ruby on rails - Update parent object when child objects meet certain condition -

i have 2 models - order , item:

order.rb:

class order < activerecord::base   has_many :items end 

item.rb:

class item < activerecord::base belongs_to :order end 

schema item:

t.decimal  "price",       precision: 12, scale: 3 t.string   "status" 

schema order:

 t.string   "status" 

item's status marked shipped when user received items. how can update order status "complete", in condition items' status updated "shipped"?

you need update items table include foreign key, relating orders:

$ rails g new migration addorderidtoitems  #db/migrate/add_order_id_to_items______.rb class addorderidtoitems < activerecord::migration    def change       add_column :items, :order_id, :integer    end end  $ rake db:migrate 

you can read more why important here:

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this allow following:

#app/models/order.rb class order < activerecord::base    has_many :items, inverse_of: :order end  #app/models/item.rb class item < activerecord::base    belongs_to :order, inverse_of: :items    after_save :check_order, on: :update     private     def check_order       items = item.where(order_id: order.id).where.not(status: "shipped").count       order.update(status: "complete") if items > 0    end end 

this allow use following:

@item = item.find params[:id] @item.update(status: "shipped") #-> "check_order" happen, saving "order" "complete" if items shipped 

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the real fix create has_many :through relationship, associate many items many orders. way, can mark each of orderitems "shipped":

#app/models/order.rb class order < activerecord::base    has_many :order_items    has_many :items, through: :order_items end  #app/models/order_item.rb class orderitem < activerecord::base    #columns id | order_id | item_id | created_at | updated_at    belongs_to :order    belongs_to :item     after_save :check_order, on: :update     private     def check_order       items = item.where(order_id: order.id).where.not(status: "shipped").count       order.update(status: "complete") if items > 0    end end  #app/models/item.rb class item < activerecord::base    has_many :order_items    has_many :orders, through: :order_items end 

you need introduce orderitem model (changes item , order models not necessary):

this allow following:

@order = order.find params[:id] @item = item.find params[:id]  @order.items << @item #-> adds "item" order  

you'll able use following set whether order has been "completed" or not:

@order = order.find params[:id]  @item = @order.order_items.find x @item.update status: "shipped"