perl dancer tips


perl cpan dancer

Dancer2

  1. Return to previous page after login (return_url)
    • cpanm install Dancer2::Plugin::Auth::Tiny
    • In config.yml plugin can be configured for the logged_in_key (optional). Indentation is very important. Set logged_in_key value (logged_in) as true in POST ‘/login’ route if username and password matches. 
      # for Dancer2::Plugin::Auth::Tiny
  Auth::Tiny:
    logged_in_key: logged_in
    • In the lib/project.pm 
      # login
get '/login' => sub {
  # put 'return_url' in a hidden form field  
  #print "================>Thsi is the return url" . params->{'return_url'} . "\n";
  template 'login.tt' => { 
  return_url => params->{'return_url'},
  };
  }; 
post '/login' => sub {
  my $err;
  if ( request->method() eq "POST" ) {
         # process form input
         if ( params->{'username'} ne setting('username') ) {
                 $err = "Invalid username";
         }
         elsif ( params->{'password'} ne setting('password') ) {
                 $err = "Invalid password";
         }
         else {
                 session 'logged_in' => true;
                 set_flash('You are logged in.');
                 #print "================>Thsi is the return url" . params->{'return_url'} . "\n";
                 return redirect params->{return_url} || '/'; # return to previous page prior to login
                 #return redirect '/';
         }
 } 
 # display login form
 template 'login.tt', {
         'err' => $err,
 };
 };
    • In views/login.tt (The “return_url” parameter is needed) 
      [% INCLUDE header.tt %]
<ul class=entries>
<h2>Login</h2>
[% IF err %]<p class=error><strong>Error:</strong> [% err %][% END %]
<form action="[% login_url %]" method=post>
<dl>
<dt>Username: <input type=text name=username><br><br>
<dt>Password: <input type=password name=password><br><br>
<!--<dt>Return: is [% return_url %]-->
<input type=hidden name=return_url value=[% return_url %]><br><br><!-- return to pre login page -->
<dd><input type=submit value=Login>
</dl>
</form>
</ul>
    • protected route requiring login. In lib/project.pm (The “needs login” is needed) 
      get '/private' => needs login => sub { your code here };
  2. encrypted password stored in config.yml
    • cpanm Dancer2::Plugin::Auth::Extensible
    • In config.yml plugin can be configured. Indentation is important. 
      plugins:
    Auth::Extensible:
        realms:
            config:
                provider: Config
                users:
                    - user: dave
                      pass: supersecret
                      roles:
                        - Developer
                        - Manager
                        - BeerDrinker
                    - user: bob
                      pass: '{SSHA512}2QOSf9rnEYz8gAJBBFdAK/xEwrYILmRUraJU0WaTsMvMywfnJO5aM38EDSDPZhusjof1PDtcpWbn6oCaX+WLh8vNXeU='
                      roles:
                        - Tester
    • Generate the salted hash and paste the output in the pass: above 
      dancer2-generate-crypted-password
    • In the lib/myapp.pm add the login code 
      use Dancer2;
use Dancer2::Plugin::Auth::Extensible;
get '/' => require_login  sub {
template 'index' => { 'title' => 'userauth' };
};
  3. plain text password in mysql db 
    • cpanm Dancer2::Plugin::Database
cpanm Dancer2::Plugin::Auth::Extensible
    • In config.yml plugin can be configured. Indentation is important. 
      plugins:
  Database:
    connections:
      foo:
        driver: 'mysql'
        database: 'userauth'
        host: 'localhost'
        port: 3306
        username: 'root'
        password: 'secret'
        connection_check_threshold: 10
        dbi_params:
          RaiseError: 1
          AutoCommit: 1
        on_connect_do: ["SET NAMES 'utf8'", "SET CHARACTER SET 'utf8'" ]
        log_queries: 1
        #handle_class: 'My::Super::Sexy::Database::Handle'

  Auth::Extensible:
    realms:
      users:
        provider: 'Database'
        db_connection_name: 'foo'
        disable_roles: 1
        users_table: 'active_users'
        roles_table: 'roles'
        user_roles_table: 'user_roles'
        users_id_column: 'id'
        users_username_column: 'username'
        users_password_column: 'password'
        roles_id_column: 'id'
        roles_role_column: 'role'
        user_roles_user_id_column: 'user_id'
        user_roles_role_id_column: 'roles_id'
    • Create mysql schema 
      CREATE TABLE users (id INTEGER PRIMARY KEY AUTO_INCREMENT,username VARCHAR(32) NOT NULL UNIQUE,password VARCHAR(40) NOT NULL,disabled TIMESTAMP NULL );
CREATE TABLE roles (id INTEGER AUTO_INCREMENT PRIMARY KEY,role VARCHAR(32) NOT NULL);
CREATE TABLE user_roles (user_id  INTEGER  NOT NULL,role_id  INTEGER  NOT NULL,UNIQUE KEY user_role (user_id, role_id));
CREATE VIEW active_users (id, username, password) AS SELECT id, username, password FROM users WHERE disabled IS NULL;
INSERT INTO users ( username, password, disabled ) VALUES  ( 'Alice', 'test', null), ( 'Bob', 'test', '2017-10-01 10:10:10');
    • In the lib/myapp.pm add the login code 
      use Dancer2;
use Dancer2::Plugin::Database;
use Dancer2::Plugin::Auth::Extensible;

