Jinja/Django-like Template Inheritance for CodeIgniter

Description

This CodeIgniter-helper provides a stripped-down flavour of Jinja/Django - specifically, only inheritance, which we know as {% extends %} and {% block %} in Jinja/Django.

Unlike Jinja/Django, the template is not run through a lexer. Block markers and the extends directive are all specified in PHP code, instead of '{%'/'%}' tags, reducing possible performance hits.

Usage

1. Download/Checkout a copy of the repo into the libraries/ folder of either your application directory or core CodeIgniter directory.

2. In your index.php or applications config, add the following constants:

   // Name of folder that this repo is in.
   define('JINJA_INHERITANCE_DIRNAME', 'codeigniter-jinja-inheritance');
   // Full path to the repo.
   define('JINJA_INHERITANCE_PATH', APPPATH.'libraries/'.JINJA_INHERITANCE_DIRNAME);
   

   Change APPPATH to BASEPATH in the second define() if you've placed the repo in the core CodeIgniter folder.

3. In your controller, load the library, and load your view as you normally would - but this time with our new library, instead of the built-in View library:

   function a_func() {
     $this->load->library(JINJA_INHERITANCE_DIRNAME.'/JI_Loader', NULL, 'ji_load');
     $this->ji_load->view('a_view');
   }
   

   For more on the arguments accepted by library(), please see the Loader documentation <https://codeigniter.com/user_guide/libraries/loader.html>.

   See also Skeleton Controller.

Tags/Functions

The three template-inheritance tags in Jinja/Django are provided.

These methods are available in views via $this, as we've overriden CodeIgniter's default Loader implementation.

• extends_view('*view_name*')

  Jinja/Django: {% extends %}

  Specify view_name as you would a CodeIgniter view.

• start_block('*block_name*')

  Jinja/Django: {% block %}

• end_block(['*block_name*'])

  Jinja/Django: {% endblock %}

Skeleton Controller

It may be quite a hassle to define a new function for every (trivial) page - here's a simple controller that takes care of all this:

class Site extends Controller {
      /*
       * Define non-trivial functions here.
       */
      static special_funcs = array(
              'do_smtg_special'
      );
      /*
       * For your non-trivial functions, just call this function to render
       * your Jinja-style views.
       */
      function _ji_view($view) {
              $this->load->library(JINJA_INHERITANCE_DIRNAME.'/JI_Loader', NULL, 'ji_load');
              $this->ji_load->view($view);
      }
      /*
       * Define `_remap`, a special function in CI; see
       *
       *   https://codeigniter.com/user_guide/general/controllers.html#remapping
       *
       * for more details.
       *
       * Note: AFAIK, segments aren't passed in.
       */
      function _remap($page) {
              if (array_key_exists($page, self::$special_funcs))
                      call_user_func(array(&$this, $page));
              else
                      $this->_ji_view("page-{$page}");
      }
}

Examples

Simple Inheritance

base.php:

A heading.
<?php $this->start_block("content"); ?>
Content goes here.
<?php $this->end_block(); /* block name is optional */?>

index.php:

<?php $this->extends_view("base"); ?>
<?php $this->start_block("content"); ?>
Welcome to foo.com!
<?php $this->end_block("content"); /* block name is optional */?>

result:

A heading.
Welcome to foo.com!

Nested Blocks

base.php:

A heading.
<?php $this->start_block("content"); ?>
<?php $this->start_block("blurb"); ?>
- Welcome to foo.com - where you'll find all things baz.
<?php $this->end_block("blurb");?>
Welcome to foo.com!
<?php $this->end_block(); /* block name is optional */?>

two-column.php:

<?php $this->extends_view("base"); ?>
<?php $this->start_block("content"); ?>
  <?php $this->start_block("blurb"); ?>
  <?php $this->end_block("blurb");?>
  <?php
  // Note: this block wasn't defined in base; it will show up, as expected.
  $this->start_block("text");
  ?>
  <?php $this->end_block("text");?>
<?php $this->end_block(); ?>

index.php:

<?php $this->extends_view("two-column"); ?>
<?php $this->start_block("blurb"); ?>
- Thing are all baz here.
<?php $this->end_block("blurb");?>
<?php $this->start_block("text"); ?>
This is the baz you've been waiting for.
<?php $this->end_block("text");?>

result (extraneous newlines eschewed for presentation purposes):

A heading.
- Thing are all baz here.
This is the baz you've been waiting for.

Licence

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

• Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
• Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
• The name of the author may not be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.