Checking JSON decoded params from Dancer

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

Hello Monks,
I have an issue where I am trying to check JSON decoded data from Dancer params. My module has something like this:


use strict;
use warnings;
use Dancer;
use JSON qw(decode_json);

my $foo_info = param('foo_info');
if ( !eval { decode_json($foo_info); 1 } )  {
    flash error => "Failed"
}

if ( !exists $foo_info->{foo_total}
    || !($foo_info->{foo_total} =~ m/^\$\d+\.\d{2}$/)) {
        error("Invalid or missing foo info");
        return 0;
}
[download]

And the errors that I am getting are:

Error decoding json data:
 malformed JSON string, neither tag, array, object, number, string or 
+atom, at character offset 0 (at the line I'm decoding the json)
request to POST /path/to/site crashed: Can't use string .. (json data 
+spit out here) as a HASH ref
[download]

So my problem may be 2 fold, but I do know I need help checking the values in the JSON 'foo_info' ..Any insight is greatly appreciated :)

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Re: Checking JSON decoded params from Dancer by Corion (Patriarch) on Jul 11, 2014 at 16:55 UTC
`decode_json` is a function. It returns the data structure and does not modify its argument in place. You might want: `my $foo; my $ok= eval { $foo= decode_json( $foo_info ); 1; }; if( ! $ok ) { my $err= $@; flash error => "Failed"; warn "JSON Decoder got '$err'"; }; # Now we have the decoded data structure in $foo warn Dumper $foo;` [download]	[reply] [d/l] [select]
Re^2: Checking JSON decoded params from Dancer by PerlSufi (Friar) on Jul 11, 2014 at 17:39 UTC
Thanks Corion- good to know. I am still trying to figure out how to correctly parse the data to see if I have the correct field and value in the json..	[reply]
Re: Checking JSON decoded params from Dancer by roboticus (Chancellor) on Jul 11, 2014 at 16:55 UTC
PerlSufi: ~~The string `foo_info` doesn't look much like JSON...~~ Update: My mistake--I misread the code. ...roboticus When your only tool is a hammer, all problems look like your thumb.	[reply] [d/l]