2 Models => Town and Island
# Town.rb
belongs_to :player
belongs_to :island
# Island.rb
has_many :towns
The connection occurs via 2 different integer variables
:island_x
:island_y
e.g. :island_x => 34 :island_y => 43
How can i set this association up ?
# CreateIslands
create_table :islands, id: false do |t|
t.primary_key :grepo_id
t.integer :island_x
t.integer :island_y
t.integer :type_number
t.integer :available_towns
t.timestamps
end
# CreateTowns
create_table :towns, id: false do |t|
t.primary_key :grepo_id
t.integer :player_id
t.string :name
t.integer :island_x
t.integer :island_y
t.integer :slot
t.integer :points
t.timestamps
end
Something like this
Class Town < ActiveRecord::Base
belongs_to :player
belongs_to :island ,foreign_key :island_x
end
Update
I see there is no use of island_x and island_y in both the schemas.You can just have a normal foreign_key island_id in the towns table and you can make a call town.island or island.towns.
Update1
I got it wrong with foreignn_key above.You can just make a method and make the matching like this
def some_method
#island_x = Island.find(params[:island_x])
#island_y = Island.find(params[:island_x])
#town_x = Town.where(:island_x => #island_x.id)
#town_y = Town.where(:island_y => #island_y.id)
end
Related
My models
CAR BRANDS MODEL
class CarBrand < ActiveRecord::Base
has_many :car_ads
end
CAR ADVERTISEMENTS MODEL
class CarAd < ActiveRecord::Base
has_one :car_brand
end
my controller:
def index
#car_ads = CarAd.all.order("car_ads.created_at DESC")
end
car ads migrations:
class CreateCarAds < ActiveRecord::Migration
def up
create_table :car_ads do |t|
t.integer "user_id"
t.integer "car_brand_id"
t.integer "car_model_id"
t.integer "state_id", :limit => 2
t.integer "vin_id"
t.integer "year_manufac", :precision => 4
t.integer "km_age"
t.integer "price_usd", :limit => 7
t.integer "car_tel_number", :precision => 8
t.float "motor_volume", :limit => 10
t.string "transmission"
t.integer "horse_power", :limit => 3
t.text "description"
t.boolean "visible", :default => true
t.boolean "active", :default => true
t.string "photo_file_name"
t.string "photo_content_type"
t.integer "photo_file_size"
t.datetime "photo_updated_at"
t.timestamps null: false
end
add_index :car_ads, :user_id
add_index :car_ads, :car_brand_id
add_index :car_ads, :car_model_id
add_index :car_ads, :state_id
add_index :car_ads, :vin_id
end
def down
drop_table :car_ads
end
end
Car brands migratiions
class CreateCarBrands < ActiveRecord::Migration
def up
create_table :car_brands do |t|
t.string "brand", :limit => 20
t.timestamps null: false
end
end
def down
drop_table :car_brands
end
end
so the problem is that i cant get car brand form car ads, please help,
i wanted to get that like
iterating
<% #car_ads.each do |carad|%>
<%= carad.car_brand %>
<%end%>
Modify CAR ADVERTISEMENTS MODEL
class CarAd < ActiveRecord::Base
belongs_to :car_brand
end
Modify your controller:
def index
#car_ads = CarAd.all.order("created_at DESC")
end
You didn't add any reference to CarBrand in CarAd table, just add the car_ad_id column with a migration like this
class AddCarBradIdToCarAd < ActiveRecord::Migration
def change
add_column :car_ads, :car_brand_id, :integer
end
end
So rails would be able to get the corresponding CarBrand from a CarAd
I'm trying to use a :has_many :through type association, but I'm getting the following error:
ActiveRecord::StatementInvalid: SQLite3::SQLException: no such column: work_units.developer_id:
Many other posts about this sort of thing have just had spelling mistakes, but I've checked mine.
class Developer < ActiveRecord::Base
attr_accessible :skype_name, :language_ids, :user_attributes
has_many :work_units
has_many :projects, :through => :work_units
...
end
class Project < ActiveRecord::Base
attr_accessible :complete, :description, :finalised, :price
has_many :work_units
has_many :developers, :through => :work_units
...
end
class WorkUnit < ActiveRecord::Base
attr_accessible :hours_worked
belongs_to :project
belongs_to :developer
end
I've run db:migrate and it didn't complain. I did make a mistake and had to rollback the db then re-migrate, but I think I did it right. I use the annotate gem and it doesn't show any of the relationship ids I'd expect. So, do I need to create a WorkUnits table or am I missing something? The rails guide didn't mention manually making tables.
