write_file to_json in Dancer app

GertMT has asked for the wisdom of the Perl Monks concerning the following question:

I'm trying to create a little app that shows a list of files on a web-page to be commented on.
It seems all to work. The web-page is generated via reading the content of a directory. I'd like to parse the list of images to_json to use it in a form. However I can't seem to get this parsing right.

"error" : "write_file '' - sysopen: No such file or directory at /Users/test/mytest/lib/mytest.pm line 35.\n"

Maybe someone can give me a hint what I'm doing wrong?
Gert

package mytest;
use Dancer ':syntax';
use List::Util;
use File::Slurp qw(read_file write_file);
our $VERSION = '0.1';
set serializer => 'JSON';

get '/'        => sub {
    template 'index' => { photos => AoH_imagelist(), };
};

#---------------------------------------------------------------------
#
# function to read image-dir-gallery and create imagelist stored in Ao
+H
#
#---------------------------------------------------------------------
sub AoH_imagelist {
    my @photos;
    my $images_dir =
      Dancer::FileUtils::path( setting('appdir'), 'public/images/galle
+ry' );
    opendir( my $dh, $images_dir ) || die "can't opendir $images_dir: 
+$!";
    my @image_files = grep { $_ if /\.jpg$/i } readdir($dh);

    for my $i (@image_files) {
        push @photos, { file => "$i", caption => "" };
    }

    #-------v this doesn't work? --------#
    my $filename = config->{mytest}{json};
    my $json     = -e $filename ? read_file $filename : '{}';
    my $data     = \@photos;

    #my $data     = from_json $json;
    $data = { file => params->{file} , caption => params->{caption}, }
+;
    # description to be added
    write_file $filename, to_json($data);
    #-------^-----------------------------#

    return \@photos;
}
true;
[download]

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Replies are listed 'Best First'.
Re: write_file to_json in Dancer app by Corion (Patriarch) on Feb 04, 2014 at 16:35 UTC
The error message suggests to me that `$filename` is empty. Maybe you need to initialize it from a different place in your configuration? Does uploading work if you hardcode the value for `$filename` instead of using the configuration?	[reply] [d/l] [select]
Re^2: write_file to_json in Dancer app by GertMT (Hermit) on Feb 04, 2014 at 16:46 UTC
aha, yes, thanks. That does work. The file is updated if I refresh the browser. Well, with not much I'll have to admit but at least the modification time changes. So, I'm not there with the format but I should be able to work that out. Thanks!	[reply]
Re^3: write_file to_json in Dancer app by GertMT (Hermit) on Feb 05, 2014 at 11:06 UTC
updating the code between the comment lines to the code I mention below makes that the data is been written to a 'json' file. Not very clever code yet as the data gets overwritten every time you run the script but that is a separate issue. `#-------v this does work --------# my $filename = "testme.json"; my $json = -e $filename ? read_file $filename : '{}'; my $data = from_json $json; $data = \@photos; write_file $filename, to_json($data);` [download]	[reply] [d/l]