How to build a recursive parenting structure?


#1

I’m just getting used to using HABTM structures. Something I’m trying
to do now is create a site that has “sections” each section then could
have a sub “section”.

So I built a “sections” table and in the model I included the line
“has_and_belongs_to_many :sections”
I also made a table called “sections_sections” to build the heirarchy
however the fields I generated were:

CREATE TABLE sections_sections (
section_id INT( 10 ) UNSIGNED NOT NULL,
parent_id INT( 10 ) UNSIGNED NOT NULL ,
constraint fk_parents foreign key (parent_id) references sections(id),
constraint fk_sections foreign key (section_id) references sections(id)
);

Because I can’t have two section_id fields. So how can I let rails know
that it should look for parent_id when I do something like:
@section.sections.include?(@section_to_look_for)?


#2

Sounds like what you’re looking for is :acts_as_tree
Unless a section can have more than one parent, there is
no need for a HABTM table, just put the parent_id column
in the sections table, and add :acts_as_tree.

joshua