Edit
Here's the migration I used to create the WorkUnit model and stuff:
class CreateWorkUnits < ActiveRecord::Migration
def change
create_table :work_units do |t|
t.integer :hours_worked, :default => 0
t.timestamps
end
end
end
Edit 2
Snippets from my schema.rb:
create_table "work_units", :force => true do |t|
t.integer "hours_worked", :default => 0
t.datetime "created_at", :null => false
t.datetime "updated_at", :null => false
end
create_table "projects", :force => true do |t|
t.string "description"
t.decimal "price", :precision => 8, :scale => 2
t.boolean "complete", :default => false
t.datetime "created_at", :null => false
t.datetime "updated_at", :null => false
end
Similarly for :developers. So, why doesn't my migration add the association information for me?
Your WorkUnit migration should look like this:
class CreateWorkUnits < ActiveRecord::Migration
def change
create_table :work_units do |t|
t.integer :hours_worked, :default => 0
t.references :developer
t.references :project
t.timestamps
end
add_index :work_units, :developer_id
add_index :work_units, :project_id
end
end
You need to add the foreign keys to your work_units table.
class CreateWorkUnits < ActiveRecord::Migration
def change
create_table :work_units do |t|
t.integer :hours_worked, :default => 0
t.integer :project_id, null: false
t.integer :developer_id, null: false
t.timestamps
end
add_index :work_units, :project_id
add_index :work_units, :developer_id
end
end
Another way:
class CreateWorkUnits < ActiveRecord::Migration
def change
create_table :work_units do |t|
t.integer :hours_worked, :default => 0
t.belongs_to :project
t.belongs_to :developer
t.timestamps
end
add_index :work_units, :project_id
add_index :work_units, :developer_id
end
end
You can also define these fields when generating your model, then they'll be added to the migration automatically as show in the second snippet.
$ rails g model WorkUnit hours_worked:integer project:belongs_to developer:belongs_to
Hope that helps.
A table for WorkUnit needs to exist, whether that means it migration was automatically generated via scaffolding or if the migration was manually written by you.
If you don't have a migration yet that creates that table, you'll need to create that migration because the table does need to exist.
You do need a work_units table with a project_id and developer_id column.
Have a look at http://xyzpub.com/en/ruby-on-rails/3.2/activerecord_datenbank_anlegen.html if you don't know how to create a table.
so i have 2 models:
create_table "holders", :force => true do |t|
t.string "faceid"
t.integer "badges_id"
t.datetime "created_at", :null => false
t.datetime "updated_at", :null => false
end
add_index "holders", ["badges_id"], :name => "index_holders_on_badges_id"
create_table "badges", :force => true do |t|
t.string "name"
t.text "description"
t.datetime "created_at", :null => false
t.datetime "updated_at", :null => false
end
i need 2 things:
to get all the badges of a certain faceid holder
to get all the holders of a certain badge.
i know its really noobs question but until now i didnt work with references so i dont really understood from the literature how to make the connection.
You actually need a many to many association on your holder and badge models. So you have to options either use has many :through or use has_and_belongs_to_many. The difference between the two can be found here. I am taking the example for has_many :through.
You need to create three models.
class Holder < ActiveRecord:Base
has_many :badges_holders
has_many :badges, :through => :badges_holders
end
class Badge < ActiveRecord:Base
has_many :badges_holders
has_many :holders, :through => :badges_holders
end
class BadgesHolder < ActiveRecord:Base
belongs :badge
belongs :holder
end
And your migration files needs to be:
create_table "holders", :force => true do |t|
t.string "faceid"
t.timestamps
end
add_index "holders", ["badges_id"], :name => "index_holders_on_badges_id"
create_table "badges", :force => true do |t|
t.string "name"
t.text "description"
t.timestamps
end
create_table "badges_holders", :force => true do |t|
t.integer "holder_id"
t.integer "badge_id"
t.timestamps
end
Now you can easily use Holder.find_by_faceid('xyz').badges to find the all hedges held by the holder whose faced is xyz. And Badge.first.holders to get all the holders for the first bedge.
For your question HABTM will be a good option as you do not need any extra field in the join table, so you can just use has_and_belongs_to_many in both of your models and you don't need BadgesHolder model in that case. And for the migration of the join table, replace first line with create_table "badges_holders", :id => false, :force => true do |t| a and remove t.timestamps as the join table for HABTM should not have any other column than the foreign keys.
If it's some Ruby on Rails, you must have 2 models :
class Holder < ActiveRecord:Base
has_many :badges
end
class Badge < ActiveRecord:Base
belongs_to :holder
end
Your entry called badges_id should not be in your holders table ; you should have a holder_id on your "badges" table.
