community, I need your help. It's a quite simple problem, but I can't figure out what's wrong.
I have two models, a Product model and a Condition model. A Product can have only one condition, so I set a one-to-many association between the two. Condition contains fixed records (e.g. good, bad, damaged)
Product.rb
attr_accessible :condition_id
has_one :condition
Condition.rb
belongs_to :product
I have a foreign key condition_id in my products table.
In my products form, I loop through the conditions and set the id:
_form.html.erb(Product)
<%= f.select :condition_id, Condition.all.collect {|x| [x.name, x.id]}, {} %>
I can see that the id is set in the console, when I submit the form. But I can't retrieve the value of the given condition.
In my product show page, I try
<%= #product.condition.name %>
but it gives me a "undefined method `name' for nil:NilClass" error. This is also happening when trying in the console.
What am I missing here?
Thank you all!
Sorry, for answering my own question.
It seems that I mixed-matched the association.
So a Product belongs_to :condition and a Condition has_many :products works fine.
However, for me Product has_one :condition and Condition belongs_to :product sounds much more verbose.
Related
I understand that a belongs_to puts the foreign key on the declaring model, and a has_one puts it on the other model. Does that mean there is no difference in this example?
class Category
belongs_to :blog
end
class Blog
end
class Blog
has_one :category
end
class Category
end
The only thing I can see is that the second example's nomenclature makes a little more sense.
Yes.
belongs_to expects the foreign key to be on its table whereas has_one expects it to be on the other:
# here the Category table will need to have a blog_id field
class Category
belongs_to :blog
end
# the blog table won't need anything
class Blog
has_one :category
end
has_one under the hood is similar to has_many except it adds a LIMIT 1 clause to the sql statement when you query the table.
The difference lies in the database, as you've noted. The model with the belongs_to reference must contain the foreign key for the association. When using has_one, it will expect to find a foreign key on the associated model.
I'm building an application in which the user can create a Company and add Investments made to that company. The investments can come from two sources user's Funds or companies' Coinvestors. Funds are big deal in the application as the user can do a bunch of stuff in them. The Coinvestors are not that important, but I want to have control over few aspects of so I created a Model just for them. For that I created a Polymorphic association for which I gave the [terrible] name of Investables. I'm running Rails 3.2.15 and Ruby 2.0.0. Models are below:
class Company < ActiveRecord::Base
has_many :investments
accepts_nested_attributes_for :investments
end
class Investment < ActiveRecord::Base
belongs_to :fund, :class_name => "Fund", :foreign_key => 'investable_id'
belongs_to :company, inverse_of: :investments
belongs_to :coinvestor, :class_name => "Coinvestor", :foreign_key => 'investable_id'
end
class Fund < ActiveRecord::Base
has_many :investments, :as => :investable, :dependent => :destroy
end
class Coinvestor < ActiveRecord::Base
has_many :investments, :as => :investable, :dependent => :destroy
end
When editing the company I want to be able to add investments and I want to dynamically add form lines for each new investment. I was able to achieve that following the awesome 165-Edit Multiple Revised.
To make it more complex, I also want to add a Dropdown for choosing the Polymorphic Type so it filters the next Dropdown to show only the names of either the Funds or the Coinvestors.
For that I mostly adapted code from Railscast 88-Dynamic Select Menus(Thanks Ryan!!)
/views/company/edit.html.erb
<%= form_for(#company) do |f| %>
...
<%= f.fields_for :investments do |builder| %>
<%= render 'investment_fields', f: builder %>
<% end %>
<%= link_to_add_fields "Add Investment", f, :investments, 'table' %>
/views/company/_investment_fields.html.erb
<%= f.select :investable_type , [ "Fund", "Coinvestor" ], {prompt: "Investor Type"} %>
<%= f.grouped_collection_select( :investable_id, investables_to_collection, :investables, :name, :id, :name, {prompt: "Investor"} ) %>
The "investable_to_collection" is a helper I built to aggregate objects from both Funds and Coinvestors models.
module CompaniesHelper
InvestableCollection = Struct.new(:name, :investables)
CollectionItem = Struct.new(:name, :id)
def investables_to_collection
a = Array.new
a << InvestableCollection.new('Fund', Fund.all.map { |item| CollectionItem.new(item.name, item.id )})
a << InvestableCollection.new('Coinvestor', Coinvestor.all.map { |item| CollectionItem.new(item.name, item.id )})
a
end
end
I didn't add any JavaScript yet to filter the dropdown which will be another challenge. But I've got my beautiful view to show data I've already got in the DB. But the dropdown that should show the Fund's or Coinvestor's name is mixing up things: it will show the name of Coinvestor with ID == 1 even if the investment was made by a Fund.
