Perl dancer error execute method undefined - sqlite

Question

I was trying to make a website using perl dancer, below is my code. It seems to be correct but the page keeps loading and never enters the values in the database. When I cancel the page I get an error stating "request to POST /appform crashed: Can't call method "execute" on an undefined value". I can't figured out whats wrong in the code. If you have any other code please mention.
I am using SQLite for database.
There is a database campus.dband I am inserting the value in student table.
post '/appform' => sub {
my $q = CGI ->new;
my $name = $q->param ("firstname");
my $password = $q->param("password");
my $mobile_no = $q->param("mobile");
my $gender = $q->param("gender");
my $email = $q->param("email");
my $address = $q->param("address");
my $sslc = $q->param("SSLC");
my $hsc = $q->param("HSC");
my $cgpa = $q->param("cgpa");
my $languages = $q->param("lang");
my $internships = $q->param("intern");
my $preferred_loc = $q->param("country");
my $sql = "insert into student(name,mobile_no,gender,email,address,sslc,hsc,cgpa,languages,internships,preferred_loc,password,applied_job,company_applied) values ('?','?','?','?','?','?','?','?','?','?','?','?','?','?');";
my $sth = database->prepare($sql);
$sth->execute($name,$mobile_no,$gender,$email,$address,$sslc,$hsc,$cgpa,$languages,$internships,$preferred_loc,$password) or die $sth->errstr;
#$sth->execute();
$sth-> finish;
set_flash('New entry posted!');
redirect '/';
};

Answer 1

You're using the database keyword to get a database handle. I'm guessing that's coming from Dancer2::Plugin::Database (it would be useful if you could include information like this in your question).
The error says that you're calling execute() on an undefined value. You're calling execute() on the variable $sth. So $sth is undefined. You get $sth by calling prepare() on the database handle returned from database(). So it looks like the prepare() call is failing. You should check the return value from that call and throw an error if it fails.
The most common reason for prepare() to fail is that you're trying to compile an SQL statement that contains an error. I can't see any obvious error in your SQL, but it's worth checking it by running it manually against your database.
I see you're using bind params in your SQL statement. That's a great idea, but please note that you don't need to quote the question marks in your SQL - the database driver will handle that for you. I don't think that's what is causing your problem though.
I also see that you're using CGI.pm inside your Dancer app to get the request parameters. To be honest, I'm slightly surprised that it works - but it's a terrible idea. Dancer has its own keywords that will give you this information. Look at query_parameters(), body_parameters() and route_parameters() in the Dancer documentation.

Answer 2

In addition to the points made already, that your DBI prepare() call is probably failing (add error-checking to see why, e.g. my $sth = database->prepare('...') or die "DB error: " . database->errstr) and that you're using CGI.pm within a Dancer app (... don't do that, I'm surprised it would work at all - look at the Dancer documentation for how to access the params your app was sent), look also at the quick_insert convenience method provided by Dancer::Plugin::Database / Dancer2::Plugin::Database so that you don't have to write that SQL INSERT statement at all.