I have my resources:
resources :flows do
resources :fmodules
end
the new method in fmodules controller:
# /flows/1/fmodules/new
def new
#flow = Flow.find(params[:flow_id])
#fmodule = #flow.fmodules.build
end
the models:
class Flow < ApplicationRecord
has_many :fmodules, dependent: :destroy
validates :code, presence: true, length: { maximum: 5 }
validates :name, presence: true
end
class Fmodule < ApplicationRecord
belongs_to :flow
end
When i try to go at /flows/1/fmodules/new ruby says unknown attribute 'flow_id' for Fmodule.
I dont know what is wrong
Here is the migration of Fmodel in addition
class CreateFmodules < ActiveRecord::Migration[5.1]
def change
create_table :fmodules do |t|
t.string :code
t.string :name
t.string :f_code
t.timestamps
end
add_foreign_key :fmodules, :flows, column: :f_code
end
end
So, the problem is that you don't have a flow_id in your fmodules table. In rails, by convention the foreign key is build automatically inferring column name from an argument you pass to belongs_to. That's why rails think that foreign key for flows table is flow_id and it raises exception not finding it. You can overwrite the default with foreign_key option like the following
class Fmodule < ApplicationRecord
belongs_to :flow, foreign_key: : f_code
end
Related
I'm building a sinatra app with Active record. The idea is to essentially have a custom email app. Here I have the models User and Message. A User has_many :messages and a Message belongs_to :user. This may be where I have the issue. I also have it set up for a Message belongs_to :user and has_many :users.
here are the models
Now when I create a message in the action controller I am attempting to use the shove methods to put the new message in a user's messages array. If I attempt to "share" this message with multiple users at once with all the user's id's in params( #user = User.find(id) and then user.messages << #new_message) the last user will have the message stored in it's .messages array. However only the last one to be iterated.
class Message < ActiveRecord::Base
belongs_to :user
has_many :users
end
class User < ActiveRecord::Base
validates :username, presence: true, uniqueness: true
has_secure_password
has_many :messages
end
The idea is the writer "owns" the message but can share it with many users. Here are the tables
class CreateUsers < ActiveRecord::Migration
def change
create_table :users do |t|
t.string :username
t.string :email
t.string :password_digest
end
end
end
class CreateMessages < ActiveRecord::Migration
def change
create_table :messages do |t|
t.string :message
t.string :author
t.integer :user_id
t.integer :user_ids
t.integer :share_id
t.string :title
t.timestamps
end
end
end
# action controller
new_params = {}
new_params[:message] = params["message"]
new_params[:title] = params["title"]
new_params[:author] = params["author"]
new_params[:user_id] = params["user_id"]
#message = Message.create(new_params)
# #share = Share.create
# #message.share_id = #share.id
response.map do |x|
x.messages << #message
x.save!
end
#all = User.all
#user = User.find_by(username: #message.author)
erb :"/user/sent"
I am fairly sure this is because my associations are not set up properly.
You need to have has-and-belongs-to-many relationship between users and messages to implement sharing multiple messages to multiple users. Create an additional record, e.g. MessageShare and do has many to it from both sides:
class MessageShare < ActiveRecord::Base
belongs_to :user
belongs_to :message
end
class Message < ActiveRecord::Base
has_many :message_shares
end
class User < ActiveRecord::Base
has_many :message_shares
end
message_shares table should have user_id and message_id integer columns.
i'm learning Rails and i'm doing an exercise to practice associations and migration files.
Currently, trying to make a models between users, auction item, and bids.
So far for the migrate files I have the following:
class CreateItem < ActiveRecord::Migration
def change
create_table :auction do |t|
t.string :item_name
t.string :condition
t.date :start_date
t.date :end_date
t.text :description
t.timestamps
end
end
end
class CreateBids < ActiveRecord::Migration
def change
create_table :bids do |t|
t.integer :user_id
t.integer :auction_id
t.timestamps
end
end
end
class CreateUsers < ActiveRecord::Migration
def change
create_table :users do |t|
t.string :email
t.string :username
t.string :password_digest
t.timestamps
end
end
end
These are the following models:
class Bid < ActiveRecord::Base
belongs_to :bidder, class_name: "User", foreign_key: "bidder_id"
belongs_to :auction
end
class User < ActiveRecord::Base
has_many :bids
has_many :auctions, :foreign_key => 'bidder_id'
has_secure_password
end
class Auction < ActiveRecord::Base
belongs_to :seller, class_name: "User", foreign_key: :user_id
has_many :bids
has_many :bidders, through: :bids
end
Any suggestions or opinions? I'm currently trying to test the tables but auctions doesn't seem to be working...
Specifically, my auction table can't seem to find a user_id and therefore a user doesn't have any auctions.
foreign_key refers to the _id (by default) or any unique attribute used to associate the models.
I can't see bidder model, you need to replace them with user_id as they are associated to user model.