I thought of making one of the models to have a custom ID such as f1, f2, f3 ... instead of 1, 2, 3... so the system wouldn't mix them. But it seems that it would generate other big compatibility issues.
Do you guys have any other idea?
I wouldn't alter the id column (i.e. I wouldn't change it from an auto-incrementing integer), but because you're mixing two lists in the DB into a single list in the UI you will need some way to note which table each item in the UI came from. For that, sure, use whatever ID scheme you want and then use that differentiating ID as the way to lookup the relevant item.
Also, if you're not going to use the auto-incrementing id columns in the UI (for links or whatever), then you could also just remove them and replace them with your custom identification scheme. There's no reason, for example, that you couldn't assign them all a random 8-digit number, ensuring that number is unique across the different types you're going to put into the list, and then using that id in the UI. It seems that the real issue you're running into is how to combine the lists where ids might overlap, and perhaps it may be feasible for you to devise a way to assign a non-overlapping ID.
Another possibility for assigning non-overlapping IDs, without having to come up with your own scheme or checking for uniqueness across multiple tables is to use a UUID for the lookup ID in the UI drop-down.
I don't get why I'm getting this error
undefined method `sector_id' for #<Portfolio:0x007fe17c2e3848>
I have a Portfolio Model and a Sector model, they look like so
class Portfolio < ActiveRecord::Base
belongs_to :sector
attr_accessible :overview, :title, :sector_id
end
class Sector < ActiveRecord::Base
has_many :portfolios
attr_accessible :name
end
My routes
resources :portfolios do
resources :sectors
end
So within my form to create a new portfolio I have this collection_select
<%= f.label :sector_id, "Choose Sector", :class => 'title_label' %><br>
<%= f.collection_select(:sector_id, Sector.all, :id, :name, :prompt => "Please Select a Sector") %>
This is something I've done many times before and it has worked, can anyone see why I would be getting this error?
The only thing I can think of is that I have called my controller for portfolio as Portfolios, I always get mixed up with plural and singular controller names, would this make a difference in my case?
Maybe you have not run the migration yet that adds the column "sector_id" in your table "portfolios". If you are using MySQL connect to your database and check the table (show create table portfolios;). Use appropriate method to get this info from your database server if you are using other rdbms. Alternatively, in your rails console (rails c) type in Portofolio and see what attributes it prints out. Does it include sector_id?
I am trying to auto populate a select box in rails with a relational table.
Venture_Users has a list of Users and Venture ID's so I want to find all Users under a specific Venture and then display the users via user_id, and user.name.
I tried the following
<%= f.collection_select(:user_id, VentureUser.find_all_by_venture_id(#venture.id), :user_id, :name) %>
However the last attribute :name doesn't work because it is not directly in my results and I need to run a query on my user table to get the name of the user.'
Essentially what I need to but don't know how to do is modify my VentureUsers.find_all statement to join attributes from my user table.
Thanks,
Mike
This should be quite straight forward as long as you have your associations set correctly. If I have understood your scenario correctly then you should probably have it set up like this:
class Venture < ActiveRecord::Base
has_many :venture_users
has_many :users, :through => :venture_users
end
class VentureUser < ActiveRecord::Base
belongs_to :venture
belongs_to :user
end
If your associations indeed look like this, then you should be able to create the select like this:
<%= f.collection_select(:user_id, #venture.users, :id, :name) %>
I'm new to Rails 3, i'm creating a web app that use active admin, i get a problem with him, and asked for help inside github plugin, someone told me maybe a relationship definitions.
I really dont know what is that, i have nested elements and in active admin i want to make nested element independent.
but now, im totally lost. what i missed? thanks.
here is my model definition
class Company < ActiveRecord::Base
before_save :getsubdomain
has_attached_file :logo, :styles => { :thumb => '150x150>', :medium => '250x250>', :normal => '350x350>'}
has_many :buildings
accepts_nested_attributes_for :buildings
end
Building model
class Building < ActiveRecord::Base
belongs_to :companies
end
in my db, i have colum company_id in buildings table.
Here the error message i get..
NameError in Admin/buildings#index
Showing /Library/Ruby/Gems/1.8/bundler/gems/active_admin-c3a1ffa98072/app/views/active_admin/resource/index.html.arb where line #1 raised:
uninitialized constant Building::Companies
Rails.root: /Users/username/Sites/myapps
Request
Parameters:
{"order"=>"id_desc"}
Response
Headers:
None
thanks for your help
belongs_to expects a singular name. Try
belongs_to :company