Ruby on Rails Kickstart 103 & 104

Ruby on Rails Kickstart 103 & 104.
Presentation file for NCCU Trend Tech Club.

Transcript

1. Ruby on Rails #103 Scaffold and modify scaffold
2. Scaffold Ruby on Rails magic
3. Getting started 1. Ruby on Rails command 2. Generate an article scaffold • MVC pattern 3. Synchornize database schema • ORM 4. Modify scaffold
4. Ruby on Rails Command rails generate scaffold scaffold_name field1_name:field1_type \ field2_name:field2_type ... fieldN_name:fieldN_type • Replace scaffold_name with actual scaffold names • Replace field1_name to fieldN_name with actual field names
5. Ruby on Rails command (Cont.) field1_type to fieldN_type needs to be a valid data type source: https://ihower.tw/rails4/migrations.html#section
6. Generate an article scaffold rails generate scaffold article title:string body:text The command generates... • a controller handles requests from clients and transfer data between models and views • a model with one string field called title and one text field body called article • a form for create and update articles and several views to list articles and to display single article
7. Controller? Model? View? What the hell are they?
8. MVC pattern
9. Models and views DO NOT directly exchange data Remember this till the Apocalypse
10. Synchronize database schema rake db:migrate • rake runs scripts called Rakefile. Rakefile holds a bundle of commands related to Ruby on Rails but not part of Ruby on Rails • db:migrate: synchronize database schema, as known as database migration • tmp:clear: clean temporary files
11. Why bothered? In PHP $title = mysql_real_escape_string($_POST['title']); $body = mysql_real_escape_string($_POST['body']); $sql = "INSERT INTO `articles` (`title`, `body`)" . " VALUES ('{$title}', '{$body}')"; mysql_query($sql);
12. Sucks Just one SQL injection can make your system upside down ONE SQL INJECTION!
13. Don't bother In Ruby on Rails # params[:article] = { # title: 'Article title', # body: 'Article body' # } article = Article.new(params[:article]) article.save ORM saves the day
14. ORM Object Relational Mapping
15. ORM (Cont.) • Object Relational Mapping • Object stands for objects in Ruby on Rails • Relational stands for relational database system, such as MySQL, PostgreSQL, Microsoft SQL Server...etc. • Mapping stands for the procedure transfer data structure into table row
16. Start web server If you forget how to do so, feel free to take a look on #101
17. Open browser https://[your-cloud9-preview-url]/articles If you see this, you got it
18. Just one command ...fulfills fundamental needs
19. Modify scaffold Add / Remove a field Nobody is perfect
20. Add a field 1. Modify model 1. Create a database migration 2. Synchronize database schema 2. Modify the controller 3. Modify views
21. Create a database migration rails generate migration \ add_author_to_articles author:string • Replace author with field name you want to add • Replace articles with plural form of model • Replace string with valid data type from the table mentioned before
22. Synchronize database schema rake db:migrate
23. Modify the controller # Only allow a trusted parameter "white list" through. def article_params params.require(:article).permit(:title, :body, :author) end • Append :author to the list of white list
24. Mass-assignment Vulnerability ℂ Github ᤩ hack牧藳 Rails ጱਞ獊௔
25. Strong parameter Only allow values of known keys to be assigned to the ORM object
26. Modify views 1. index view 2. show view 3. _form partial
27. index view ... <td><%= article.body %></td> <td><%= article.author %></td> <td><%= link_to 'Show', article %></td> ...
28. show view ... </p> <p> <strong>Author:</strong> <%= @article.author %> </p> <%= link_to 'Edit', edit_article_path(@article) %> | ...
29. _form partial ... <%= f.input :body %> <%= f.input :author %> </div> ...
30. Five Count of files you edited for adding a field
31. Ruby on Rails magic
32. Remove a field from scaffold 1. Create a database migration 2. Synchronize database schema 3. Modify the controller 4. Modify views
33. Database migration Any changes related to database, including adding or removing fields
34. Create a database migration rails generate migration remove_body_from_articles • Replace author with field name in the model
35. Synchronize database schema That's all I can say
36. Modify the controller Reverse procedure against adding fields
37. Modify views Reverse procedure against adding fields
38. End of Ruby on Rails #103
39. Ruby on Rails #104 Dig into MVC
40. Review
41. Controller 1. Receive requests 2. Fetch raw or processed data from models 3. Inject data into views
42. Controller (Cont.) class SomeController < ApplicationController ... def action_name ... end ... end
43. Controller (Cont.) 1. One controller has many actions 2. Each action has its own purpose 3. Actions are isolated to each other 4. One action takes care of one request
44. Model 1. Query rows from database 2. Process data 3. Write data into database
45. Model (Cont.) class Person def full_name first_name + last_name end end
46. Model (Cont.) 1. Model DOES NOT hold fields, schema DOES 2. Model is a class 3. In ORM, fields would be mapped as properties in object, thus we can manipulate them via methods
47. Model (Cont.) • HumanBeing : Model • Person : Object • People : Iterable object (a.k.a. array) of objects
48. Model (Cont.) @all_people = HumanBeing.all @adults = HumanBeing.where('age >= ?', 20) @person = HumanBeing.find_by(identity: 'A123456789')
49. Views 1. Build HTML documents 2. Respond to clients
50. Views (Cont.) Full name: <%= @person.full_name %> Where does @ point to?
51. Views (Cont.) 1. Symbol @ points to corresponding controller in views 2. DO NOT conduct complicated calculations or property access in views 3. Views should have only if and each statements
52. Homework 1. Create a scaffold from scratch 2. Add a field to the scaffold 3. Remove a existing field from the scaffold