Refer for more details belongs_to
class CreateBids < ActiveRecord::Migration
def change
create_table :bids do |t|
t.integer :user_id **do not think this is correct**
t.integer :auction_id **or this one**
t.timestamps
end
end
end
You want to use something more along the lines of the following
class CreateGames < ActiveRecord::Migration[5.0]
def change
create_table :games do |t|
t.integer :total_time
t.references :version, foreign_key: true **#this is how a foreign key should be declared**
t.integer :total_points
t.timestamps
end
end
end
Alternatively, if you want to change things in future migrations you can always add a reference:
def change
add_reference :levels, :version, foreign_key: true
end
I'm new in Ruby on Rails. I don't understand how rails behave using foreign Key, I've researched it for some days but I didn't get the answer.
Simple sample:
I created two tables:
class CreatePosts < ActiveRecord::Migration
def change
create_table :posts do |t|
t.string :title
t.text :content
t.timestamps null: false
end
end
end
class CreateComments < ActiveRecord::Migration
def change
create_table :comments do |t|
t.string :author
t.text :content
t.references :post, index: true, foreign_key: true
t.timestamps null: false
end
end
end
My models are:
class Post < ActiveRecord::Base
has_many :comments
end
class Comments < ActiveRecord::Base
belongs_to :post
end
My doubt is: As I have a Foreign Key in my table COMMENTS (.references :post, index: true, foreign_key: true) I guess that I wouldn't be able to destroy any post which has any COMMENTS associated to them, isn't it ?
I did as above but I am still able to destroy the posts, even when I have the comments associated. How can I treat it? What am I doing wrong?
Cheers
I'd refine your migrations to use the :on_delete options on your foreign keys. It can take one of those values : :nullify, :cascade, :restrict
From what I understand, you need to set this value to :restrict on your post_id column in your comments table, so that posts with associated comments can't be deleted.
Update:
Or, you could also directly set it on the association in your Post model:
has_many :comment, dependent: :restrict_With_error
Please take a look at:
http://api.rubyonrails.org/classes/ActiveRecord/ConnectionAdapters/SchemaStatements.html#method-i-add_foreign_key
http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html#method-i-has_many -> See the Options: Section
From what i understand, you dont want to destroy a post if there are associated comments?
Why not put a if statement encapsulating the delete button for a post
So something like:
psudo code
if #post.comments exists
cant delete post
else
delete post
end
I have two models Classification and ClassificationRelationships. I want to create a hierarchy of classifications using supperclass and subclass so that each classification can have many subclasses but only one superclass.
my migrations look like this
class CreateClassifications < ActiveRecord::Migration[5.0]
def change
create_table :classifications do |t|
t.string :symbol
t.string :title
t.integer :level
t.timestamps
end
add_index :classifications, :symbol
add_index :classifications, :level
end
end
class CreateClassificationRelationships < ActiveRecord::Migration[5.0]
def change
create_table :classification_relationships do |t|
t.integer :superclass_id
t.integer :subclass_id
t.timestamps
end
add_index :classification_relationships, :superclass_id
add_index :classification_relationships, :subclass_id
add_index :classification_relationships, [:superclass_id, :subclass_id], unique: true, name: 'unique_relationship'
end
end
so far with my models I have
class ClassificationRelationship < ApplicationRecord
belongs_to :superclass, :class_name => "Classification"
belongs_to :subclass, :class_name => "Classification"
end
class Classification < ApplicationRecord
has_many :classification_relationships
has_many :subclasses, through => :classification_relationships
has_one :superclass, through => :classification_relationships
end
I read quite a few other posts but am still unsure how to finish the associations. I am pretty sure I need to specify the foreign keys but am not clear on how I should do that. Thanks for the help!
Get rid of ClassificationRelationship.
All you need is for Classification to have a parent_id which, in the root instances, is allowed to be null.
Add:
belongs_to :parent, class_name: 'Classification', foreign_key: :parent_id
def children
Classification.where(:parent_id => self.id)
end
Some operations will not be optimal. e.g. Find all descendants. That's because this will require repeated queries to find children, their children, etc...
This may not be a concern for you.
If it is, I recommend storing a path as such:
after_create :set_path
def set_path
path = parent ? "#{parent.path}#{self.id}/" : "#{self.id}/"
self.update_attributes!(:path => path)
end
Then you can do things like:
def descendants
Classification.where("classifications.path LIKE '#{self.path}%' AND classifications.path <> '#{self.path}'")
end
Of course, make sure path is indexed if you'll be doing queries like that.
I've the following two models:
class Dispute < ApplicationRecord
belongs_to :accuser, class_name: 'User', optional: true
belongs_to :defendant, class_name: 'User', optional: true
end
class User < ApplicationRecord
end
Here's the migration for Dispute:
class CreateDisputes < ActiveRecord::Migration[5.0]
def change
create_table :disputes do |t|
t.references :accuser
t.references :defendant
end
end
end
This is how they behave in Rails:
Dispute.first.accuser
# => <# User>
Dispute.first.defendant
# => <# User>
In Sequel, I'm supposed to use many_to_one, but does that mean that Sequel User model should have a corresponding one_to_many? Can't seem to get it to work.
This should work:
Sequel.migration do
change do
create_table(:disputes) do
primary_key :id
foreign_key :accuser_id, :users
foreign_key :defendant_id, :users
end
end
end
class Dispute < Sequel::Model
many_to_one :accuser, :class=>:User
many_to_one :defendant, :class=>:User
end