Returning columns with SQL::Statement error

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

Hello, I am sorry for bothering you but trying to execute the paradigm of SQL::Statement::Structure on a Strawberry perl v5.21.1 I had the following error.

Can't call method "name" on unblessed reference
The code is the following:

use SQL::Statement;
use Data::Dumper;
my $sql    = "SELECT a,aa FROM b JOIN c WHERE c=? AND e=7 ORDER BY f D
+ESC LIMIT 5,2";
my $parser = SQL::Parser->new();
$parser->{RaiseError}=1;
$parser->{PrintError}=0;
# $parser->parse("LOAD 'MyLib::MySyntax' ");
my $stmt = SQL::Statement->new($sql,$parser);
printf "Command             %s\n",$stmt->command;
printf "Num of Placeholders %s\n",scalar $stmt->params;

printf "Tables              %s\n",join( ',', map {$_->name} $stmt->tab
+les() );
printf "Where operator      %s\n",join( ',', $stmt->where->op() );
printf "Limit               %s\n",$stmt->limit();
printf "Offset              %s\n",$stmt->offset();

printf "Columns             %s\n",join( ',', map {$_->name} $stmt->col
+umn_defs() );
[download]

Output

Can't call method "name" on unblessed reference at c:\Users\PasvantidisR\Documents\scripts\perl\test_sql_statement.pl line 17.

Command SELECT
Num of Placeholders 1
Tables b,c
Where operator AND
Limit 2
Offset 5

Can you please help? Thank you Lalakis Oeisagwmenos

Comment on Returning columns with SQL::Statement error Download Code

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Re: Returning columns with SQL::Statement error by poj (Abbot) on Jan 19, 2018 at 16:40 UTC
I see your bug report has been answered but a work around in this case would be `printf "Columns %s\n",join ',', map { $_->{'value'} } @{$s +tmt->column_defs()};` [download] poj	[reply] [d/l]
Re^2: Returning columns with SQL::Statement error by LalakisOeisagwmenos (Novice) on Jan 22, 2018 at 11:17 UTC
YES! You are totaly correct. Thank you. I didn't thought I had to expand the return of $stmt->column_defs() to an array reference (a hash slice surrounding it with @{}) even though dumper was returning an array reference. What a stupid I was. And yes it is 'value' hash value. THANK YOU!!!	[reply]
Re: Returning columns with SQL::Statement error by thanos1983 (Parson) on Jan 19, 2018 at 16:24 UTC
Hello LalakisOeisagwmenos, Welcome to the Monastery. I do not run SQL on my OS but the error seems to be coming from line 17: `printf "Columns %s\n",join( ',', map {$_->name} $stmt->col +umn_defs() );` [download] Can you check if this method `name` is contained in? `print Dumper $stmt->column_defs();` [download] Always always use strict and warnings. Looking forward to your update, BR. Seeking for Perl wisdom...on the process of learning...not there...yet!	[reply] [d/l] [select]
Re^2: Returning columns with SQL::Statement error by LalakisOeisagwmenos (Novice) on Jan 22, 2018 at 11:09 UTC
Thank you for your reply. I have done so before to check my self too. It seems though that this method don't exist. But either don't exist value map{$_->value()} or trying to access it as a hash value map{$_->{value}} either quoted or not. It seems that the self is not blessed when the columns object is created. `$VAR1 = [ { 'type' => 'column', 'fullorg' => 'a', 'value' => 'a' }, { 'fullorg' => 'aa', 'type' => 'column', 'value' => 'aa' } ];` [download]	[reply] [d/l]
Re: Returning columns with SQL::Statement error by Anonymous Monk on Jan 19, 2018 at 21:27 UTC
Also, an old-fashioned `foreach` loop might be more-obvious than `map`. Use Data::Dumper so that you can see what `$stmt` consists of.	[reply]