CODEWITHSUNDEEP
sqliteperldbi
Loris
Loris

Reputation: 101

Perl make a SELECT query and return array of objects

I want to make a query to a sqlite database and return an array of objects.

I'm creating a telegram bot and i have to store the date of last message per user_id, because telegram API returns messages i've already read. So i've created a sqlite db with two tables: users and messages; users contains all the user_id and username; messages contains the last message_id i've read.

I've done this function, it works but it isn't performing very well because it has to recreate the entire array of objects (fetchrow_hashref).

sub sqlLiteSelect {
    my ($db,$table,$columnsRef,$where,$others) = @_;
    my $columns = join(', ', @{ $columnsRef });
    $others ||= '';
    my $query = "select ${columns} from ${table} ${where}${others}";
    my $obj = $db->prepare($query);
    my $ret = $obj->execute() or die $DBI::errstr;
    my @array = ();
    while(my $row = $obj->fetchrow_hashref) {
        my $tmp = {};
        foreach my $column (@{ $columnsRef }) {
            $tmp->{$column} = $row->{$column};
        }
        push @array, $tmp;
    }
    return @array;
}

my @columns  = ('user_id','first_name','username','type');
my $where = ' where user_id in (1,2)';
my @result = sqlLiteSelect($db,'users',\@columns,$where,'');
foreach my $row (@result) {
    print "user_id=$row->{user_id}, username=$row->{username}\n";
}

I expect my select to return an array of object without recreate it everytime.

Upvotes: 0

Views: 1657

Answers (1)

vanHoesel
vanHoesel

Reputation: 954

my ($user_id, $first_name, $username, $type);

my $sql = q{
SELECT user_id, first_name, username, type
  FROM users
 WHERE user_id IN (1,2)
};

my $sth = $db->prepare($sql);
$sth->execute or die $DBI::errstr;
$sth->bind_columns(\$user_id, \$first_name, \$username, \$type);

while ($sth->fetch) {
    print "$user_id, $username\n";
}

read the documentation https://metacpan.org/pod/DBI#bind_columns

Upvotes: 2

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