[dart-misc] Write to a file, ends up with zero bytes

[Jon Kleiser]

Hi,

I want to write some text to a file, and I have tried both methods given
at https://api.dartlang.org/stable/1.22.1/dart-io/File-class.html, both the
one using "writeAsString" and the one using "sink.write", but both ways I
end up with a completely empty file, zero bytes. Why is that happening?

/Jon

[Istvan Soos]

Hi Jon,

It might be possible that you are starting an async IO operation and
your program exits before it gets done. The following code should
work, because it awaits for the writeAsString() to be completed:

import 'dart:io';

main() async {
await new File('output.txt').writeAsString('content');
}

This article has a few more examples about Dart's IO uses:
https://www.dartlang.org/articles/dart-vm/io
Hope it helps.

Istvan

Hi,
I want to write some text to a file, and I have tried both methods given at
https://api.dartlang.org/stable/1.22.1/dart-io/File-class.html, both the one
using "writeAsString" and the one using "sink.write", but both ways I end up
with a completely empty file, zero bytes. Why is that happening?
/Jon
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[Jon Kleiser]

Thanks, Istvan. Yes, putting "await" in front of "new File" looks like it's
the way to go. I just have to figure out a nice way to do the rest of the
printing, unless I shall give the total content as one big string to
'writeAsString'.

/Jon

Post by Istvan Soos
Hi Jon,
It might be possible that you are starting an async IO operation and
your program exits before it gets done. The following code should
import 'dart:io';
main() async {
await new File('output.txt').writeAsString('content');
}
https://www.dartlang.org/articles/dart-vm/io
Hope it helps.
Istvan

Post by Jon Kleiser
Hi,
I want to write some text to a file, and I have tried both methods given

at

Post by Jon Kleiser
https://api.dartlang.org/stable/1.22.1/dart-io/File-class.html, both

the one

Post by Jon Kleiser
using "writeAsString" and the one using "sink.write", but both ways I

end up

Post by Jon Kleiser
with a completely empty file, zero bytes. Why is that happening?
/Jon
--
For other discussions, see https://groups.google.com/a/dartlang.org/
For HOWTO questions, visit http://stackoverflow.com/tags/dart
To file a bug report or feature request, go to

http://www.dartbug.com/new

Post by Jon Kleiser
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[Istvan Soos]

Keep in mind that the await is not "before" the "new File()", my code
was the short version of:

Future main() async {
File file = new File('output.txt');
Future f = file.writeAsString('content');
await f;
}

Post by Jon Kleiser
Thanks, Istvan. Yes, putting "await" in front of "new File" looks like it's
the way to go. I just have to figure out a nice way to do the rest of the
printing, unless I shall give the total content as one big string to
'writeAsString'.
/Jon

Post by Istvan Soos
Hi Jon,
It might be possible that you are starting an async IO operation and
your program exits before it gets done. The following code should
import 'dart:io';
main() async {
await new File('output.txt').writeAsString('content');
}
https://www.dartlang.org/articles/dart-vm/io
Hope it helps.
Istvan

Hi,
I want to write some text to a file, and I have tried both methods given at
https://api.dartlang.org/stable/1.22.1/dart-io/File-class.html, both the one
using "writeAsString" and the one using "sink.write", but both ways I end up
with a completely empty file, zero bytes. Why is that happening?
/Jon
--
For other discussions, see https://groups.google.com/a/dartlang.org/
For HOWTO questions, visit http://stackoverflow.com/tags/dart
To file a bug report or feature request, go to
http://www.dartbug.com/new
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['Filip Hracek' via Dart Misc]

If you want to write to the file part-by-part (instead of one huge String),
you can use File.sink. Just make sure you close it afterwards.

