirestore _bd = FirebaseFirestore.instance;
  final Future<FirebaseApp> _initialize = Firebase.initializeApp();
  FirebaseFirestore _bd = FirebaseFirestore.instance;
  final String path;
  CollectionReference ref;

  ApiFirebase(this.path) {
    ref = _bd.collection(path);
  }

  Future<QuerySnapshot> getColecaoDados() {
    return ref.get();
  }

  Stream<QuerySnapshot> streamColecaoDados() {
    return ref.snapshots();
  }

  Future<DocumentSnapshot> getDocumentoById(String id) {
    return ref.doc(id).get();
  }

  Future<void> removerDocumento(String id) {
    return ref.doc(id).delete();
  }

  Future<DocumentReference> addDocumento(Map dados) {
    return ref.add(dados);
  }

  Future<void> atualizarDocumento(Map dados, String id) {
    return ref.doc(id).update(dados);
  }
}

CRUD - database_laywer.dart

class DBAdvogado with ChangeNotifier {
  ApiFirebase _apiFirebase = locator<ApiFirebase>();

  List<Advogado> advogados;

  Future<List<Advogado>> buscarAdvogados() async {
    var result = await _apiFirebase.getColecaoDados();
    advogados =
        result.docs.map((doc) => Advogado.fromMap(doc.data(), doc.id)).toList();
    return advogados;
  }

  Stream<QuerySnapshot> buscarAdvogadoAsStream() {
    return _apiFirebase.streamColecaoDados();
  }

  Future<Advogado> getAdvogadoById(String id) async {
    var doc = await _apiFirebase.getDocumentoById(id);
    return Advogado.fromMap(doc.data(), doc.id);
  }

  Future removerAdvogado(Advogado dados, String id) async {
    await _apiFirebase.atualizarDocumento(dados.toJson(), id);
    return;
  }

  Future addAdvogado(Advogado dados) async {
    await _apiFirebase.addDocumento(dados.toJson());
    return;
  }
}

Answer 1

In general, when there is an error with "something" was called on null it means that the subject on which you are calling "something" is currently null.

You use addAdvogado method in one place on only one variable - in form_lawyer.dart on advogadoProvider . So the question is: how and where do you set advogadoProvider ?