Lewick, Taylor wrote:
> Hi all, I have been using perl for sometime for CGI scripts, but have
> always used the print content-type:html version of doing things.
>
> I would like to learn a better way with the CGI module, but when I
> read the docs I find it pretty easy to get confused as to whether I
> should use the object oriented method, or the functional method.
Either is fine IMO. The function method requires you to import the correct
symbols, which can be a bit tricky.
>
> Also, because my script is a cgi form that gets some of the select
> fields from a mysql database, I am not sure how to convert that over.
> I don't know how I would make the select field work the same.
>
> I am not asking for someone to rewrite my project, merely provide me
> with some examples of how they would write the same code using the cgi
> module so I can figure this out a bit better...
>
> On my form, I am querying a database for a list of names and loading
> them into a select box. But I found out people want to enter more
> than one name at a time, so I loop through 15 times, and they can
> select up to 15 names... They select a name, but I store the name's
> id, so it acts as a lookup field...
>
> Here is how I do this now..
> #Connect to database
> print "<table>\n";
> for (1..15) {
> print "<td nowrap>\n";
> $query_teams=("select id, name from teams");
> $sth = $dbh->prepare($query_teams);
> $sth->execute();
> $sth->bind_columns(\$id, \$name);
> print "<select name='away_team$_'>"; #$_ traps which pass of the loop
> we are in i.e., 3rd pass, 4th pass, etc
> print "<option value='0'></option>\n";
> while($sth->fetch()) {
> print "<option value='$id'>$name</option>\n";
> }
> print "</select>\n";
> $sth->finish();
> print "</td>\n";
> } #end for loop
> print "</table>\n";
> #disconnect from database
>
> How would I start to convert this with the CGI module. My problems
> thus far are on a popup menu, how do I specify the field variable
> that I grab is the ID, while the displayed value is another, and how
> can I say the first value should be 0, in case they do not enter
> anything?
You're querying the database 15 times; I definitely wouldn't do that.
I ususally grab all the rows into an arrayref using something like this:
my $rows = $dbh->selectall_arrayref('select id, name from teams');
This handles all the DBI calls one one swoop.
For the CGI module's popup_menu, you need two things:
1) a list of values for the <option> elements, and
2) a hash of value => description pairs for the labels
Here's how to get the labels hash from the rows fetched above:
my %labels = ( 0 => '', map @$_, @$rows );
You can extract the value list from the hash keys:
my @values = sort { $a <=> $b } keys %labels;
Now you can generate the table by using CGI's routines like this (OO style):
print $q->start_table,
$q->start_Tr,
$q->td({ -nowrap => 'nowrap' }, [ map $q->popup_menu(
-name => "away_team$_",
-labels => \%labels,
-values => [EMAIL PROTECTED],
-default => '0',
), 1 .. 15 ]),
$q->end_Tr,
$q->end_table;
CGI let's you use start_xxx and end_xxx methods to generate just a start or
end tag.
If you pass an arrayref to a method like td(), CGI will generate multiple
elements, one for each entry in the array. This lets us generate all 15 <td>
elements in one call. Look in the CGI docs under "THE DISTRIBUTIVE PROPERTY
OF HTML SHORTCUTS"
The map() function generates a list of <select> objects.
HTH
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