get '/' => require_login  sub {
template 'index' => { 'title' => 'userauth' };
};
  4. Encrypt password in mysql db
    • Install below modules 
      cpanm Dancer2;
cpanm Dancer2::Plugin::Passphrase; #for crypt salt hash password
cpanm Data::Dumper; #for debugging
cpanm Dancer2::Plugin::Database;  #for db connections.
cpanm Dancer2::Plugin::Auth::Tiny;  #for "needs login" in protected routes
    • In config.yml plugin can be configured for the logged_in_key (optional). Indentation is very important. Set logged_in_key value (logged_in) as true in POST ‘/login’ route if username and password matches. 
      plugins:
  Database:
    connections:
      foo:
        driver: 'mysql'
        database: 'userauth'
        host: 'localhost'
        port: 3306
        username: 'root'
        password: 'secret'
        connection_check_threshold: 10
        dbi_params:
          RaiseError: 1
          AutoCommit: 1
        on_connect_do: ["SET NAMES 'utf8'", "SET CHARACTER SET 'utf8'" ]
        log_queries: 1
        #handle_class: 'My::Super::Sexy::Database::Handle'

  Auth::Tiny:
        logged_in_key: 'logged_in'
    • Create mysql schema 
      CREATE TABLE users (id INTEGER PRIMARY KEY AUTO_INCREMENT,username VARCHAR(32) NOT NULL UNIQUE,password VARCHAR(40) NOT NULL,disabled TIMESTAMP NULL );
CREATE TABLE roles (id INTEGER AUTO_INCREMENT PRIMARY KEY,role VARCHAR(32) NOT NULL);
CREATE TABLE user_roles (user_id  INTEGER  NOT NULL,role_id  INTEGER  NOT NULL,UNIQUE KEY user_role (user_id, role_id));
CREATE VIEW active_users (id, username, password) AS SELECT id, username, password FROM users WHERE disabled IS NULL;
INSERT INTO users ( username, password, disabled ) VALUES  ( 'Alice', 'test', null), ( 'Bob', 'test', '2017-10-01 10:10:10');
    • The lib/userauth.pm file 
      package userauth;
use Dancer2;
use Dancer2::Plugin::Passphrase; #for crypt salt hash password

use Data::Dumper;
use Dancer2::Plugin::Database;  #for db connections.
#use Dancer2::Plugin::Auth::Extensible;  #for automatic /login route etc
use Dancer2::Plugin::Auth::Tiny;  #for "needs login" in protected routes

sub set_flash {
    my $message = shift;

    session flash => $message;
}

hook before_template => sub {
       my $tokens = shift;

       $tokens->{'css_url'} = request->base . 'css/style.css';
       $tokens->{'login_url'} = uri_for('/login');
       $tokens->{'logout_url'} = uri_for('/logout');
};

# mysql db settings.
sub connect_db {
  my $db = DBI->connect('DBI:mysql:userauth', 'root', 'secret') or
     die $DBI::errstr;

  return $db;
}

# subroutine for fetching password from db.
sub fetch_password_from_db {
    my ($username,$password) = @_;
    my $db = connect_db();
    my $sqltransaction = 'select username,password from users where username=(?)';
    my $sthtransaction = $db->prepare($sqltransaction) or die $db->errstr;
    $sthtransaction->execute($username) or die $sthtransaction->errstr;

    my $sqlresultuserrow = $sthtransaction->fetchrow_hashref;

    return $sqlresultuserrow; 
};

# login
get '/login' => sub {
       # put 'return_url' in a hidden form field  
       template 'login.tt' => { 
       return_url => params->{'return_url'},
       };
};    

post '/login' => sub {
      my $err;
      #username and password provided by login form
      my $username = param('username');
      my $password = param('password');
      #fetch values from db
      my $saved_userpass = fetch_password_from_db($username,$password);
      my $stored_username_string = $saved_userpass->{username};
      my $stored_rfc_2307_string = $saved_userpass->{password};

      if ( params->{'username'} ne ( $stored_username_string ) ) {

      #username is ok.
      $err = "Invalid username";

      }

      elsif ( passphrase( param('password') )->matches( $stored_rfc_2307_string ) ) {
      # Passphrase matches!
      print "\nPassphrase matches ========================>>>>>>\n";

      session 'logged_in' => true;
      set_flash('You are logged in.');

      redirect params->{'return_url'} || '/'; # return to previous page prior to login

    }
      else {
        print "\nPassphrase does not match ========================>>>>>>\n";
        $err = "Invalid password";
    }
};

#user registeration form.
get '/register' => sub {

    template 'register' => { 
    'title' => 'registeration form',
    register_user_url => uri_for('/register'),
    };
    };

#route for inserting in db.
post '/register' => sub {

    my $username = param('username');
    my $password = passphrase(param('password'))->generate(
    {
        algorithm => 'Bcrypt',
        Bcrypt   => {
            cost => 04,
        }
    }
    );

    # $password is now a hashed password object
    save_user_in_db( $username, $password->rfc2307 );

    #template registered => { success => 1 };
};

# save user and password (crypt salted hash) in db.
sub save_user_in_db {
    my ($username, $password) = @_;
    my $db = connect_db();
    my $sqltransaction = 'insert into users(username, password) values(?, ?)';
    my $sthtransaction = $db->prepare($sqltransaction) or die $db->errstr;
    $sthtransaction->execute($username, $password) or die $sthtransaction->errstr;
};

get '/private' => needs login => sub {
    template 'index' => { 'title' => 'userauth' };
};

get '/logout' => sub {
       context->destroy_session;
       set_flash('You are logged out.');
       redirect '/';
};

get '/generate_new_password' => sub {
    return passphrase->generate_random;
};

true;
    • views/register.tt 
      <h2>Register</h2>
[% IF err %]<p class=error><strong>Error:</strong> [% err %][% END %]
<form action="[% register_user_url %]" method=post>
<dl>
<dt>Username:
<dd><input type=text name=username>
<dt>Password:
<dd><input type=password name=password>
<dd><input type=submit value=Login>
</dl>
</form>
    • views/login.tt 
      [% IF vars.login_failed %]
<div class="alert alert-danger">
<strong>Login Failed</strong> Try again
<button type="button" class="close" data-dismiss="alert" aria-label="Close">
<span aria-hidden="true">&times;</span>
</button>
</div>
[% END %]

<form method = "post" lpformnum="1" class="form-signin">
<h2 class="form-signin-heading">Please sign in</h2>
<label for="username" class="sr-only">Username</label>
<input type="text" name="username" id="username" class="form-control" placeholder="User name" required autofocus>
<label for="password" class="sr-only">Password</label>
<input type="password" name="password" id="password" class="form-control" placeholder="Password" required>
<button class="btn btn-lg btn-primary btn-block" type="submit">Sign in</button>
<br>
<input type="hidden" name="return_url" value="[% return_url %]">
</form>
  5. fetchrow_array in lib/xxxxxx.pm
    • Select from mysqldb and get the resulting data as an array 
      # start festival data structure
my $sql4='SELECT feast,url,description FROM `festivals` WHERE `date` = CURDATE()';
my $sth4 = $db->prepare($sql4) or die $db->errstr;
$sth4->execute or die $sth4->errstr;
my $feast;
my $url;
my $description;
($feast, $url,$description) = $sth4->fetchrow_array();
$sth4->finish;
my ($feastnameRef,$urlRef,$descriptionRef) = ($feast,$url,$description);
# end festival data structure


template 'query5.tt', {
'countryname' => $countrynameRef,
'statename' => $statenameRef,
'cityname' => $citynameRef,
'churchid' => $churchidRef,
'feastname' => $feastnameRef,
'feastdescription' => $descriptionRef,
'url' => $urlRef,
'title' => 'Churches of India',
'request.uri_base' => 'http://localhost/',
'Testing'   => "This is text to test to make sure this will come through", # to test, use this like <% Testing %> on your template page
};
  6. fetchall_href in lib/xxxxxx.pm
    • Select from mysqldb and get the resulting data as a hash 
      my $db = connect_db();
my $sql='SELECT country_id,country_name FROM country';
my $sth = $db->prepare($sql) or die $db->errstr;
$sth->execute or die $sth->errstr;
my $countrynameRef = $sth->fetchall_hashref('country_name');

template 'query5.tt', {
'countryname' => $countrynameRef,
'statename' => $statenameRef,
'cityname' => $citynameRef,
'churchid' => $churchidRef,
'feastname' => $feastnameRef,
'feastdescription' => $descriptionRef,
'url' => $urlRef,
'title' => 'Churches of India',
'request.uri_base' => 'http://localhost/',
'Testing'   => "This is text to test to make sure this will come through", # to test, use this like <% Testing %> on your template page
 };
    • Another example of Select from mysqldb and get the resulting data as a hash 
      get '/testarray' => sub {
my $db = connect_db();
my $sql='SELECT state_id,state_name FROM state';
my $sth = $db->prepare($sql) or die $db->errstr;
$sth->execute or die $sth->errstr;

# build data structure
my $id;
my $name;
my %data;
while (($id, $name) = $sth->fetchrow_array()) {
$data{$id} = {
id => $id,
name => $name
}
}
$sth->finish;

# build city data structure
my $sql1='SELECT city_id,city_name FROM city';
my $sth1 = $db->prepare($sql1) or die $db->errstr;
$sth1->execute or die $sth1->errstr;

my $id1;
my $name1;
my %data1;
while (($id, $name) = $sth1->fetchrow_array()) {
$data1{$id} = {
cityid => $id,
cityname => $name
}
}
$sth1->finish;
template 'testarray.tt' => { 'title' => 'church_timing',
'data' => \%data,
'data1' => \%data1
};
};