fga-gpp-mds/2017.1-Escola-X

class Subject < ApplicationRecord
    belongs_to :teacher
    has_many :grades, dependent: :destroy
    has_many :classroom_subjects, dependent: :destroy
    has_many :alumns, through: :grades
    has_many :classrooms, through: :classroom_subjects
    belongs_to :classroom_grade
    validates_associated :grades
    validates_associated :alumns

  validates :name_subject,
              presence: { message: "Não pode estar em branco!" },
              length: { minimum: 5,
                    maximum: 20,
                    :too_short => "deve possuir mais de 5 caracteres.",
                    :too_long => "deve possuir no máximo 20 caracteres."}


  validates :teacher,
            presence: { message: "não válido para criar matéria!" },
            uniqueness: true

end