Quick start
- PHP 5.1 +
Download
With Git
git clone http://github.com/speedmax/h2o-php.gif
With SVN
svn checkout http://h2o-template.googlecode.com/svn/trunk/ h2o
-
Download and extract h2o in your project path or your php include path
Sample file structure setup
myawesome_app/ index.php templates/ index.html h2o/ use
require 'h2o/h2o.php'in your php statement to include h2o library- Below is a quick start code example to get a kick start
- checkout example and specs if you are in the mood for exploration.
templates/index.html
<body>
<head><title>Hello world</title></head>
<body>
Greetings {{ name }}
</body>
</body>
index.php
<?php
require 'h2o/h2o.php';
$h2o = new h2o('index.html');
echo $h2o->render(array('name'=>'Peter Jackson'));
?>
{{ variable }}
Use dot (.) to access attribute of a variable
- key of associative array
- array-index
- object attribute
- object method call
Example
in your template
{{ person.name }}
in php
<?php
$h2o = new H2o('template.tpl');
$person =array(
'name' => 'Peter Jackson', 'age' => 25
);
$h2o->render(compact('person'));
?>
Let’s say you have assigned a person variable in your php script, following
variable tag will print out Peter Jackson
Filters are variable modifiers to manipulate or format the value of a variable.
A filter usually look like this {{ person.name|capitalize }}, a pipe ( | )
character after a variable will apply a filter.
Filter chaining
Let me burrow the image from liquid template
You can chain multiple filters together and use a pipe ( | ) character to separate
them. {{ document.body|escape|nl2br }}
Filter arguments
Filters can accept arguments for example {{ document.description|truncate 20 }}
will display first 20 character of
document description. Moreover, there are cases you want to pass multiple arguments
and you can use comma( , ) to separate them
{{ person.bio|truncate 20, "..." }}
Filter named arguments
h2o uses colon ( : ) to for named arguments to build optional arguments array.
{{ '/images/logo.png' | image_tag width:450, height:250, alt:"company logo" }}
and this translate to php will be this and that is pretty much what happen internally
<?php
echo image_tag("/image/logo.png", array(
'width' => 450,
'height' => 250,
'alt'=>'company logo'
));
?>
Note: Difference with Django, Smarty
H2o do not use colon ( : ) character to separate arguments for readability reasons,
h2o uses comma ( , ) which is more logical.
{% tag %}
Tags are usually very powerful, they controls the logical flow or structure,
iteration. there are inline tags {% inline_tag %} or tags that requires a
close tag. for example: {% if condition %} ... {% endif %}
if tag evaluate a variable or a simple expression. when results true the if tag
body will be render or else part will be rendered.
{% if person.is_adult %}
You are old enough.
{% else %}
sorry, you are too young for that.
{% endif %}
For tag will iterate over a array of items.
{% for task in tasks %}
{{ task }}
{% endfor %}
Above will print all the tasks.
H2o supports template inheritance, it is very powerful and the concept is easy
to understand.
Template inheritance is implemented using block, extends tag, for programmers
who is familiar with object oriented principles this is easy.
Quote from Django doc
… a base skeleton template that contains all the common elements of your
site and defines blocks that child templates can override.
Example:
base.html – to define the base structure of the page.
<html>
<head><title>{%block title %}This is a page title {% endblock %}</title></head>
<body>
<div id="content">
{% block content%}
<h1> Page title </h1>
<p> H2O template inheritance is a powerful tool </p>
{% endblock %}
</div>
<div id="sidebar">
{% block sidebar %}{% endblock %}
</div>
</body>
</html>
As you can see, the base template is a typical web page using a two column layout,
we defined two blocks (content, sidebar) and HTML code common across all your page.
page.html – to define a template specific of a page.
{% extends 'base.html' %}
{% block content %}
<h1> extended page </h1>
<p> Body of extended page</p>
{% endblock %}
{% block sidebar %}
Sidebar contains use links.
{% endblock %}
The page.html extends base.html, now you will be able to override any block
previously defined.
There is a very good article about template inheritance in Django, in area of
template inheritance h2o work exactly the same way.
Power of inheritance is a very good blog post explaining inheritance
Tips
- if you found you have a lot of common element inside the template, it may be a
good idea to put that portion of template in side a block in a base template. - block gives you a hook, especially useful they are useful for javascript, css
too - When defining a block use a short and distinctive name
There are a range of option to set up the template system the way you want it.
<?php
$h2o = new H2o('template.tpl', array(
[option_name] => [option_value]
));
?>
name of loader or a instance of H2o_Loader
Use file loader [default]
$template = new H2o('index.html', array('loader'=>'file');
Advance setup
<?php
$loader = new H2o_File_Loader($custom_searchpath);
$template = new H2o(‘index.html’, array(‘loader’=> $loader );
?>
Use dictionary loader
You may want to load template from other resource than file then this will be your
friend. h2o use dict_loader() for testing.
<?php
$loader = dict_loader(array(
"index.html" => 'Hello {{ person }}'
));
$template = new H2o('index.html', array('loader' => $loader'));
?>
default: this will be the base path of your template
h2o use this path to load additional templates and extensions.
You can either explicity set the search path
$template = new H2o('index.html', array('searchpath' => '/sites/common_templates'));
or It will try to find the searchpath for you
$template = new H2o('/sites/common_templates/index.html');
define type of caching engine h2o needs to use, set to false to disable
caching, you can read more about performance and caching in following sections
use file cache [default]
$template = new H2o('index.html', array('cache'=>'file'));
use apc cache
$template = new H2o('index.html', array('cache'=>'apc'));
memcache module not implemented yet
disable caching
$template = new H2o('index.html', array('cache'=>false));
When file cache is used, you can define where you want templates to be cached.
it will put cached template in same location as that template
$template = new H2o('index.html', array('cache_dir'=>'/tmp/cached_templates'));
how long template cache will be lived (defaults: 1 hour), template fregment cache that is bundled
in cache extension will use this as default ttl value.
$template = new H2o('index.html', array('cache_ttl' => 3600));