Admin csv import

Gemfile

@@ -42,6 +42,8 @@ gem "thruster", require: false
 gem "image_processing", "~> 2.2"
 gem "ruby-vips", "~> 2.0"
 
+gem "csv"
+
 group :development, :test do
   # See https://guides.rubyonrails.org/debugging_rails_applications.html#debugging-with-the-debug-gem
   gem "debug", platforms: %i[ mri windows ], require: "debug/prelude"

Gemfile.lock

@@ -115,6 +115,7 @@ GEM
     cruise (0.3.0-x86_64-darwin)
     cruise (0.3.0-x86_64-linux-gnu)
     cruise (0.3.0-x86_64-linux-musl)
+    csv (3.3.6)
     date (3.5.1)
     debug (1.11.1)
       irb (~> 1.10)
@@ -436,6 +437,7 @@ DEPENDENCIES
   brakeman
   bundler-audit
   capybara
+  csv
   debug
   faker (~> 3.8)
   herb
@@ -499,6 +501,7 @@ CHECKSUMS
   cruise (0.3.0-x86_64-darwin) sha256=5dcf048c20cfcaf208cdcdd6ddfd4410acb431ff18a84bd7441bba0c8b8d6b83
   cruise (0.3.0-x86_64-linux-gnu) sha256=a7bdd7c72307a450a9d37f3c7a90c118230ea6122663b32b8c8e52cad32adfa8
   cruise (0.3.0-x86_64-linux-musl) sha256=54ed6809f1d476bf99a3043bc256cca0efed8bbc9df93a55f4e49eac2bbcb7f4
+  csv (3.3.6) sha256=aba61e7e507a66f03d45cb1f3c4b6359861c3504038b422962875dce099e4456
   date (3.5.1) sha256=750d06384d7b9c15d562c76291407d89e368dda4d4fff957eb94962d325a0dc0
   debug (1.11.1) sha256=2e0b0ac6119f2207a6f8ac7d4a73ca8eb4e440f64da0a3136c30343146e952b6
   dotenv (3.2.0) sha256=e375b83121ea7ca4ce20f214740076129ab8514cd81378161f11c03853fe619d

app/controllers/admin/csv_controller.rb

@@ -0,0 +1,68 @@
+require "csv"
+
+class Admin::CsvController < AdminController
+  class CSVHeadersError < StandardError; end
+  class StudentBulkImportError < StandardError; end
+  class ClassroomBulkImportError < StandardError; end
+
+  IMPORT_ERRORS = [
+    CSVHeadersError,
+    StudentBulkImportError,
+    ClassroomBulkImportError,
+    CSV::MalformedCSVError,
+    StudentCsvImporter::InvalidClassroomError,
+    StudentCsvImporter::InvalidProgramError,
+    StudentCsvImporter::InvalidStudentError,
+    StudentCsvImporter::InvalidTeacherError
+  ].freeze
+
+  CSV_HEADERS = [ "Student First Name", "Student Last Name", "Grade Level", "Class Name", "Teacher", "Teacher Email",
+                 "Program", "Program Level" ].freeze
+
+  before_action :set_school
+
+  def download
+    csv_data = CSV.generate do |csv|
+      csv << CSV_HEADERS
+    end
+
+    send_data csv_data,
+              filename: "students-#{Date.today}.csv",
+              type: "text/csv; charset=utf-8",
+              disposition: "attachment"
+  end
+
+  def import
+    csv_file = params[:file]
+    return redirect_to school_students_path(@school), alert: "Choose a CSV file to import." if csv_file.blank?
+
+    csv = CSV.read(csv_file.path, headers: true)
+    validate_rows!(csv)
+    StudentCsvImporter.new(csv: csv, school_id: @school.id).import
+
+    redirect_to school_students_path(@school), notice: "Students were successfully imported."
+  rescue *IMPORT_ERRORS => error
+    redirect_to school_students_path(@school), alert: error.message
+  end
+
+  private
+    def set_school
+      @school = School.find(params.expect(:school_id))
+    end
+
+    def validate_rows!(csv)
+      raise CSVHeadersError, "Headers must match CSV headers" unless CSV_HEADERS == csv.headers
+
+      csv.each do |row|
+        raise CSVHeadersError, "Row must have same number of columns as headers" unless CSV_HEADERS.length == row.length
+
+        if @school.students.exists?(first_name: row["Student First Name"], last_name: row["Student Last Name"])
+          raise StudentBulkImportError, "Student: #{row["Student First Name"]} #{row["Student Last Name"]} already exists"
+        end
+
+        if @school.classrooms.exists?(name: row["Class Name"])
+          raise ClassroomBulkImportError, "Classroom: #{row["Class Name"]} already exists"
+        end
+      end
+    end
+end

