I need to implement activeuuid gem to have UUIDs instead of default Rails ids. we can implement it for creating new migration as:
class CreateStudents < ActiveRecord::Migration
def change
create_table :students, :id => false do |t|
t.uuid :id, :primary_key => true
t.string :name
t.string :email
t.timestamps
end
end
end
And in model we include ActiveUUID::UUID as:
class Student < ActiveRecord::Base
attr_accessible :email, :name
include ActiveUUID::UUID
end
Now I already have a database so how can I implement the activeuuid gem to have UUIDs instead of default Rails ids for existing DB?
Need to make changes in all migrations or what?
Need help in this regard. thanks
The UUID is stored as a binary field w/ 16 positions as I found here: https://github.com/jashmenn/activeuuid/blob/master/lib/activeuuid/patches.rb#L62
It worked for me (existing table without records):
def change
reversible do |dir|
change_table :payments do |t|
dir.up { t.change :id, :binary, limit: 16, :primary_key => true }
dir.down { t.change :id, :integer }
end
end
end
Don't forget to add those lines to your model as well:
include ActiveUUID::UUID
natural_key :at_least_one_field_here
More info in the github repo: https://github.com/jashmenn/activeuuid/
Related
I am new in Ruby on Rails and I am trying to make a book registration website. Everything works fine except category section. When a user assign a category to his book, my database copies book_categories.id and put it in book.book_categories_id. The website also have a profile page, where you can view user's book(s). My problem is to display a category.name, I searched a lot of similar problems but I have not found the right answer.
Here is my book controller:
before_action :set_book, except: [:index, :new, :create]
before_action :authenticate_user!, except: [:show]
def show
#photos = #book.photos
end
def index
#books = current_user.books
end
def new
#book = current_user.books.build
end
def create
#book = current_user.books.build(books_params)
if #book.save
redirect_to listing_book_path(#book), notice: "Saved."
else
flash[:alert] = "Failed."
render :new
end
end
private
def set_book
#book = Book.find(params[:id])
end
def book_params
params.require(:book).permit(:book_categories_id, :book_name, :summary, :address, :price, :company_name)
end
As long as I understand, I have to allow my controller to have access to my category table but I do not know how. Also, all of my categories store in seed.rb.
This is my BookCategory.rb model:
class BookCategory < ActiveRecord::Base
has_many :books, :foreign_key => :book_categories_id
end
Book.rb model:
class Book < ApplicationRecord
belongs_to :user, :foreign_key => 'user_id'
has_many :photos, dependent: :delete_all
validates :book_name, presence: true
validates :book_categories_id, presence: true
def cover_photo
if self.photos.length > 0
self.photos[0].image.url
else
"default/image-default.jpg"
end
end
end
My schema.rb:
create_table "book_categories", force: :cascade do |t|
t.string "name"
t.string "subcategory"
t.text "description"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
end
create_table "book", force: :cascade do |t|
t.string "book_name"
t.text "summary"
t.string "address"
t.decimal "price", precision: 8, scale: 2
t.boolean "active"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.integer "user_id"
t.float "latitude"
t.float "longitude"
t.string "company_name"
t.integer "book_categories_id"
t.index ["book_categories_id"], name: "index_books_on_book_categories_id"
end
Usually, when I type #book_categories.name, I get an error:
undefined method `name' for nil:NilClass
And at the very end, it says Parameters: {"id"=>"15"} whereas the category.id is different, and it passes book.id instead.
What I am doing wrong?
First fix the naming problem you have going. I don't know how the books table got called "book" instead of "books" in the schema, but you might have to fix that first.
Then category should be singular everywhere except the database table name. You need to make a migration to fix the foreign key and its index in the books table something like this:
class FixCategoryNaming < ActiveRecord::Migration
def change
remove_column :books, :book_categories_id
add_reference :books, :book_category, index: true, foreign_key: true
end
end
Then run rails db:migrate and check the schema looks ok
Then in the BookCategory class change the line to simply
has_many :books
You need to add this line to your Book class
belongs_to :book_category
and change the validation for book_category to be this
validates :book_category_id, presence: true
Then in the view for book index you have a #books variable. You can get the book name and category name for each book like this:
<% #books.each do |book| %>
<p><%= book.book_name %></p>
<p><%= book.book_categories.name %></p>
<% end %>
I think you need to setup as has_many through relationship. This is a good place to start http://guides.rubyonrails.org/association_basics.html#the-has-many-through-association
I am trying to add user:references onto my already existing model. This is what I originally wrote:
rails g model Post title:string description:text
I do this to add the user:references by running rails generate migration add_user_to_posts user:references, I am receiving this error upon running rake db:migrate:
-- create_table(:users)
rake aborted!
StandardError: An error has occurred, this and all later migrations canceled:
SQLite3::SQLException: table "users" already exists
I am reading the error and I understand I already have a User model, however, I want to add this attribute to the Post model, not the User model.
