Session 2 Editorial

session_2/cricviz/app/models/cricketer.rb

@@ -1,15 +1,15 @@
 class Cricketer < ApplicationRecord
   # Select players from the country 'Australia'
-  scope :australian_players, -> { raise NotImplementedError }
+  scope :australian_players, -> { where(country: 'Australia') }
 
   # Select players with the role 'Batter'
-  scope :batters, -> { raise NotImplementedError }
+  scope :batters, -> { where(role: 'Batter') }
 
   # Select players with the role 'Bowler'
-  scope :bowlers, -> { raise NotImplementedError }
+  scope :bowlers, -> { where(role: 'Bowler') }
 
   # Sort players by the descending number of matches played
-  scope :descending_by_matches, -> { raise NotImplementedError }
+  scope :descending_by_matches, -> { order(matches: :desc) }
 
   # Batting average: Runs scored / (Number of innings in which player has been out)
   #
@@ -19,7 +19,11 @@ class Cricketer < ApplicationRecord
   # - If the player has not batted yet, return nil
   # - If the player has been not out in all innings, return runs scored.
   def batting_average
-    raise NotImplementedError
+    return nil if runs_scored.nil? || innings_batted.nil? || not_out.nil?
+
+    return runs_scored if innings_batted == not_out
+
+    runs_scored.fdiv(innings_batted - not_out)
   end
 
   # Batting strike rate: (Runs Scored x 100) / (Balls Faced)
@@ -29,12 +33,82 @@ def batting_average
   #   data is incomplete
   # - If the player has not batted yet, return nil
   def batting_strike_rate
-    raise NotImplementedError
+    return nil if runs_scored.nil? || balls_faced.nil? || balls_faced == 0
+
+    (runs_scored * 100).fdiv(balls_faced)
   end
 
   # Create records for the classical batters
   def self.import_classical_batters
-    raise NotImplementedError
+    Cricketer.create(
+      name: 'Sachin Tendulkar',
+      country: 'India',
+      role: 'Batter',
+      matches: 200,
+      innings_batted: 329,
+      not_out: 33,
+      runs_scored: 15921,
+      balls_faced: nil,
+      high_score: 248,
+      centuries: 51,
+      half_centuries: 68
+    )
+
+    Cricketer.create(
+      name: 'Rahul Dravid',
+      country: 'India',
+      role: 'Batter',
+      matches: 164,
+      innings_batted: 286,
+      not_out: 32,
+      runs_scored: 13288,
+      balls_faced: 31258,
+      high_score: 270,
+      centuries: 36,
+      half_centuries: 63
+    )
+
+    Cricketer.create(
+      name: 'Kumar Sangakkara',
+      country: 'Sri Lanka',
+      role: 'Wicketkeeper',
+      matches: 134,
+      innings_batted: 233,
+      not_out: 17,
+      runs_scored: 12400,
+      balls_faced: 22882,
+      high_score: 319,
+      centuries: 38,
+      half_centuries: 52
+    )
+
+    Cricketer.create(
+      name: 'Ricky Ponting',
+      country: 'Australia',
+      role: 'Batter',
+      matches: 168,
+      innings_batted: 287,
+      not_out: 29,
+      runs_scored: 13378,
+      balls_faced: 22782,
+      high_score: 257,
+      centuries: 41,
+      half_centuries: 62
+    )
+
+    Cricketer.create(
+      name: 'Brian Lara',
+      country: 'West Indies',
+      role: 'Batter',
+      matches: 131,
+      innings_batted: 232,
+      not_out: 6,
+      runs_scored: 11953,
+      balls_faced: 19753,
+      high_score: 400,
+      centuries: 34,
+      half_centuries: 48
+    )
   end
 
   # Update the current data with an innings scorecard.
@@ -68,14 +142,54 @@ def self.import_classical_batters
   # `ActiveRecord::RecordNotFound` exception with the player's name as
   # the message.
   def self.update_innings(batting_scorecard, bowling_scorecard)
-    raise NotImplementedError
+    batting_scorecard.each do |row|
+      player = Cricketer.find_by(name: row[0])
+
+      raise ActiveRecord::RecordNotFound, row[0] if player.nil?
+
+      player.not_out += 1 if !row[1]
+
+      player.runs_scored += row[2]
+      player.high_score = row[2] if row[2] > player.high_score
+
+      if row[2] >= 100
+        player.centuries += 1
+      elsif row[2] >= 50
+        player.half_centuries += 1
+      end
+
+      player.innings_batted += 1 if row[3]
+      player.balls_faced += row[3]
+
+      player.fours_scored += row[4]
+      player.sixes_scored += row[5]
+
+      player.save
+    end
+
+    bowling_scorecard.each do |row|
+      player = Cricketer.find_by(name: row[0])
+
+      raise ActiveRecord::RecordNotFound, row[0] if player.nil?
+
+      player.innings_bowled += 1
+      player.balls_bowled += row[1]
+      player.runs_given += row[3]
+      player.wickets_taken += row[4]
+
+      player.save
+    end
   end
 
   # Delete the record associated with a player.
   #
   # Note: If you cannot find a player with given name, raise an
   # `ActiveRecord::RecordNotFound` exception.
   def self.ban(name)
-    raise NotImplementedError
+    player = Cricketer.find_by(name: name)
+
+    raise ActiveRecord::RecordNotFound, name if player.nil?
+
+    player.destroy
   end
 end

session_2/student_registry/app/models/student.rb

@@ -0,0 +1,6 @@
+class Student < ApplicationRecord
+  validates :cgpa, numericality: {
+    greater_than_equal_to: 0.0,
+    less_than_equal_to: 10.0
+  }
+end

session_2/student_registry/db/migrate/20210123124824_create_students.rb

@@ -0,0 +1,14 @@
+class CreateStudents < ActiveRecord::Migration[6.1]
+  def change
+    create_table :students do |t|
+      t.string :name
+      t.string :roll_number
+      t.string :branch
+      t.decimal :cgpa, precision: 4, scale: 2
+      t.text :address
+      t.integer :admission_year
+
+      t.timestamps
+    end
+  end
+end