app/services/student_csv_importer.rb

@@ -0,0 +1,124 @@
+
+
+class StudentCsvImporter
+  class InvalidClassroomError < StandardError; end
+  class InvalidProgramError < StandardError; end
+  class InvalidStudentError < StandardError; end
+  class InvalidTeacherError < StandardError; end
+
+  def initialize(csv:, school_id:)
+    @csv = csv
+    @school_id = school_id
+    @error_messages = {
+      classrooms: {},
+      teachers: {},
+      students: {}
+    }
+    @classrooms = {}
+    @teachers = {}
+    @students = []
+    @row_indexes = {}
+  end
+
+
+  def import
+    @csv.each_with_index do |row, index|
+      next if row.blank?
+
+      teacher = find_or_build_teacher(row)
+      classroom = find_or_build_classroom(row, teacher)
+
+      student = Student.new(
+        first_name: row["Student First Name"],
+        last_name: row["Student Last Name"],
+        grade_level: row["Grade Level"],
+        school_id: @school_id,
+        classroom: classroom
+      )
+
+      collect_errors(:teachers, teacher, index)
+      collect_errors(:classrooms, classroom, index)
+      collect_errors(:students, student, index)
+
+      @students << student
+    end
+
+    save_records
+  end
+
+
+
+private
+
+  def save_records
+    ActiveRecord::Base.transaction do
+      raise_validation_errors!
+
+      save_all(@teachers.values, InvalidTeacherError)
+      save_all(@classrooms.values, InvalidClassroomError)
+      save_all(@students, InvalidStudentError)
+
+      create_program_associations
+    end
+  end
+
+  # A uniqueness collision between two rows of the same file survives `valid?`,
+  # because neither record is persisted yet. Re-raise it in the shape the
+  # validation errors already use so callers only have to handle one thing.
+  def save_all(records, error_class)
+    records.each do |record|
+      record.save!
+    rescue ActiveRecord::RecordInvalid => error
+      raise error_class, { @row_indexes[record.object_id] => error.record.errors.full_messages }.to_s
+    end
+  end
+
+  def create_program_associations
+    @csv.each do |row|
+      teacher = @teachers[row["Teacher"]]
+      classroom = @classrooms[[ teacher.name, row["Class Name"] ]]
+
+      program = find_existing_program!(row["Program"])
+
+      classroom.classroom_programs.create_or_find_by!(program: program, level: row["Program Level"])
+    end
+  end
+
+  def find_existing_program!(name)
+    Program.find_by!(name: name)
+  rescue ActiveRecord::RecordNotFound
+    raise InvalidProgramError, "Program: #{name} does not exist"
+  end
+
+  def collect_errors(type, record, index)
+    @row_indexes[record.object_id] ||= index
+
+    return if record.valid?
+
+    @error_messages[type][index] = record.errors.full_messages
+  end
+
+  def raise_validation_errors!
+    raise InvalidClassroomError, @error_messages[:classrooms].to_s if @error_messages[:classrooms].any?
+    raise InvalidStudentError, @error_messages[:students].to_s if @error_messages[:students].any?
+    raise InvalidTeacherError, @error_messages[:teachers].to_s if @error_messages[:teachers].any?
+  end
+
+  def find_or_build_teacher(row)
+    @teachers[row["Teacher"]] ||= Teacher.new(
+      name: row["Teacher"],
+      email: row["Teacher Email"],
+      school_id: @school_id
+    )
+  end
+
+  def find_or_build_classroom(row, teacher)
+    key = [ teacher.name, row["Class Name"] ]
+
+    @classrooms[key] ||= Classroom.new(
+      school_id: @school_id,
+      name: row["Class Name"],
+      teacher: teacher
+    )
+  end
+end

config/routes.rb

@@ -25,6 +25,8 @@
         member { get :schedule }
       end
       resources :teachers, shallow: true, except: [ :show ]
+      get :csv_template, to: "admin/csv#download"
+      post :csv_import, to: "admin/csv#import"
     end
     resources :content_modules, except: [ :show ] do
       resources :links, shallow: true, except: %i[index show]