Add a Group-By Scope to Yii's CActiveRecord Subclass

on Friday, April 13, 2012
Keywords: , , , 0 comments
Yii Framework allows for named scopes to be added to a CActiveRecord's subclass (you can read more about this here). This also makes it more convenient to filter models based on a predetermined criteria. You can chain them with any filter methods of that class, and ultimately the CDbCriteria methods like `findAll()`.

To site an example, let's have a database table named `animals`. It also has the following fields: id, name, and classification. Let's fill this up with some data. I know this can still be normalized, but let's just leave it like this for the sake of simplicity.

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[ 1, 'Eagle',     'Bird']
[ 2, 'Peacock',   'Bird']
[ 3, 'Kangaroo',  'Mammal']
[ 4, 'Dog',       'Mammal']
[ 5, 'Horse',     'Mammal']
[ 6, 'Snake',     'Reptile']
[ 7, 'Turtle',    'Reptile']
[ 8, 'Lizard',    'Reptile']
[ 9, 'Crocodile', 'Reptile']
[10, 'Spider',    'Arthropods']

Now, assuming we're asked to provide a summary of classifications, like return a list of classifications with a number of animals in each of them. This is how our sql query looks like if nothing else is added in the criteria.

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SELECT t.classification, COUNT(*) AS animalCount
  FROM `animals` AS t
  GROUP BY t.classification
  ORDER BY animalCount DESC;

If you try to run this query, the result looks something like this.

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[Reptile,     4]
[Mammal,      3]
[Bird,        2]
[Arthropods,  1]

Let's assume that we've created a model class named `Animal`, which represents our `animals` db table and has the following method which does the same thing as the aforementioned sql query. It looks like the following:

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public function scopes()
{
  return array(
    'groupByClass' => array(
      'group'   => 't.classification',
      'select'  => 't.classification, COUNT(*) as animalCount',
      'order'   => 'animalCount DESC',
    ),
  );
}

This is the overriden method coming from CActiveRecord. To use this, we simply type:

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Animal::method()->groupByClass()->findAll();

Then we get the same result:

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[Reptile,     4]
[Mammal,      3]
[Bird,        2]
[Arthropods,  1]

You must be wondering how the heck I'm supposed to access `animalCount` alias. Well for that, we can simply add a special property. That would of course be of the same name, which is `animalCount`.

So there you have it.

Facebook IFrame App in Safari

Keywords: , , , 3 comments
You don't really need cookies to make your Facebook IFrame app work in Safari browser. I remember two years ago, to make Page Tab applications work in Safari, you only need to make use of this trick. I won't be explaining it in details here.

Just recently, I was asked to do this new Fb project that's intended for Page Tab, which now is an iFrame-only platform. I've been developing it using Chrome browser. And when I finally get to test it on Safari, unsurprisingly, it's the same old scenario. What's worse is that the old trick won't work anymore (you better read this).

This app relies so much on Javascript. And instead of deploying several php pages, I only need to come up with a startup page which when loaded on the iFrame, loads the rest of the required scripts. Other pages are dynamically constructed using html fragments that are parsed by a templating script. So most of the Client-Server transactions are done asynchronously. And with Safari continously blocking third-party cookies, it just doesn't work.

After hours of googling for answers, I turned to Facebook's PHP SDK. I found out that it doesn't really require you to use cookies after all (now at 3.1.1). If you take a look at `BaseFacebook` class, particularly the `getSignedRequest` method, you'll see that it first checks the request parameter for Signed Request data (they used to have `session` before this).

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...
public function getSignedRequest() {
  if (!$this->signedRequest) {
    if (isset($_REQUEST['signed_request'])) {
      $this->signedRequest = $this->parseSignedRequest(
        $_REQUEST['signed_request']);
    } else if (isset($_COOKIE[$this->getSignedRequestCookieName()])) {
      $this->signedRequest = $this->parseSignedRequest(
        $_COOKIE[$this->getSignedRequestCookieName()]);
    }
  }
  return $this->signedRequest;
}
...

With this in mind, it's possible to send `signed_request` data along with an Ajax request which the PHP SDK can use to determine the user and for your app to verify as well. I use FB.getLoginStatus to acquire a copy of this data. This of course assumes that the user has already authorized your app. Otherwise you'll have to let him do so.

The following example uses jQuery's `$.ajax`.

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...
$.ajax({
  url: BACKEND_LINK_HERE,
  type: 'POST',
  data: {
    signed_request: 'sOm3ReA||yLo0ooooooo...oooooooooNgT3xtHeR3',
    another_data: 12345
  }
})
...

So that's it. You need to make sure you have a valid `signed_request` data each time a user interacts with your application. Don't even think about storing it because the access token contained will soon expire which then deems it useless (about 2.5 hours from the moment the user interacted with your app). Yes that's right. And just to let you know, `offline_access` is no longer supported.

Here's a Facebook article about handling invalid and expired access tokens in case you're interested.


Related posts:

Facebook FB.getLoginStatus() Not Working

on Tuesday, April 03, 2012
Keywords: , , 2 comments
A lot of them complaining about `FB.getLoginStatus` method not responding. Lucky you, I'm one of them. This is just one of those things common to us when developing an application on Facebook platform. Perhaps the reason why sometimes, changes just seem so hard to adapt. At least only at first.

FB.getLoginStatus(function(response) {
  if (response.status === 'connected') {
    // the user is logged in and has authenticated your
    // app, and response.authResponse supplies
    // the user's ID, a valid access token, a signed
    // request, and the time the access token 
    // and signed request each expire

    var uid = response.authResponse.userID;
    var accessToken = response.authResponse.accessToken;

  } else if (response.status === 'not_authorized') {
    // the user is logged in to Facebook, 
    // but has not authenticated your app

  } else {
    // the user isn't logged in to Facebook.
  }
 });

My application is intended for Page Tab. I'm one of the administrators of it and it's being run on Sandbox Mode.

So here's what I did to solve this issue.



  • go to app's settings page, then Basic tab.
  • fill up `Site URL` field for `Website` under `Select how your app integrates with Facebook` section.
  • hit Save button then reload your app (canvas, page tab,...)

You should see FB.getLoginStatus() in action by now.


Related posts: