5 Essential CakePHP Interview Questions *

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What’s wrong with this multiple Model Validation rule? Will both, one, or neither rule be executed and why? How might this code be fixed?

'email' => array(
    'rule' => array(
        'rule' => 'notEmpty',
        'message' => 'Email address is required.'
    ),
    'rule' => array(
        'rule' => 'email',
        'message' => 'The email address you entered is invalid.'
    )
)
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The key 'rule' needs to be unique when calling multiple validation rules. In the case above, the notEmpty rule will never be called, as the email rule will simply overwrite it (since the multidimensional array has the same key).

Each key should be unique, e.g:

'email' => array(
    'rule-1' => array(
        'rule' => 'notEmpty',
        'message' => 'Email address is required.
    ),
    'rule-2' => array(
        'rule' => 'email',
        'message' => 'The email address you entered is invalid.'
    )
)
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What is the purpose of $this->set(); when used in the Controller actions, e.g:

$this->set('articles', $articles);

Also, compare the above line of code to the following:

$this->set(compact('articles'));

What are the relative advantages of each? Which would you use and why?

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The set() method is used to create a variable in the view file. In the example above, the variable $articles will then be available to use in the view template file for that action.

An advantage of the first example (i.e., $this->set('articles', $articles); is that it allows the variable name on the view to be different from the variable name on the controller. For example, if you wanted them to be different, you could do something like $this->set('articlesData', $articles);. The variable on the view file would then be $articlesData.

The advantage of the second approach (i.e., $this->set(compact('articles'));, on the other hand, is that it is somewhat neater, and it also is arguably a bit less error-prone. It is also shorter and easier to write, especially where we are setting several variables to the view.

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In the following line of code, how could the Containable behavior be used to optimize the find query so that only the region data is returned (i.e., without any model associations):

$this->Region->find('all');
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The Containable behavior allows the developer to specify which associated models (if any) are retrieved from the find query.

So to ensure that no other associated models are returned in the above example, it could simply be re-written as:

$this->Region->find('all', array('contain' => false));

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A current alternative to the Containable behavior is to use the recursive function. Why is the use of the recursive function below incorrect in a case where we want to only retrieve the region data without any model associations?

$this->Region->find('all', array('recursive' => 0));
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The use of recursive is incorrect in the above example (if we don’t want to pull any associated data) since recursive works as follows:

  • -1 – No associated data is retrieved with the find query.
  • 0 – Retrieves any BelongsTo associated data.
  • 1 – Retrieves any directly related associations (i.e., BelongsTo, HasMany, HasOne, HasAndBelongsToMany).
  • 2 – Retrieves any directly related associations, and their associations’ associations.

So in the above, example, -1 should have been used (rather than 0) to avoid pulling any associated data.

It is also important to note that recursive is slated to be phased out in CakePHP 3 and replaced solely with the Containable behavior.

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What is the difference between a Component, a Behavior, and a Helper? Provide an example of where and when each might be used.

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All 3 are similar because they act to extend existing CakePHP functionality, but the differ on what they extend:

For example:

  • A shopping cart Component might offer functionality that can be used and shared across multiple Controllers.
  • A custom upload Behavior could be used to extend a Model, for example to add images uploads. Another common example of a Behavior would be to add extra validation functionality beyond that which CakePHP offers by default.
  • A Helper can be used to assist with View functionality. A good example here would be the CK Editor helper that makes it easy to display a CK Editor.
* There is more to interviewing than tricky technical questions, so these are intended merely as a guide. Not every “A” candidate worth hiring will be able to answer them all, nor does answering them all guarantee an “A” candidate. At the end of the day, hiring remains an art, a science — and a lot of work.
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Francisco Sanchez Clariá
Argentina
Francisco is an engineer currently focused on cross-platform apps (Ionic/Cordova) and specialized in hardware-software technology integration. He also has extensive experience in innovative solutions, distributed data manipulation systems, extension of web applications to ease common business tasks, custom UI design, and application usability with a strong focus on sustainability.