How to checkin to foursquare via backend using PERL and PHP

Checking in to foursquare is more likely the same as posting a shout out, tweet or status in social network like facebook and twitter.

Foursquare follows authentication via OAuth and this post will teach you how to do it via back-end using PERL and PHP.

I assume you already read my post on how to Login to foursquare via back-end in PERL. You should be able to understand it first to proceed with authentication and do the check-in in users behalf.

Just follow the simple steps for your implementation.

1. You must have a Client ID and the Callback URL. If you don't have yet, create one by going to foursquare developers link - http://developer.foursquare.com/

2. To register a new consumer, click the "Manage OAuthConsumers" link or go to OAuth page - https://foursquare.com/oauth/

3. Enter your Application Name, Application Website, and Callback URL. Please take note that your Callback URL will be your Redirect URI.

4. After successful registration, Client ID and Client Secret will be generated.

5. What we need from now is the Client ID and once we have it, we can now start the coding part.

6. First thing we have to do is to login to users account via back-end. Please see post - Login to foursquare via back-end in PERL

7. After successful login, next step is to authenticate your application. To authenticate your app, you should pass a Client ID and your Callback URL that was registered from Consumer Registration.

$client_id = '<your client id>';
$redirect_uri = '<your callback url>';

$response = $lwpua->get("https://foursquare.com/oauth2/authenticate?client_id=$client_id&response_type=code&display=touch&redirect_uri=$redirect_uri", @header);

$form_data = $response->content;
$form_data =~ s/\n//g;

8. If this is the first time you authenticate your app, return page will be asking users permission to "Allow" the application to access account details and transact in users behalf. We can do this in back-end by implementing REGEX to get the NAME parameter of the value="Allow", then passed it on to authentication URL - https://foursquare.com/oauth2/authenticate.

$form_data =~ /form method="post" action="(.*?)"(.*?)input value="Allow" type="submit" name="(.*?)" class="input_button"/ig;

$form_action = $1;
$form_allow = $3;

$response = $lwpua->get("https://foursquare.com/oauth2/authenticate?$form_allow=Allow", @header);
$form_data = $response->content;

9. After allowing the application, foursquare will redirect the user to redirect URI that we set on step #7. Your callback URL or redirect URI must capture the CODE parameter and exchange it with TOKEN. This can now be done via PHP.

10. Foursquare will pass the CODE parameter via GET method on our Callback URL. Our Callback URL should be able to capture it and use it in exchange of an access token. To get an access token, we should pass the CODE parameter, Client ID, Client Secret, Callback URL, and Grant Type to the access token URL - https://foursquare.com/oauth2/access_token. Client ID, Client Secret, and Callback URL are data from the consumer registration, and the Grant Type should be equal to "authorization_code". Please take note that this is now on PHP.

$client_id = '<your client id>';
$client_secret = '<your client secret>';
$redirect_uri = '<your callback url>';
$grant_type = 'authorization_code';

$code = $_GET['code'];      
$oauthurl = "https://foursquare.com/oauth2/access_token?client_id=$client_id&client_secret=$client_secret&grant_type=$grant_type&redirect_uri=$redirect_uri&code=$code";

11. As per implementation below, I use the open stream to get the contents and convert it to JSON which will then return an object with an access token.

$url_handler = fopen("$oauthurl", 'r');
$json = json_decode(stream_get_contents($url_handler));
fclose($url_handler);

$token = $json->access_token;

13. Now that you have the Token, we are now ready to do the Foursquare Check-in. Going back to PERL, what we need to do here is to do a POST request to Foursquare API URL - https://api.foursquare.com/v2/checkins/add. venueId will be the place or location you want to check-in, shout is optional if you want your post to have a custom message, broadcast can be of public or private, and lastly the oauth_token which is the access token we get from step #12. Again, this is now in PERL.

$intVenueID = "<the venue id you want to check-in>";
$strShout = "<your shout message>";
$strToken = "<your access token>";

$response = $lwpua->post("https://api.foursquare.com/v2/checkins/add",
                      ['venueId' => $intVenueID,
                       'shout' => $strShout,
                       'oauth_token' => $strToken,
                       'broadcast' => 'public,faceboook,twitter'], @header);

print $response->content;

That's it!! Hope you were able to follow. In case you don't, you can refer to the scripts below. Good luck and enjoy!!

