Symfony2：向实体添加方法

I would like to add a method to an Entity. This method returns X characters from the Entity's title, and i would like to print this title in my twig file. Is it possible ?

twig :

<ul class="nav nav-pills nav-stacked">
{% for blog in listBlogs %}
    <li>
        <a href="{{ path('l3_blog_view', {'id': blog.id}) }}">
            {{ blog.getTruncatedTitle }}
        </a>
    </li>
{% endfor %}

entity :

class Blog
{
 /**
 * @var string
 *
 * @ORM\Column(name="content", type="text")
 */
private $content;

public function setTruncatedTitle($content)
{
    $this->content = "Hey";

    return $this;
}

/**
 * Get content
 *
 * @return string 
 */
public function getTruncatedTitle()
{
    return $this->content;
}

}

Looking at your code you replace your content with simple string. But in your template file you do not call that method at all, you directly access your getter. Also what does X characters means? If you want to truncate your title and return part of it, Symfony is providing a really handy filters for that. All you have to do is register the service:

services:
twig.extension.text:
    class: Twig_Extensions_Extension_Text
    tags:
        - { name: twig.extension }

After that its as simple as {{ blog.content | truncate(50) }}. If you want to preserve your words, include its second argument, like this | truncate(50, true). If you want custom separator, include it as 3rd argument.

If I did not understood your question correctly, let me know.

- Update -

If all you want is to define custom method that would do some specific logic to your property, then do it like this:

public function getTruncatedTitle() {
    $title = $this->title; // or $this->content - whatever suits your needs.

    // You can apply your custom logic here like that.
    return substr($title, 0, 10);
}

Then calling blog.truncatedTitle will invoke that method.