showing off some of the basics of neo4j.rb 3

neo4jrb-demo.rb

[Student, Lesson, Teacher, Exam].each{|c| c.destroy_all }

ss101 = Lesson.create(subject: 'Social Studies', level: 101) 
ss102 = Lesson.create(subject: 'Social Studies', level: 102) 
math101 = Lesson.create(subject: 'Math', level: 101) 
math201 = Lesson.create(subject: 'Math', level: 201) 
geo103 = Lesson.create(subject: 'Geography', level: 103) 

sandra = Student.create(name: 'Sandra', age: 16) 
danny = Student.create(name: 'Danny', age: 15) 
bobby = Student.create(name: 'Bobby', age: 16) 
brian = Student.create(name: 'Brian', age: 25)

othmar = Teacher.create(name: 'Ms. Othmar')
samuels = Teacher.create(name: 'Harold Samuels')

ss101_midterm = Exam.create(name: 'SS 101 Midterm')
ss101_midterm.lesson = ss101
ss102_midterm = Exam.create(name: 'SS 102 Midterm')
ss102_midterm.lesson = ss102
math101_midterm = Exam.create(name: 'Math 101 Midterm')
math101_midterm.lesson = math101
math201_midterm = Exam.create(name: 'Math 201 Midterm')
math201_midterm.lesson = math201
geo103_midterm = Exam.create(name: 'Geo 103 Midterm')
geo103_midterm.lesson = geo103

[sandra, danny].each {|s| StudentLesson.create(from_node: s, to_node: ss101) }
[bobby, brian].each {|s| StudentLesson.create(from_node: s, to_node: ss102) }
[danny, bobby].each {|s| StudentLesson.create(from_node: s, to_node: math101) }
[sandra, brian].each {|s| StudentLesson.create(from_node: s, to_node: math201) }
[sandra, danny, bobby, brian].each {|s| StudentLesson.create(from_node: s, to_node: geo103) }

[ss101, ss102, geo103].each {|l| l.teachers << othmar }
[math101, math201].each {|l| l.teachers << samuels }

#sandra's lessons
sandra.lessons.each{|l| pp l.full_name }

#sandra's classmates
sandra.lessons.students.each_with_rel{|student, rel| pp "#{student.name} is in #{rel.from_node.full_name}" }

#sandra's classmates, age < 16
sandra.lessons.students(:s).where('s.age < {age}').params(age: 16).each_with_rel{|student, rel| pp "#{student.name} is in #{rel.from_node.full_name}" }

@grade = 35.upto(100).to_a
def take_exam(exam, student)
  ExamStudent.create(from_node: exam, to_node: student, grade: @grade.sample)
end

[sandra, danny].each{|s| take_exam(ss101_midterm, s) }
[bobby, brian].each{|s| take_exam(ss102_midterm, s) }
[danny, bobby].each{|s| take_exam(math101_midterm, s)}
[sandra, brian].each{|s| take_exam(math201_midterm, s)}
[sandra, danny, bobby, brian].each{|s| take_exam(geo103_midterm, s) }

pp sandra.gpa
pp bobby.gpa
pp brian.gpa

#sandra's lessons where she had a midterm grade greater than 69
sandra.exams(:e, :exam_rel).where('exam_rel.grade > {grade}').lesson(:l).params(grade: 70).pluck(:l, :exam_rel).each{|l, exam_rel| pp "#{l.full_name} with grade #{exam_rel.grade}"}
#all students who received grades better than 70 on an exam, returning the students, the exam and its rel, and the lesson
Student.as(:s).exams(:e, :exam_rel).where('exam_rel.grade > {grade}').lesson(:l).params(grade: 70).pluck(:s, :e, :exam_rel, :l).each do |student, exam, exam_rel, lesson|
  pp "#{student.name} (#{student.neo_id}) received a grade of #{exam_rel.grade} on #{exam.name} in lesson #{lesson.full_name}. Current GPA is #{student.gpa}."
end
# MATCH (s:`Student`), (e:`Exam`), s<-[exam_rel:`taken_by` {_classname: "ExamStudent"}]-(e:`Exam`), (l:`Lesson`), e-[rel2:`given_in`]->(l:`Lesson`) WHERE exam_rel.grade > {grade} RETURN s, e, exam_rel, l | {:grade=>70}