Modifying Records Part 2

I told you all that after we get started, it just makes sense. Now onto the third part of editing.......

elsif ($form{'action'} eq "edit_three") {
    &edit_three;
}

&edit_three.... how ingenious of a name.

sub edit_three {
    &header("Edit Record");

The header part of the page. We are sending it the title "Edit Record"

    print qq~
    <CENTER><TABLE border=1 bgcolor="#FFFFFF" cellpadding=3 cellspacing=0>
    <TR bgcolor="#C0C0C0"><TD>
    <CENTER>
    <FORM METHOD=POST>
    <INPUT TYPE="hidden" NAME="action" VALUE="edit_four">
    <INPUT TYPE="hidden" NAME="key" VALUE="$form{'key'}">~;

This part was mainly just simple html, but notice the two hidden fields. The first one is our infamous action field, with a value of edit_four (guess what the next sub will be named :-) ), and the other hidden field is 'key', with the value of $form{'key'} in it. $form{'key'} is the ID number, or whatever you set $db_key to be as the record identifier.

    my (%result) = &get_record($form{'key'});

Into the hash %result goes the returned value of &get_record after feeding into it the value of $form{'key'}, the database entry identifier.

Since I did not explain &get_record in the adding record section of this tutorial, I promised to explain it here.

sub get_record {
     my ($exist) = 0;

Set this my variable to a null value

     my ($key) = shift;

This my variable will now have the data sent to it (the database entry identifier) as its value.

    open(DATA, $file);

Here we open the database file with a handle of DATA

    while (<DATA>) {

As long as DATA has a value and did not reach the end of file mark yet, this loop will repeat.

        (/^\s*$/) and next; # Looks for blank lines and skip them.

Just as the comment tag states, here we look for blank lines and skip them, going to the next line.

        chomp $_;

$_ has a newline attached at the end, so here we ourselves of it.

        @record = &grab_data($_);

Here we do our usual line processing. &grab_data splits the line into an array, @record;

        %dat = &process_record(@record);

&process_record in turn changes @record to a hash for easy use.

        if ($dat{$db_key} eq $key) {
            $exist = 1;
            last;
        }

If the database link identifier is equal to the $key we are requesting, $exist is set to a non-null value, and we break out of the while loop.

    }

End of While Loop

    close (DATA);

Here we close our read-only copy of DATA.

    $exist ? return (%dat) : return;

Here comes our new friend, the ternary operator, making yet another appearance. If $exist has a non-null value, the contents of our hash %dat is returned. Otherwise, we return no value at all.

}

End of get_record