Note database.yml can describe database settings RDB is a database that can manage data in tabular format RDBMS is a system that manages RDB, and there is MySQL in RDBMS! !!
A library is a collection of complex functions. Gem information is managed in Gemfile
When describing the contents to be recorded in the database in the migration file
def change create_table :tweets do |t| t.string :name t.text :image end
Described as t. type: Described in the form of column name Use the rails db: migrate command to reflect in the database
-When adding data to the column name created by the flow up to this point Launch console
Tweet.create(name: "takashi", text: "Nice to meet you!")
Now you can save (create) information in the name column and image column of the tweets table created from the Tweet model. → But if you don't specify the record number, you can't save it ... ?? I thought, but it seems that the record number will be 1 without permission
Tweet list display
Define an index action for your controller Write to the routes.rb file
Use the resources method as a method to automatically generate routes to 7 actions
Rails.application.routes.draw.do resources :tweets end
→ The symbol: tweets is specified as an argument of resources. Then, the routing corresponding to the path of/tweets is generated!
Display function In other words, if you want to specify only the index action, write resources: tweets, only :: index
Controller edition
Make a controller named tweets with rails d controller tweets! Edit tweets_controller.rb!
Specify the path of app/controllers/tweets_controller.rb
Describe index action in class TweetsController
def index @tweets = Tweet.all end
→ Now you can assign all the records in the tweets table to the instance variable and send it to the view.
View
Create a file called index.html.erb. View all tweet posts here Use the each method when you want to extract all the information in the tweets table!
@tweets.each do |tweet|
tweet.text tweet.name
end
Now you can extract the information from the text and name columns of the tweets table (by the each method) from all the records and display it on the post list screen!
I omitted all <%%> etc. and described only the important points
About layout templates → Describe the parts that are common to all view files, such as headers and footers. Described in a file called application.html.erb It exists in app/views/layouts/application.html.erb
The description of each view file is aggregated in <% = yield%> in the body element of application.html.erb.
Regarding CSS description → app/assets/stylesheets/application.css Describe in
All the descriptions of ●● .css existing in the file called stylesheets are read into application.css!