Flutter - message is only sent if all fields are filled

Question

When I try to send a message without an image, the Mailer shows an error, but if I take the field ..attachments.add(new Fileattachment(_imagemAn,)); the message is sent normally without presenting the error, however, the funny thing is that I am not getting it, if in that same message that was giving error by being sent without image, containing ..attachments.add(new Fileattachment(_imagemAn,));, just add an image and the message is sent.

it’s almost as if I was forced to send with image, I need to say that ..attachments.add(new Fileattachment(_imagemAn,)); equal to or different from nil?

I’m sweating the Mailer API: 4.0.0.

More directly, when the message is sent only if all fields are filled in, if one of the fields is not filled in, how to correct?

This is the code I’m using, this is the screen where the message is displayed before sending, as a confirmation page before sending.

class PaginadeBoasVindasAN extends StatelessWidget {

  String _localAn;
  String _problemaAn;
  File _imagemAn;
  File _imagemGaleriaAn;

  PaginadeBoasVindasAN(
    this._localAn,
    this._problemaAn,
    this._imagemAn,
    this._imagemGaleriaAn,
  );

  // Aqui vamos criar o e-mail - smtp

  enviarMensagem() async {
    String username = '@gmail.com';
    String password = '@#';

    final smtpServer = gmail(username, password);
    
    final message = Message()
      ..from = Address('Sem identificação', ' ')
      ..recipients.add('@gmail.com')
      ..ccRecipients.addAll(['[email protected]', '[email protected]'])
      ..bccRecipients.add(Address('[email protected]'))
      ..subject = '$_localAn :: ${DateTime.now()}'
      ..text = 'LOCAL: $_localAn,n\: $_problemaAn'
      ..attachments.add(FileAttachment(_imagemAn,))
      ..attachments.add(FileAttachment(_imagemGaleriaAn,));


    try {
      final sendReport = await send(message, smtpServer);
      print('Mensagem enviada: ' + sendReport.toString());
    } on MailerException catch (e) {
      print('Mensagem não enviada.');
      for (var p in e.problems) {
        print('Problema: ${p.code}: ${p.msg}');
      }
    }
    var connection = PersistentConnection(smtpServer);

    await connection.send(message);

    await connection.close();
  }

Answer 1

As you are starting, I leave as a hint, that go a little at a time, try to understand a little more about some points of the framework and language.

In your code, just process the image data to know whether or not to inform it, do the following:

class PaginadeBoasVindasAN extends StatelessWidget {

  String _localAn;
  String _problemaAn;
  File _imagemAn;
  File _imagemGaleriaAn;

  PaginadeBoasVindasAN(
    this._localAn,
    this._problemaAn,
    this._imagemAn,
    this._imagemGaleriaAn,
  );

  // Aqui vamos criar o e-mail - smtp

  enviarMensagem() async {
    String username = '@gmail.com';
    String password = '@#';

    final smtpServer = gmail(username, password);
    
    final message = Message()
      ..from = Address('Sem identificação', ' ')
      ..recipients.add('@gmail.com')
      ..ccRecipients.addAll(['[email protected]', '[email protected]'])
      ..bccRecipients.add(Address('[email protected]'))
      ..subject = '$_localAn :: ${DateTime.now()}'
      ..text = 'LOCAL: $_localAn,n\: $_problemaAn';

     if ((_imageAn != null) && (_imageAn != ""))
       message.attachments.add(FileAttachment(_imagemAn,));
     if ((_imagemGaleriaAn!= null) && (_imagemGaleriaAn!= ""))
       message.attachments.add(FileAttachment(_imagemGaleriaAn,));


    try {
      final sendReport = await send(message, smtpServer);
      print('Mensagem enviada: ' + sendReport.toString());
    } on MailerException catch (e) {
      print('Mensagem não enviada.');
      for (var p in e.problems) {
        print('Problema: ${p.code}: ${p.msg}');
      }
    }
    var connection = PersistentConnection(smtpServer);

    await connection.send(message);

    await connection.close();
  }

Explanation

Your code fails because you try to instill a FileAttachment() with an invalid or even NULL path.

Info

Use the .. just makes your code easier, so you don’t have to keep doing it all the time

message.metodoX()
message.metodoY()
message.metodoZ()

Can only do

message = Message()
..metodoX()
..metodoY()
..metodoZ()