creating multiple onetoMany relations in Sumfony 2.5 - php

Question

I am really new to Symfony so I apologize in advanced if this sounds stupid and I will really appreciate if anyone to correct my understanding.
I am reading about Databases and Doctrine and while reading I thought why not create a dummy blog app to practice.
The dummy blog app i am working on is very simple just three tables and its Entity
post (where the blog posts go) its Entity is Entity/Post.php,
comments (where to post comments go) its Entity is Entity/Comments.php
category (where the post categories go) its Entity is Entity/Category.php.
I am able to get the post/category/comments to save, show, update, delete all that is working fine.
What i am working on now is when the blog is displayed, its category appears as a number (category id), so i am trying to link the post table with category table to display the category name rather than number.
Question 1, Since the post is also linked with the comments table and i need to link the same post table with category table can we do this inside the Entity/Post.php?
class Post
{
/**
* #ORM\OneToMany(targetEntity="Comments", mappedBy="post")
*/
/**
* #ORM\ManyToOne(targetEntity="Category", inversedBy="post")
* #ORM\JoinColumn(name="category", referencedColumnName="id")
*/
protected $comment;
protected $categories;
If not then what is the correct way to handle these relationships?
Question 2, While reading "Fetching Related Objects", it seems that I should be able to get the category name my doing the following
$posts = $this->getDoctrine()->getRepository('BlogBundle:Post')->findBy(array('category' => $id), array('id' => 'DESC'));
$category_name = $posts->getCategory();
but this gives me an error
Error: Call to a member function getCategory() on a non-object in
I can confirm that this getCategory() method does exist in Post entity
I will really appreciate any assistance here.

Answer 1

Question 1
The annotations are fine, but you have to write them right on top of the property they belong to, otherwise they are ignored:
class Post
{
/**
* #ORM\OneToMany(targetEntity="Comment", mappedBy="post")
*/
protected $comments;
/**
* #ORM\ManyToOne(targetEntity="Category", inversedBy="posts")
* #ORM\JoinColumn(name="category", referencedColumnName="id")
*/
protected $category;
public function __constructor()
{
$this->comments = new ArrayCollection();
}
// ...
}
Make shure you have the correct counterpart set in the other entities:
class Category
{
/**
* #ORM\OneToMany(targetEntity="Post", mappedBy="category")
*/
protected $posts;
public function __constructor()
{
$this->posts = new ArrayCollection();
}
// ...
}
class Comment
{
/**
* #ORM\ManyToOne(targetEntity="Post", inversedBy="comments")
* #ORM\JoinColumn(name="post", referencedColumnName="id")
*/
protected $post;
// ...
}
Note that I changed some singular / plural of properties and Comments class name. Should be more intuitive like that.
Question 2
findBy returns an array of found objects, even if only one object was found. Use either findOneBy or foreach through your result.