- Here's the PERL script, it composes of 2 sub functions: check_foursquare_login() and post_foursquare_checkin()


#!/usr/bin/perl

require LWP::UserAgent;

use strict;
use warnings;

use HTTP::Cookies;

my $lwpua = LWP::UserAgent->new;

my $user_agent = "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.6) Gecko/20060728 Firefox/1.5.0.6";
my @header = ('Referer' => 'https://foursquare.com',
             'User-Agent' => $user_agent);

my $cookie_file = "cookies.dat";
my $cookie_jar = HTTP::Cookies->new(
                file => $cookie_file,
                autosave => 1,
                ignore_discard => 1);

$lwpua->cookie_jar($cookie_jar);

my $strUser = "<your foursquare username>";
my $strPass = "<your foursquare password>";
my $client_id = "15NGPG2GHI3S1UFMST01FOO0ABPXNFFTGJVTVSZS55W1UN4A";
my $redirect_uri = "http://localhost/foursquare/foursquare.php";
my $status = "testing foursquare status";

my $form_data = &check_foursquare_login($strUser, $strPass, $client_id, $redirect_uri);

if ($form_data =~ /^OK\|/)
{
  my ($strTag, $intUserID, $strToken) = split /\|/, $form_data, 3;
  &post_foursquare_checkin($intUserID, $strToken, '', $status);

  unlink($cookie_file);
  print "done!";
}
else
{
  $form_data =~ /form method="post" action="(.*?)"(.*?)input value="Allow" type="submit" name="(.*?)" class="input_button"/ig;

  my $form_action = $1;
  my $form_allow = $3;

  my $response = $lwpua->get("https://foursquare.com/oauth2/authenticate?$form_allow=Allow", @header);
  $form_data = $response->content;

  if ($form_data =~ /^OK\|/)
  {
    my ($strTag, $intUserID, $strToken) = split /\|/, $form_data, 3;
    &post_foursquare_checkin($intUserID, $strToken, '', $status);

    unlink($cookie_file);
    print "done!";
  }
  else
  {
    unlink($cookie_file);
    print "error authentication!";
  }
}

sub check_foursquare_login
{
  my ($strUser, $strPass, $client_id, $redirect_uri) = @_;

  # log-in to foursquare
  my $response = $lwpua->post('https://foursquare.com/mobile/login',
                      ['username' => $strUser,
                       'password' => $strPass], @header);
  $cookie_jar->extract_cookies( $response );
  $cookie_jar->save;

  $response = $lwpua->get("https://foursquare.com/oauth2/authenticate?client_id=$client_id&response_type=code&display=wap&redirect_uri=$redirect_uri", @header);

  $form_data = $response->content;
  $form_data =~ s/\n//g;

  return $form_data;
}

sub post_foursquare_checkin
{
  my ($strUserID, $strToken, $intVenueID, $strShout) = @_;
  my ($response);

  $response = $lwpua->post("https://api.foursquare.com/v2/checkins/add",
                      ['venueId' => $intVenueID,
                       'shout' => $strShout,
                       'oauth_token' => $strToken,
                       'broadcast' => 'public,faceboook,twitter'], @header);

  return $response->content;
}



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- Here's the PHP script. Save this in your web server and set this as your callback URL in consumer registration.


<?

$client_id = "15NGPG2GHI3S1UFMST01FOO0ABPXNFFTGJVTVSZS55W1UN4A"; // hotshots client id
$client_secret = "NEHCL3UL0KS1QJD22NLIQ5RMR4BL4IUZIJZW25VHSJ4JPZKB";
$grant_type = "authorization_code";
$redirect_uri = "http://localhost/foursquare/foursquare.php";

$code = $_GET['code'];

if ($code) {
        // get access token
        $oauthurl = "https://foursquare.com/oauth2/access_token?client_id=$client_id&client_secret=$client_secret&grant_type=$grant_type&redirect_uri=$redirect_uri&code=$code";

        $url_handler = fopen("$oauthurl", 'r');
        $json = json_decode(stream_get_contents($url_handler));
        fclose($url_handler);

        $token = $json->access_token;
        if ($token) {
                $info_contents = `curl https://api.foursquare.com/v2/users/self?oauth_token=$token`;
                $json = json_decode($info_contents);
                $userid = $json->response->user->id;

                echo "OK|$userid|$token";
        }
}


?>


How to embed a custom youtube player in your website

For you to be able to embed a youtube player in your website, you should have a youtube account to access into.

If you have one already, just follow the simple steps below and you were able to create a custom player that you can put into your website.