Db file:
Posts:
class CreatePosts < ActiveRecord::Migration[5.0]
def change
create_table :posts do |t|
t.string :title
t.text :description
t.timestamps
end
end
end
Trying to add the user to posts:
class AddUserToPosts < ActiveRecord::Migration[5.0]
def change
add_reference :posts, :user, foreign_key: true
end
end
Users:
class CreateUsers < ActiveRecord::Migration[5.0]
def change
create_table :users do |t|
t.string :name
t.string :uid
t.string :avatar_url
t.timestamps
end
add_index :users, :uid
end
end
However, rake db:migrate gives me the error above.
iam working in rails 3.while trying to creating a user i am getting
cant mass assign the protected attributes error
I included following gems in the gemfile
gem 'authlogic'
gem 'gemcutter'
and run bundle install in rails console
then create a a user model and add the required authlogic columns to the migration.
class CreateUsers < ActiveRecord::Migration
def change
create_table :users do |t|
t.string :login, :null => false
t.string :crypted_password, :null => false
t.string :password_salt, :null => false
t.string :persistence_token, :null => false
t.timestamps
end
end
end
and did rake db:migrate
Included authlogic in the user model.
# /app/models/user.rb
class User < ActiveRecord::Base
acts_as_authentic
end
while trying to create a user in rails console User.create(name: "pria",password: "priya123", password_confirmation: "priya123")
iam getting
cant mass assign the protected attributes :name, :password, :password_confirmation
How can i rectify this error!
In your User model:
attr_accessible :name, :password, :password_confirmation
You must add these attributes to the attr_accessible list in your model.
For important information about mass-assignment and its security implications: http://guides.rubyonrails.org/security.html#mass-assignment
Is there a way to specify a database level uniqueness constraint on a field in a Rails 3.1+ migration? I know ActiveRecord's validates_uniqueness_of would work, but I'm curious to know if this can be specified elsewhere.
For example, in order to specify that the 'login' field should be unique in a migration such as ...
class CreateUsers < ActiveRecord::Migration
def change
create_table :users do |t|
t.string :name
t.string :login
t.timestamps
end
end
end
... I'd like to add an option like :unique => true.
There's nothing mentioned in the Documentation so I assume that's not a great place/way to do things, but does anyone know how this might be achieved (even if it's manually added to the resulting schema)? Or is validates_uniqueness_of the preferred way to go?
You can add unique index so:
def change
create_table :users do |t|
t.string :name
t.string :login
t.timestamps
end
add_index :users, :login, :unique => true
end
I have a Model called Challenge that is created by a User. It has a Difficulty associated with it as well. When I create the Challenge and hand it the Author (User) and Difficulty, the Difficulty associate works, but the Author (User) one doesn't. The weirdest part is, when you look at the Challenge object, it shows the Author key its associated with.
challenge = Challenge.first
challenge.author (prints Nil) #Doesn't even run a Query
When I create a Challenge using the following code, the user_id is Nil.
user = User.find(1)
diff = Difficulty.find(1)
Challenge.create(:author => user, :difficulty => diff, :title => "My Challenge")
When I create a Challenge using this code, the User gets the relation to the Challenge and the Challenge gets the user_id of the User. But you can only go from User to Challenge. Challenge to User returns Nil.
user = User.find(1)
diff = Difficulty.find(1)
chall = Challenge.create(:difficulty => diff, :title => "My Challenge")
user.authored_challenges << chall
Here are my Models and Tables
# Models
class User < ActiveRecord::Base
has_many :authored_challenges, :class_name => "Challenge"
attr_accessible :display_name, :authored_challenges
end
class Reward < ActiveRecord::Base
has_many :challenges
attr_accessible :name, :value, :challenges
end
class Challenge < ActiveRecord::Base
belongs_to :reward
belongs_to :author, :class_name => "User"
attr_accessible :title, :description, :reward, :author
end
# Tables
create_table :users do |t|
t.string :display_name
t.timestamps
end
create_table :rewards do |t|
t.string :name
t.float :value
t.timestamps
end
create_table :challenges do |t|
t.integer :user_id
t.integer :reward_id
t.string :title
t.string :description
t.timestamps
end
According to: http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html the foreign key should be:
:foreign_key => :author_id
Don't forget to add the field. Good Luck!
Have you tried:
belongs_to :author, :class_name => "User", :foreign_key => :user_id
From the Rails documentation:
By convention, Rails assumes that the column used to hold the foreign key on this model is the name of the association with the suffix _id added. The :foreign_key option lets you set the name of the foreign key directly
The example given in the docs is very similar to the one you have:
class Order < ActiveRecord::Base
belongs_to :customer, :class_name => "Patron", :foreign_key => "patron_id"
end