CakePHP - MVC Model Associations - How can I structure this data model?

Question

quick question that I have been stuck with since hours:

For my cakePHP website project (using version 2.0) I have 2 Models. They are a bit obscure so I'll translate the model to the standard blog post models.

So I have a "Posts" model and for those many "Categories".

class Post
$belongsTo = 'Category'

class Category
$hasMany = 'Post'

So far so good. Now I want every category to have exactly one (mandatory) 'main post'.

How would I associate that?

• Another 'MainPost' Model? That seems redundant as it would have the same content as the posts.
• A boolean 'is_main' column in the posts? Doesn't seem right since only one post of each category is allowed to be "main".
• A 'mainpost_id' column in the categories? Sounds good but "$belongsTo" is the only association that allows the foreign key to be in the current class. And to say that a Category belongsTo Post when the opposite is also true seems wrong to me. Also belongsTo is a many-to-one association and what I want is kind of a one-to-one association.

Please help me, [insert name]. You're my only hope. ;)

Edit: I guess it would be great if there was a way to have a "hasOne" relationship but have the foreign key in the same class that $hasOne X and not in the other as is standard.

Answer 1

Here is one solution:

[ categories ]
id
name
mainpost_id

[ posts ]
id
category_id
title
text

• Category hasMany Post
• Post belongsTo Category
• Category hasOne MainPost (see code)