Group 1

Answer.md

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+
+
+# Example:
+class User
+  attr_accessor :name, :email, :phonenumber, :type, :activated
+  has_one :profile
+  has_many :articles
+
+  def get_user_information
+    puts "Name: " + self.name
+    puts "Phonenumber: " + self.phonenumber
+  end
+
+  def activated_user
+    User.where(activated: true)
+  end
+
+  def get_user_type
+    user.type
+  end
+
+  def create_new_user(name, email, phonenumber, type = 'developer', activated = false)
+    user = User.new
+    user.name = params[:user][:name],
+    user.email = params[:user][:email],
+    user.phonenumber: params[:user][:phonenumber],
+    user.type = params[:user][:type]
+    user.activated = params[:user][:activated]
+    if user.save
+      render json: {
+        name: user.name,
+        phonenumber: user.phonenumber,
+        email: user.email
+      }, status: 200
+    else
+      render json: {
+        message: "There has been an error while trying to create user"
+      }, status: 402
+    end
+  end
+
+
+  def edit_user(name, email, phonenumber)
+    user = User.find_by(id: params[:id])
+    user.email = email
+    user.name = name
+    user.phonenumber = phonenumber
+    if user.save
+      render json: {
+        name: user.name
+        phonenumber: user.phonenumber
+        email: user.email
+      }, status: 200
+    else
+      render json: {
+        message: "There has been an error while trying to create user"
+      }, status: 402
+    end
+  end
+end
+# 1. The "User" class is too large, it is not only responsible for displaying
+# user data, but also responsible for creating a new user and editing user.
+# We should use "Extract Class" to make this class smaller
+# (User controller for example)
+# 2. The method "create_new_user" uses too many parameter. The parameters
+# should be extract into another method call or parameter object,
+# using rails's built in helper called strong parameter
+# 3. The methods create_new_user and edit_user are too long,
+# (more than 10 lines). We can refactor these methods by using
+# the "Extract methods" technique, by seperating method calls inside
+# each main method and encapsulate them in private
+# 4. The parameter "name", "email", "method" appears many time accross
+# the method create_new_user and edit_user, making this a "Data clump" smell.
+# Fix this simply by using strong parameters as above
+
+# Fix:
+class User
+    attr_accessor :name, :email, :phonenumber, :type, :activated
+  has_one :profile
+  has_many :articles
+
+  def get_user_information
+    puts "Name: " + self.name
+    puts "Phonenumber: " + self.phonenumber
+  end
+
+  def activated_user
+    User.where(activated: true)
+  end
+
+  def get_user_type
+    user.type
+  end
+end
+
+class UserController
+  def create_new_user
+    user = User.new(user_params)
+    user.save ? response_user_data : response_fail
+  end
+
+  def edit_user
+    user = User.find_by(id: params[:id])
+    user.update_attributes(user_params) ? render_user_data : response_fail
+  end
+
+  private
+
+  def user_params
+    params.require(:user).permit(:name, :phonenumber, :email, :type, :activated)
+  end
+
+  def assign_user_attributes args
+
+  end
+
+  def render_user_data user
+    render json: {
+      name: user.name
+      phonenumber: user.phonenumber
+      email: user.email
+    }, status: 200
+  end
+
+  def response_fail
+    render json: {
+      message: "There has been an error while trying to create user"
+    }, status: 402
+  end
+end
+
+#Example:
+
+class Manager
+  def edit_user user
+    user.update_attributes(user_params)
+  end
+
+  def delete_user user
+    user.destroy
+  end
+end
+
+class Admin < Manager
+end
+
+class Moderator < Manager
+end
+
+# 5. The class moderator here can not have access to the method "delete_user"
+# because only admin can delete an user. So this is "Refused Bequest" smell and
+# it can be fixed by delegating only the method used to moderator class
+# After that, only the "edit_user" method can be used for Moderator
+
+class Moderator < Manager
+  def_delegators :edit_user
+end
+
+
+#Example:
+
+class CreatePicture < ActiveRecord::Migration[5.0]
+  def change
+    create_table :pictures do |t|
+      t.string :name
+      t.string :description
+      t.color :string
+
+      t.timestamps
+    end
+  end
+end
+
+# 6. This is an example of code smell "Primitive Obssession",
+# as using the String data type to store color code in hexadecimal
+# can be dangerous because string input is not validated,
+# such as "324UFA" or "FF3FF3FF2" are not valid hexadecimal color code.
+
+# Fix:
+class Picture
+  has_one :color
+end
+
+class Color
+  belongs_to :picture
+
+  attr_reader :code
+
+  def initialize(code)
+    @code = validate(code)
+  end
+
+  def to_s
+    @code.to_s
+  end
+
+  private
+
+  def validate(code)
+    raise "Invalid color code" unless code =~ /[0-9A-Fa-f]{6}/
+    code
+  end
+end
+
+
+# Example:
+class Article
+  attr_accessor :vote, :view_count, :share_count
+  belongs_to :user
+end
+
+class User
+  has_many :articles
+
+  def popularity
+    count = 0
+    self.articles.each do |article|
+      count += article.vote + article.view_count + article.share_count
+    end
+
+    count
+  end
+end
+
+# 7. This example smells of "Feature Envy". The "User" class has method "popularity" to determine
+# popularity based on all articles statistics. But inside "User" class the data from "Article" class
+# is called too many times
+
+#Fix:
+
+class Article
+  belongs_to :user
+  attr_accessor :vote, :view_count, :share_count
+
+  def article_popularity
+    vote + view_count + share_count
+  end
+end
+
+class User
+  has_many :articles
+  def popularity
+    count = 0
+    self.articles.each do
+      count += articles.article_popularity
+    end
+    count
+  end
+end
+
+