Then, you can simply call
Holder.find_by_faceid('foobar').badges
and
Badge.find(1337).holder
If your badge can belongs to many holders, then you have to write a has_and_belongs_to_many relation.
class Product < ActiveRecord::Base
has_many :models, :dependent => :destroy, :order => 'display, title'
class Model < ActiveRecord::Base
belongs_to :product
class GsCollector < ActiveRecord::Base
belongs_to :model
Why can't I do the following in my form for GsCollector?:
<p>
Model:<br />
<%= collection_select :gs_collector, :model_id, Product.where("title = 'Some Title'").models.all, :id, :title %>
</p>
I get the error:
undefined method `models' for #<ActiveRecord::Relation:0x007fef0ac09350>
Shouldn't the models method be provided by the relation? In the console, this works:
p = Product.find(4).models
But this doesn't:
p = Product.where("title = 'some title'").models
Not sure what the difference is....
Here's my schema:
create_table "gs_collectors", :force => true do |t|
t.integer "project_id"
t.integer "model_id"
t.integer "quantity", :default => 1
t.string "housing", :default => "Base Unit"
t.string "hopper"
t.string "controller"
t.boolean "overbags", :default => false
t.datetime "created_at", :null => false
t.datetime "updated_at", :null => false
end
create_table "models", :force => true do |t|
t.string "title"
t.integer "product_id"
t.datetime "created_at"
t.datetime "updated_at"
t.integer "display"
end
create_table "products", :force => true do |t|
t.string "title"
t.datetime "created_at"
t.datetime "updated_at"
end
You are returning an array of objects, collectively called a ActiveRecord::Relation. This is due to your where search term. Maybe you want something like the following:
p = Product.find_by_title('some title').models
where returns a list of Products
find returns a single Product
You need to define the relationship between Model and GsCollector both ways. You forgot the part in the Model:
class Model < ActiveRecord::Base
belongs_to :product
has_many :gs_collectors
end
class GsCollector < ActiveRecord::Base
belongs_to :model
end
And the real problem is that you can .models only on a single record. Product.where returns several ones - so use Product.find_by_title("title").models
I'm a complete rails newbie, so forgive me if this is trivial.
I have an Inventory model that either belongs_to a Store or a Traveling Party:
class Inventory < ActiveRecord::Base
belongs_to :trader, :polymorphic => true
end
class Store < ActiveRecord::Base
has_one :inventory, :as => :trader, :dependent => :destroy
end
class TravelingParty < ActiveRecord::Base
has_many :travelers, :dependent => :destroy
has_one :inventory, :as => :trader, :dependent => :destroy
validates_presence_of :speed, :ration, :position
accepts_nested_attributes_for :travelers, :reject_if => :reject_traveler, :allow_destroy => true
accepts_nested_attributes_for :inventory, :allow_destroy => true
def reject_traveler(attributes)
attributes['profession'].blank? and attributes['name'].blank?
end
end
I created a form that, when submitted, creates a Traveling Party and a number of Travelers. Now I'd like the form to also create an Inventory and initialize all the variables to 0. I know the following doesn't address variable initialization, but it doesn't even seem to put a row of null values into the Inventory database table.
class TravelingPartiesController < ApplicationController
def new
#traveling_party = TravelingParty.new
5.times do
traveler = #traveling_party.travelers.build
end
#inventory = #traveling_party.inventory.create
end
def create
#traveling_party = TravelingParty.new(params[:traveling_party])
if #traveling_party.save
flash[:notice] = "Successfully created traveling party and travelers."
redirect_to '/store/'
else
flash[:error] = "Please specify a leader."
redirect_to '/new/'
end
end
def index
end
end
For good measure, here is what the database schema looks like:
ActiveRecord::Schema.define(:version => 20111018224808) do
create_table "inventories", :force => true do |t|
t.integer "ox"
t.integer "food"
t.integer "clothing"
t.integer "ammunition"
t.integer "money"
t.integer "axle"
t.integer "wheel"
t.integer "tongue"
t.datetime "created_at"
t.datetime "updated_at"
t.integer "trader_id"
end
create_table "stores", :force => true do |t|
t.string "name"
t.integer "location"
t.integer "priceScale"
t.datetime "created_at"
t.datetime "updated_at"
end
# Could not dump table "travelers" because of following StandardError
# Unknown type 'relations' for column 'traveling_party_id'
create_table "traveling_parties", :force => true do |t|
t.integer "speed"
t.integer "ration"
t.integer "position"
t.datetime "created_at"
t.datetime "updated_at"
end
end
Is there a reason the inventory database table isn't being affected at all? And once that works, what would be the best way to initialize a traveling_party.inventory to have all 0s? (i.e., values for ox, food, clothing, etc).
This may because your inventories table does not include a 'trader_type'. This is required for polymorphic associations.
create_table "inventories", :force => true do |t|
t.integer "trader_id"
t.string "trader_type"
end
Edit:
To set all the values initially to 0, the best way would be to put a default value onto the fields in the table. (If you want it to always be initialized to 0 if there is no other option, otherwise they will default to nil)
I believe you can create a migration with
change_table(:inventories) do |t|
t.change :ox, :integer, :default => 0
end