model是MVC里的M

model的读取流程：数据库表=>model类实例=>controller透传=>前端展示

感觉没有python的peewee模块简洁

创建文件：src/AppBundle/Entity/BlogPost.php

<?php
namespace AppBundle\Entity;
use Doctrine\ORM\Mapping as ORM;
/**
 * BlogPost
 *
 * @ORM\Table()
 * @ORM\Entity
 */
class BlogPost
{
    /**
     * @var integer
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;
    /**
     * @var string
     *
     * @ORM\Column(name="title", type="string", length=255)
     */
    private $title;
    /**
     * @var string
     *
     * @ORM\Column(name="body", type="text")
     */
    private $body;
    /**
     * @var \DateTime
     *
     * @ORM\Column(name="create_time", type="datetime")
     */
    private $createTime;
    /**
     * Get id
     *
     * @return integer
     */
    public function getId()
    {
        return $this->id;
    }
    /**
     * Set title
     *
     * @param string $title
     * @return BlogPost
     */
    public function setTitle($title)
    {
        $this->title = $title;
        return $this;
    }
    /**
     * Get title
     *
     * @return string
     */
    public function getTitle()
    {
        return $this->title;
    }
    /**
     * Set body
     *
     * @param string $body
     * @return BlogPost
     */
    public function setBody($body)
    {
        $this->body = $body;
        return $this;
    }
    /**
     * Get body
     *
     * @return string
     */
    public function getBody()
    {
        return $this->body;
    }
    /**
     * @return \DateTime
     */
    public function getCreateTime()
    {
        return $this->createTime;
    }
    /**
     * @param \DateTime $createTime
     */
    public function setCreateTime($createTime)
    {
        $this->createTime = $createTime;
    }
}

说明：
BlogPost这个model从含义上表达了一篇博客，从实现上表达了数据库表的一行，有id、title、body、createTime几个属性，其中id是数据库的主键（自增1，不需要setId方法），title是博客的标题，body是博客内容，createTime是博客创建时间

数据库配置app/config/parameters.yml文件

parameters:
    database_host: 127.0.0.1
    database_port: 3306
    database_name: mywebsite
    database_user: root
    database_password: shareditor@126.COM
    mailer_transport: smtp
    mailer_host: 127.0.0.1
    mailer_user: null
    mailer_password: null
    secret: 1a0cb131fb193436d0f6ce467f2d8b6c7c5b02da

$ php app/console doctrine:database:create  # 初始化数据库
$ php app/console doctrine:schema:update --force  # 新建数据表

手工往数据库里插入一行数据

mysql> insert into blog_post(title,body,create_time) values('这是标题','这是内容',now());

src/AppBundle/Controller/BlogController.php中的showAction方法

public function showAction(Request $request)
    {
        $blogPostRepository = $this->getDoctrine()->getRepository('AppBundle:BlogPost');
        $blogposts = $blogPostRepository->findAll();
        return $this->render('blog/show.html.twig', array('title' => $blogposts[0]->getTitle(), 'content' => $blogposts[0]->getBody()));
    }

app/Resources/views/blog/show.html.twig

{% extends "base.html.twig" %}

{% block title %}博客内容{% endblock title %}

{% block body %}
<div class="row jumbotron">
    <div class="col-md-1 col-xs-1"></div>
    <div class="col-md-10 col-xs-10"><h1>{{ title }}</h1></div>
    <div class="col-md-1 col-xs-1"></div>
</div>
<div class="row">
    <div class="col-md-1 col-xs-1"></div>
    <div class="col-md-10 col-xs-10"><h4>{{ content }}</h4></div>
    <div class="col-md-1 col-xs-1"></div>
</div>
{% endblock body %}

参考：
MVC模式中的Model使用方法