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Question : File Update - Expert pitonyak please note.
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Hi Experts,
I have a flat file with records in
1000^email^platform^detail^status
format. pitonyak and others helped me set up the script to generate the tracking number. now my requirement is:
I have managed to get the data back into a form for update, now, when I click on update, I need a script which will scan my database, look for the track number, and update the changes, and if the status has changed, send a email.
-Help , urgent requirement.
PS: I am a newbee to perl.
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Answer : File Update - Expert pitonyak please note.
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OK, here is some code to perform the update. It aint quick and it aint robust. Shoot me a copy of what you finally use.
[email protected]
#
# This is not a production safe routine.
# Some issues it will not handle.
# This will fail if the file does not exist.
# File locking is not implemented.
# This assumes that NO line is longer than $max_line_len
# No check is made that the status is really the correct length.
# I assume that you want a status longer than 10.
#
use IO::file;
use StrFmt;
use Fcntl ':flock'; # import LOCK_* constants
my $max_line_len = 100;
my $status_len = 10;
sub add_record
{
#
# You should probably add some error checking here
# verify that that all of these have values
# and see what happens when one of them is empty or something.
#
my ($file_name, $email, $platform, $detail, $status) = @_;
my $fh = new IO::File;
if ($fh->open("+<$file_name")) {
#
# This allows things to run in a mult-user system.
# but not implemented on my test system
#
#flock($fh, LOCK_EX); # LOCK_EX is probably 2
my $file_size = ($fh->stat())[7];
my $new_pos = $file_size - $max_line_len;
print "File Size = $file_size\n";
my $next_num = 1;
if ($file_size > 0) {
$fh->seek($new_pos, 0) if $new_pos > 0;
while (<$fh>) {
my ($tmp) = /^\s*(\d+)/;
$next_num = $tmp if defined($tmp);
}
}
++$next_num;
$fh->seek(0, 2);
$status = StrFmt::right_fmt($status_len, $status); # padd on the left
my $out_line = join('^', ($next_num, $email, $platform, $detail, $status));
print $fh "\n$out_line";
print "$out_line\n";
# but not implemented on my test system
#flock($fh, LOCK_UN); # LOCK_UN is probably 8
$fh->close();
} else {
print "Unable to open file $file_name because $!\n";
}
undef $fh;
}
sub update_record
{
#
# You should probably add some error checking here
# verify that that all of these have values
# and see what happens when one of them is empty or something.
#
my ($file_name, $num, $new_status) = @_;
my $fh = new IO::File;
if ($fh->open("+<$file_name")) {
#
# This allows things to run in a mult-user system.
#
# but not implemented on my test system
#flock($fh, LOCK_EX); # LOCK_EX is probably 2
#
# This is really ineffecient. I do a linear search
# A better solution may be to perform a binary search
# if the file becomes larger.
#
my $cur_pos = $fh->tell();
my $line = $fh->getline();
my $done = 0;
my $this_num = $num - 1;
while (defined($line) && !$fh->error() && !$done) {
chomp($line);
$this_num = (split /\^/ , $line)[0];
if ($this_num == $num) {
print $line."\n";
$done = 1;
} else {
$cur_pos = $fh->tell();
$line = $fh->getline();
}
}
if ($this_num != $num) {
print "WARNING, unable to find record $num\n";
} else {
my $status_loc = $cur_pos + length($line) - $status_len;
$fh->seek($status_loc, 0);
if ($fh->tell() != $status_loc) {
print "??Bad error, say something\n";
} else {
#
# A smarter person would verify the length of the satus first.
# if (length((split /\^/ , $line)[4]) != $status_len) {
# either print to this length or generate an error
# }
#
my $status = StrFmt::right_fmt($status_len, $new_status); # padd on the left
print $fh $status;
}
}
# but not implemented on my test system
#flock($fh, LOCK_UN); # LOCK_UN is probably 8
$fh->close();
} else {
print "Unable to open file $file_name because $!\n";
}
undef $fh;
}
add_record('tst', 'email', 'OS/2', 'this is a test', 'status');
update_record('tst', 35, 'new status');
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