model_from_schema:gen

model_from_schema.rake

module ModelGenerator
  MODELS = {}
  module Evaluator
    module_function

    def create_table(table_name, *)
      MODELS[table_name.classify] = {
        has_many: [],
        belongs_to: [],
        has_many_foreign_key: [],
        belongs_to_foreign_key: []
      }
    end

    # 無視
    def add_index(*)
    end

    def add_foreign_key(from, to, column: nil, name: nil)
      fromc, toc = from.classify, to.classify
      if column
        MODELS[fromc][:belongs_to_foreign_key].push [to.singularize, column]
        MODELS[toc][:has_many_foreign_key].push [from.singularize, column]
      else
        MODELS[fromc][:belongs_to].push to.singularize
        MODELS[toc][:has_many].push from
      end
    end
  end

  def self.save
    MODELS.each do |klass, data|
      code = [
        "# #{klass}",
        "class #{klass} < ApplicationRecord",
        data[:has_many].map { |x| "  has_many :#{x}" },
        data[:belongs_to].map { |x| "  belongs_to :#{x}" },
        "end\n"
      ].flatten.join("\n")
      path = Rails.root.join("app", "models", "#{klass.underscore}.rb")

      unless File.exist?(path)
        File.write(path, code)
        puts "It generate the #{path}"
      end
    end
  end
end

namespace :model_from_schema do
  desc "Generate model files from db schema"

  task gen: :environment do
    s = ActiveRecord::Schema[7.0]
    def s.define(*, &block)
      ModelGenerator::Evaluator.class_eval(&block)
    end

    load Rails.root.join("db", "schema.rb")

    ModelGenerator.save
  end
end