1. Go to youtube website - http://youtube.com and enter your username and password.

2. Once logged-in, go to custom player page - http://www.youtube.com/custom_player.

3. On the custom player page, enter your desired player name and description.

4. Select the theme color that you like.

5. Select the layout for your player.

6. Choose the content that you want to be played. Contents are either your own videos, your favorite videos, or one of your playlist. Don't forget to click the "Select" button to confirm the contents that you want.

7. To finally generate the code, just click the "Generate Code" button and the embed code will be generated.

8. Copy the embed code and click the "Finish" button to go to your list of players.

9. To add the newly created player into your site, just paste the code you just copied and save it. You should be able to see the player you just created in your site.

10. To edit your players, go to this link - http://www.youtube.com/my_players then select the player you want to edit. The chosen layout will not be editable.

Hope you like it!! This is just a sample implementation. Thank you for reading this post.

Converting numeric values to currency formatted numbers in PERL

While developing a particular report in Perl, I just noticed that my output for currency values are just numbers without commas and decimal points. So, I do some research to check for an existing function in Perl that simply do this conversion but didn't find anything.. No choice.. I have to create a sub function that converts numeric values to currency values, and I did and now sharing this to you..

Please see sample code and sub function that I just created. Hope you like it!!

#!/usr/bin/perl

$number = 4356789; # sample data
$currency = &convert_to_currency($number);

print "Here we go in Peso value: P$currency\n";

sub convert_to_currency
{
        my ($number) = @_;

        $number = sprintf("%.2f", $number);
        $number = "$1,$2$3" while ($number =~ /(.*\d)(\d\d\d)(.*)/i);
        return $number;
}



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CSS class for transparency that all browsers support

Personally, one of my favorite in web designs are transparency. It gives life to your site as you will have layers of texts and images in one look.

It's great thing haa!! but did you know that having that in your site is a challenge for us programmers? That is because we have to consider all browsers to support transparency in one time setting.

Good thing..!! The class below will resolve the implementation of transparency for all browsers.

.transparency {
    opacity: 0.5;
    filter: alpha(opacity=50);
    -moz-opacity: 0.5;
    -khtml-opacity: 0.5;
}

Below are the CSS properties we used:

• opacity: 0.5; - This is the current standard in CSS transparency settings. This will work in most versions of Firefox, Safari, and Opera.
• filter: alpha(opacity=50); - This one is for our best friend IE.
• -moz-opacity: 0.5; - This one you need for way too old version of Mozilla.
• -khtml-opacity: 0.5; - This one you need for old Safari (1.x).

Resource: css-tricks.com

How to create a directory watcher in PERL

Most of the time, we want to achieve a REAL-TIME processing. However, there are some limitations that we don't have control over, and one of the best example is without having a direct connection to the application you are processing into.

One way to achieve a REAL-TIME processing without a direct connection is to have a back-end processing that will watch and process transactions. This is what we called directory watcher.

With this post, it will help you create a directory watcher in PERL. Just follow the simple steps below to do that.

1. Set the look up directory where you want your script to look into.

2. Create a NON-ENDING loop using WHILE() syntax. To create a NON-ENDING loop, we just have to pass a variable or condition that will always results to TRUE. Example below pass a variable 1 that results to TRUE. And as best practice, a SLEEP function should be implemented every end of each loop, this is for the script not to eat too much of the memory.

while(1) {
  # this creates a non ending loop coz 1 is equal to true..

  sleep 1;
}

3. Inside your WHILE loop, you have to OPEN the look up directory by using OPENDIR() syntax. And as best practice, you need to close the directory every end of the loop.

opendir(DIR, $lookup_dir) || die "Cannot opendir $lookup_dir: $!";

4. Loop the files we read from a look up directory.

opendir(DIR, $lookup_dir) || die "Cannot opendir $lookup_dir: $!";
while ($file = readdir(DIR))
{
  # file names from a reading directory...
}
closedir DIR;


Hope you like it!! Please see the complete code below for your implementation.

#!/usr/bin/perl

$lookup_dir = "<directory to look into>";

while(1)
{
        print "lookup directory: $lookup_dir\n";

        opendir(DIR, $lookup_dir) || die "Cannot opendir $lookup_dir: $!";
        while ($file = readdir(DIR))
        {
                if (($file ne '.') && ($file ne '..') && ($file !~ /^\./))
                {
                        print "here file: $file\n";
                        # do what you want with the file...
                }
        }

        closedir DIR;
        sleep 1;
}




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