프로필 페이지에 닉네임, 자기소개 편집 기능 추가

routes.rb

  resources :users, only: [:show, :new, :edit, :create, :destroy, :update]

users_contoroller

  def update
    @user = User.find(params[:id])
    if @user.update(user_params)
      flash[:notice] = "変更しました。"
      redirect_to "/users/#{@user.id}/edit"
    else 
      flash[:alert] = "失敗しました"
      redirect_to "/users/#{@user.id}/edit"
    end
  end

  private
  def user_params
    params.require(:user).permit(:nickname,:introduce)
  end

edit.html.haml

.wrapper1.clearfix
  = render 'mypage/mypage-sidemenu'
  .profile-container
    %h2.container__profile プロフィール
    = form_for @user, url:"/users/#{@user.id}" , method: :patch, html:{class: "edit_form"} do |f|
      .container__name
        = image_tag "https://static.mercdn.net/images/member_photo_noimage_thumb.png", class: "image-tag"
        = f.text_field :nickname, value: "#{@user.nickname}" ,class: "edit_name"
      .container__text
        = f.text_area :introduce, value: "#{@user.introduce}",class: "introduce", placeholder: "例）こんにちは☆ ご覧いただきありがとうございます！かわいいものやきれいめオフィスカジュアル中心に出品しています。服のサイズは主に9号です。気持ちよくお取引できるよう心がけていますので、商品や発送方法などご質問がありましたらお気軽にどうぞ♪"
        .container__bottun
          = f.submit "変更する", class: 'change-profile-form__action-btn'

form_with면 왜 틀린지 몰라 formfor를 만들다.
위에서 말한 바와 같이 업데이트할 수 없습니다.
controller binding.pry, @user를 끼고 있습니다.valid?→@user.errors.full_메시지를 만든 후 비밀번호가 필요합니다.(콘솔에서 current user가 로그인 상태로 확인됨)

다른 페이지 (사용자 새 로그인) 의validation이 작용했습니다.

user.rb

  # バリデーション
  VALID_EMAIL_REGEX =                 /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i
  VALID_PHONE_REGEX =                 /\A\d{10}$|^\d{11}\z/
  VALID_ADDRESS_NUMBER_REGEX =        /\A[0-9]{3}-[0-9]{4}\z/
  validates :nickname,                presence: true, length: {maximum: 20}
  validates :email,                   presence: true, uniqueness: true, format: { with: VALID_EMAIL_REGEX }
  validates :password,                presence: true, length: {minimum: 6, maximum: 128},on: :save_to_session_before_phone
  validates :password_confirmation,   presence: true, length: {minimum: 6, maximum: 128},on: :save_to_session_before_phone
  validates :password,                length: {minimum: 6, maximum: 128},on: :update,allow_blank: true
  validates :password_confirmation,   length: {minimum: 6, maximum: 128},on: :update,allow_blank: true
  validates :last_name,               presence: true
  validates :first_name,              presence: true
  validates :last_name_kana,          presence: true
  validates :first_name_kana,         presence: true
  validates :birthdate_year,          numericality: true
  validates :birthdate_month,         numericality: true
  validates :birthdate_day,           numericality: true
  validates :phone_number,            presence: true, uniqueness: true, format: { with: VALID_PHONE_REGEX }
  validates :address_last_name,       presence: true
  validates :address_first_name,      presence: true
  validates :address_last_name_kana,  presence: true
  validates :address_first_name_kana, presence: true
  validates :address_number,          presence: true, format: { with: VALID_ADDRESS_NUMBER_REGEX }
  validates :address_prefecture,      presence: true
  validates :address_name,            presence: true
  validates :address_block,           presence: true
  validates :address_phone_number,    allow_blank: true, format: { with: VALID_PHONE_REGEX }
end

다음 변경 사항.
user.rb

validates :password,                presence: true, length: {minimum: 6, maximum: 128},on: :save_to_session_before_phone
  validates :password_confirmation,   presence: true, length: {minimum: 6, maximum: 128},on: :save_to_session_before_phone
  validates :password,                length: {minimum: 6, maximum: 128},on: :update,allow_blank: true
  validates :password_confirmation,   length: {minimum: 6, maximum: 128},on: :update,allow_blank: true

validation 추가, on: 동작 이름에서 이validation을 사용하는 장면을 지정합니다.
페이지에서 allow 편집blank이기 때문에 공백(미입력)에서 먼저 편집을 진행하면 편집할 수 있습니다.