Hi all please advice me on the ‘proper’ way to handle the questions
below. Any insight, best-practise or hint is very welcome. I use Ruby
for a while, but Rails is new to me.
==Initial code:
===My DB contains:
CREATE TABLE posts (
id int(10) unsigned NOT NULL auto_increment,
name varchar(50) NOT NULL,
parent int(10) unsigned default NULL,
description varchar(255) NOT NULL,
PRIMARY KEY (id),
UNIQUE KEY name (name)
);
INSERT INTO posts VALUES (1, ‘mainroot’, NULL, ‘a root-post without
a parent, but with childs’);
INSERT INTO posts VALUES (2, ‘left trunk’, 1, ‘this root has a
parent and child’);
INSERT INTO posts VALUES (3, ‘left leaf’, 2, ‘a leaf-post with
parent, but without child’);
INSERT INTO posts VALUES (4, ‘right leaf’, 1, ‘this leaf-post has a
parent, but no child’);
===My model file post.rb contains:
class Post < ActiveRecord::Base
def Post::find_roots
all_posts = Post::find_all
all_posts.find_all {|post| not post.has_parent?}
end
def has_parent?
not @parent == nil
end
end
The DB has only an id of the parent post, so I try to map this to a
post-object like this:
class Post < ActiveRecord::Base
attr_reader :parent
def initialize(*args)
puts “TEST”
super(*args)
unless self.parent_id == nil
@parent = Post::get_id(self.parent_id)
else
@parent = nil
end
end
end
??When I run http://localhost:3001/Post/list I get a list of posts, so
so far so good but “TEST” is not printed, so it seems like
Post#initialize is never called. Is this true? And how to solve this?
===Controller-file:
class PostController < ApplicationController
scaffold :post
def list
@posts = Post::find_roots
puts @posts.length
end
end
By the way, the controller-file (above) doesn’t print the number of
root-posts, but prints the total number of posts. This is makes sence,
since Post#initialize above was never run…
Reading a bit more on internet about relations I find that the Rails’
way of handling relations is more like:
==New code:
===DB:
ALTER TABLE posts CHANGE parent post_id INT( 10 ) UNSIGNED NULL
DEFAULT NULL
This is a bit more cryptic, but Rails expects this name in the next
step.
??Is there any way to use a different fieldname here? ‘Parent’ is a
lot more explaining then ‘post_id’…
===New model-file:
class Post < ActiveRecord::Base
belongs_to :post
has_many :post
def Post::find_roots
all_posts = Post::find_all
all_posts.find_all {|post| not post.has_parent?}
end
def has_parent?
not self.post == nil
end
end
??For some reason this makes the controller (described above) return
zero. Is my Post#has_parent? correct? A test shows that it is called
for all elements, but the test contained is somehow wrong.
Basically: am I on the right by implementing the relation between Post
and parent-Post like this?
All insight and tips are welcome!
Cheers,
Paul