Filip Hráček
https://google.com/+filiphracek

Post by Jon Kleiser
Thanks, Istvan. Yes, putting "await" in front of "new File" looks like
it's the way to go. I just have to figure out a nice way to do the rest of
the printing, unless I shall give the total content as one big string to
'writeAsString'.
/Jon

Post by Istvan Soos
Hi Jon,
It might be possible that you are starting an async IO operation and
your program exits before it gets done. The following code should
import 'dart:io';
main() async {
await new File('output.txt').writeAsString('content');
}
https://www.dartlang.org/articles/dart-vm/io
Hope it helps.
Istvan

Post by Jon Kleiser
Hi,
I want to write some text to a file, and I have tried both methods

given at

Post by Jon Kleiser
https://api.dartlang.org/stable/1.22.1/dart-io/File-class.html, both

the one

Post by Jon Kleiser
using "writeAsString" and the one using "sink.write", but both ways I

end up

Post by Jon Kleiser
with a completely empty file, zero bytes. Why is that happening?
/Jon
--
For other discussions, see https://groups.google.com/a/dartlang.org/
For HOWTO questions, visit http://stackoverflow.com/tags/dart
To file a bug report or feature request, go to

http://www.dartbug.com/new

Post by Jon Kleiser
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['Bob Nystrom' via Dart Misc]

Post by Jon Kleiser
Thanks, Istvan. Yes, putting "await" in front of "new File" looks like
it's the way to go. I just have to figure out a nice way to do the rest of
the printing, unless I shall give the total content as one big string to
'writeAsString'.

Note that File also supports synchronous versions of most of its methods.
If you don't need the asynchrony, I would recommend using the sync ones.
So, in this case, you can just use writeAsStringSync()
<https://api.dartlang.org/stable/1.22.1/dart-io/File/writeAsStringSync.html>
.

Cheers!

– bob

Post by Jon Kleiser
/Jon

Post by Istvan Soos
Hi Jon,
It might be possible that you are starting an async IO operation and
your program exits before it gets done. The following code should
import 'dart:io';
main() async {
await new File('output.txt').writeAsString('content');
}
https://www.dartlang.org/articles/dart-vm/io
Hope it helps.
Istvan

Post by Jon Kleiser
Hi,
I want to write some text to a file, and I have tried both methods

given at

Post by Jon Kleiser
https://api.dartlang.org/stable/1.22.1/dart-io/File-class.html, both

the one

Post by Jon Kleiser
using "writeAsString" and the one using "sink.write", but both ways I

end up

Post by Jon Kleiser
with a completely empty file, zero bytes. Why is that happening?
/Jon
--
For other discussions, see https://groups.google.com/a/dartlang.org/
For HOWTO questions, visit http://stackoverflow.com/tags/dart
To file a bug report or feature request, go to

http://www.dartbug.com/new

Post by Jon Kleiser
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[Jon Kleiser]

Thanks, all of you. I ended up with this:

var randAccFile = new File(filename).openSync(mode:
FileMode.WRITE_ONLY);
randAccFile.writeStringSync("label\n");
args.forEach((word) {
randAccFile.writeStringSync("$word\n");
});
randAccFile.closeSync();

/Jon

Post by 'Bob Nystrom' via Dart Misc

Post by Jon Kleiser
Thanks, Istvan. Yes, putting "await" in front of "new File" looks like
it's the way to go. I just have to figure out a nice way to do the rest of
the printing, unless I shall give the total content as one big string to
'writeAsString'.

Note that File also supports synchronous versions of most of its methods.
If you don't need the asynchrony, I would recommend using the sync ones.
So, in this case, you can just use writeAsStringSync()
<https://api.dartlang.org/stable/1.22.1/dart-io/File/writeAsStringSync.html>
.
Cheers!
– bob

Post by Jon Kleiser
/Jon

Post by Istvan Soos
Hi Jon,
It might be possible that you are starting an async IO operation and
your program exits before it gets done. The following code should
import 'dart:io';
main() async {
await new File('output.txt').writeAsString('content');
}
https://www.dartlang.org/articles/dart-vm/io
Hope it helps.
Istvan

Post by Jon Kleiser
Hi,
I want to write some text to a file, and I have tried both methods

given at

Post by Jon Kleiser
https://api.dartlang.org/stable/1.22.1/dart-io/File-class.html, both

the one

Post by Jon Kleiser
using "writeAsString" and the one using "sink.write", but both ways I

end up

Post by Jon Kleiser
with a completely empty file, zero bytes. Why is that happening?
/Jon
--
For other discussions, see https://groups.google.com/a/dartlang.org/
For HOWTO questions, visit http://stackoverflow.com/tags/dart
To file a bug report or feature request, go to

http://www.dartbug.com/new

Post by Jon Kleiser
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