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Test App This app contains following feature as follow : Articles
- Create New Articles
- Update Articles
- Destroy Articles
- Show Articles
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Blog App
Model name: Article, class: Article -> Capitalized A and singular
File name: article.rb -> singular and all lowercase
Controller file name: articles_controller.rb, class: ArticlesController -> camel case class name, snake case file name both plural
Views folder: articles
Table name: articles -> plural of model
Model name: User, class: User -> Capitalized U and singular
File name: user.rb -> singular and all lowercase
Controller file name: users_controller.rb, class: UsersController -> camel case class name, snake case file name both plural
Views folder: users
Table name: users -> plural of model
To generate a migration to create a table (in this example articles):
rails generate migration create_articles
To add attributes for the table in the migration file, add the following inside create_table block:
t.string :title
t.text :description
t.timestamps
To run the migration file and create the articles table:
rake db:migrate
OR
bundle exec rake db:migrate
If using Rails 5 -> rails db:migrate
To rollback a migration (undo the last migration):
rake db:rollback
If using Rails 5 -> rails db:rollback
To add a column (example: created_at column) to the articles table:
rails generate migration add_created_at_to_articles
Then within the def change method in the migration file:
add_column :articles, :created_at, :datetime
To add a different column (example: name) to a users table:
rails generate migration add_name_to_users
Then within the def change method in the migration file:
add_column :users, :name, :string
In the above two adding column methods, the first argument is the name of the table, second is the attribute name and third is the type
To create a model file for Article:
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In the app/models folder create a file called article.rb
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Fill it in with the following ->
class Article < ActiveRecord::Base
end
If using Rails 5 ->
class Article < ApplicationRecord
end
To start the rails console:
rails console
To test connection to the articles table:
Article.all # classname.all will list all the articles in the articles table
Then simply type in Article (classname) to view the attributes
To create a new article with attributes title and description:
article = Article.new(title: "This is a test title", description: "This is a test description")
article.save
OR
article = Article.new
article.title = "This is a test title"
article.description = "This is a test description"
article.save
Another method to do the same:
article = Article.create(title: "This is a test title", description: "This is a test description") # This will hit the table right away without needing the article.save line
Edit, Delete and Validations - Text directions and code
To find an article with id 2 and edit it's title:
article = Article.find(2) # Here assumption is article with id of 2 was being looked for
article.title = "This is an edited title"
article.save
To delete an article, example with id 5:
article = Article.find(5)
article.destroy
To add validations presence and length validations to article model for title and description:
class Article < ActiveRecord::Base
validates :title, presence: true, length: {minimum: 3, maximum: 50}
validates :description, presence: true, length: {minimum: 10, maximum: 300}
end
If using Rails 5, the first line above would be -> class Article < ApplicationRecord
To find errors in article object while saving (if it's rolled back):
article.errors.any?
article.errors.full_messages
Create New Articles from UI - Text directions and code
In the config/routes.rb file add the following line to add all the routes for articles:
resources :articles
This will add the following routes:
routes path HTTP verb link controller#action
articles index articles GET /articles articles#index
new article new_article GET /articles/new articles#new
create article POST /articles articles#create
edit article edit_article GET /articles/:id articles#edit
update article PATCH /articles/:id articles#update
show article article GET /articles/:id articles#show
delete article DELETE /articles/:id articles#destroy
To create articles controller with a new action, under app/controllers create a file named articles_controller.rb (snake case):
class ArticlesController < ApplicationController
def new
@article = Article.new
end
end
To create a view, under app/views create a folder named articles and within it create a file named new.html.erb then fill in the following:
<%= form_for @article do |f| %>
<%= f.label :title %>
<%= f.text_field :title %>
<%= f.label :description %>
<%= f.text_area :description %>
<%= f.submit %>
<% end %>
Create action and private article_params method for string parameters in the articles controller (Note: This is not complete):
def create
@article = Article.new(article_params)
@article.save
redirect_to article_path(@article)
end
private
def article_params
params.require(:article).permit(:title, :description)
end
Complete New and Show Actions - Text directions and code
Completed create action in articles controller:
def create
@article = Article.new(article_params)
if @article.save
flash[:notice] = "Article was successfully created"
redirect_to article_path(@article)
else
render 'new'
end
end
Flash message code added to application.html.erb under app/views/layouts folder (right under and above <%= yield %>:
<% flash.each do |name, msg| %>
- <%= msg %>
<% end %>
Code added to display errors in the new.html.erb template under app/views/articles folder:
<% if @article.errors.any? %>
- <%= msg %>
<% @article.errors.full_messages.each do |msg| %>
<% end %>
<% end %>
To create the show action, add the following show method to articles_controller.rb file:
def show
@article = Article.find(params[:id])
end
To create the show view, add a show.html.erb file under the app/views/articles folder and fill in the code:
Title: <%= @article.title %>
Description: <%= @article.description %>
***************************************************************************************************************** Edit Articles - Text directions and code Route for editing articles takes the form ->/articles/:id/edit
Edit action in the articles controller:
def edit
@article = Article.find(params[:id])
end
Update action in the articles controller:
def update
@article = Article.find(params[:id])
if @article.update(article_params)
flash[:notice] = "Article was successfully updated"
redirect_to article_path(@article)
else
render 'edit'
end
end
To create edit template, create a file named edit.html.erb under the app/views/articles folder and fill in the following code:
<% if @article.errors.any? %>
- <%= msg %>
<% @article.errors.full_messages.each do |msg| %>
<% end %>
<% end %>
<%= form_for @article do |f| %>
<%= f.label :title %>
<%= f.text_field :title %>
<%= f.label :description %>
<%= f.text_area :description %>
<%= f.submit %>
<% end %>
List Articles and Layout Links - Text directions and code Section 4, Lecture 87 To create listings index first add the index action to acticles controller:
def index
@articles = Article.all
end
Create the view file index.html.erb under app/views/articles folder:
<%= link_to "Create new article", new_article_path %>
<% @articles.each do |article| %>
<% end %>
| Title | Description | ||
|---|---|---|---|
| <%= article.title %> | <%= article.description %> | <%= link_to 'Edit', edit_article_path(article) %> | <%= link_to 'Show', article_path(article) %> |
Then update the views with links ->
show.html.erb:
Title: <%= @article.title %>
Description: <%= @article.description %>
<%= link_to "Edit this article", edit_article_path(@article) %> |
<%= link_to "Back to articles listing", articles_path %>
Add the back to articles listing path to the bottom of both new.html.erb and edit.html.erb pages:
<%= link_to "Back to articles listing", articles_path %>