ruby on rails - Lost the last object assigned using rails_admin -

i'm using rails_admin have crud functionality on models. have 2 models category , project. project can have 1 category 1 category can in many projects. problem when created 2 different projects same category previous 1 lost relation, last 1 created keep it. how can create different projects same category.

my models are:

category

class category < activerecord::base   belongs_to :project, :inverse_of => :category  end 

project

class project < activerecord::base   has_one :category, :dependent => :destroy, :inverse_of => :project    def category_id     self.category.try :id   end   def category_id=(id)     self.category = category.find_by_id(id)   end  end 

the relationships seeking of are:

• project belongs_to category
• category has_many projects

the belongs_to relationship declared category in model file says each category object can bind 1 project object.

have @ http://guides.rubyonrails.org/association_basics.html#choosing-between-belongs-to-and-has-one find out more 2 relationships using.