Re: Using Tie::IxHash to keep database query keys/values in order

"I want to keep the keys/values in the same order for every array element in an AoH ref."

You just cant do that. You could instruct data dumper to PRINT them in sorted order (local $Data::Dumper::Sortkeys=1;), or you could program your own print loop to print them in a certain order,

use strict; use warnings; 
my $data=

[
    {
        'lastname'  => 'Smith',
        'city'      => 'Chicago',
        'state'     => 'IL',
        'firstname' => 'Jim'
    },
    {
        'city'      => 'Cleveland',
        'state'     => 'OH',
        'firstname' => 'Susan',
        'lastname'  => 'Jones'
    },
    {
        'state'     => 'FL',
        'lastname'  => 'Waters',
        'firstname' => 'Sam',
        'city'      => 'Miami'
    }
];

my @order=qw/firstname lastname city state/; 
my $rowct=0; 
for my $row (@$data) { 
  printf "%5i \n",$rowct++; 
  for my $ordername (@order) { 
    printf " %20s %-20s \n",$ordername,$row->{$ordername}; 
    }
  }
[download]

but you cannot make perl keep them in any sort of "order" than the one it decides on.

Comment on Re: Using Tie::IxHash to keep database query keys/values in order Select or Download Code

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Re^2: Using Tie::IxHash to keep database query keys/values in order by huck (Prior) on Feb 15, 2017 at 23:00 UTC
As an interesting alternative to the qw/.../ you may find some interesting info about getting the field names from the sql request at Re: Field names from DBI? . that would allow you to specify the order via the SELECT statement, but it a two step setup described in setting up and executing the SQL. YMMV	[reply]
Re^2: Using Tie::IxHash to keep database query keys/values in order by bradcathey (Prior) on Feb 15, 2017 at 23:09 UTC
So Data::Dumper is throwing me off and Tie::IxHash just might be keeping them in order as advertised. I'll write a loop to check that. Thanks for the lesson in D::D —Brad "The important work of moving the world forward does not wait to be done by perfect men." George Eliot	[reply]
Re^3: Using Tie::IxHash to keep database query keys/values in order by AnomalousMonk (Archbishop) on Feb 16, 2017 at 00:52 UTC
So Data::Dumper is throwing me off and Tie::IxHash just might be keeping them in order as advertised. It's unlikely that Data::Dumper has anything to do with it. As others have written, my guess would be that `selectall_arrayref()` is returning a reference to an entirely separate hash it generates and populates internally. After all, how would this function "know" that you want it to use the hash referred to by `$data` to populate with the data it is to return? I can't use Tie::IxHash to produce an example ATM, but consider: `c:\@Work\Perl\monks>perl -wMstrict -le "package Foo::Bar { sub TIEHASH {} } ;; my $data = {}; tie %$data, 'Foo::Bar'; print $data; ;; $data = return_anon_hash_ref(); print $data; ;; use Data::Dumper; print Dumper $data; ;; sub return_anon_hash_ref { return { 'sorry' => 'charley' }; } " HASH(0x3bd06c) HASH(0x3bd15c) $VAR1 = { 'sorry' => 'charley' };` [download] Note that the addresses of `$data` in the two print statements are different, as are the contents of the referents. Nothing you do with `Data::Dumper` is going to change this. Bottom line: Write your own data display loop or routine and use whatever explicit key order you want. Give a man a fish: `<%-{-{-{-<`	[reply] [d/l] [select]