关于update_attributes!，如果参数没有更改，对应model层的validation没有被触发

[transcosmos]

centroller层执行保存和一时保存的代码：

@shain_tmp = ShainTmp.find_by_id(params[:id])
......
#一时保存的时候，设置为0；保存时，设置为1
Thread.current[:save_status_flg] = 0
@shain_tmp.update_attributes!(params[:shain_tmp])

model层关系：

class ShainTmp < ActiveRecord::Base
......
  has_many :gakureki_tmps, :dependent => :destroy, :order => "day_to"
  accepts_nested_attributes_for :gakureki_tmps,
                                :allow_destroy => true,
                                :reject_if => :all_blank
  attr_accessible :gakureki_tmps_attributes
......
end

class GakurekiTmp < ActiveRecord::Base
  belongs_to :shain_tmp
  attr_accessible :created_by, :day_from, :day_to, :del_flg, :dept, :dept_en, :end_cd, :lock_version, :memo, :school, :school_en, :seq_no, :start_cd, :subject, :subject_en, :updated_by

  #非空判断
  validates :end_cd, data_presence: { null_val: "20", tabname: @tabname },if: Proc.new { Thread.current[:save_status_flg] != 0 }
......
end

params[:shain_tmp]内容：

{"sei"=>"XX", "mei"=>"XX","job_cd"=>"",
"gakureki_tmps_attributes"=>{"0"=>{"id"=>"2593", "start_cd"=>"", "day_from"=>"",
 "end_cd"=>"", "day_to"=>"", "school"=>"", "school_en"=>"", "dept"=>"", "dept_en
"=>"", "subject"=>"", "subject_en"=>"", "memo"=>"", "_destroy"=>"false"}},......}

对于gakureki_tmps表的end_cd字段，当 Thread.current[:save_status_flg] 的值是0以外的值，会进行非空判断。

现在有这么个情况，我首先在页面上点了一时保存button， Thread.current[:save_status_flg] 的值是 0， 所以gakureki_tmps表的end_cd字段不进行非空判断，对于param传过来的参数顺利保存了，然后我在页面上又点了保存button，params参数没有做任何修改，此时Thread.current[:save_status_flg] 的值是 1，正常来说gakureki_tmps表的end_cd字段会进行validation判断。但是因为params没有改变，所以执行@shain_tmp.update_attributes!(params[:shain_tmp])的时候，gakureki_tmps表的记录被忽略了