为什么在password_reset的编辑操作中使用hidden_​​field_tag而不是f.hidden_​​field

Question

I'm doing chap12: Password Reset in rails railstutorial.org and i saw this code app/views/password_resets/edit.html.erb

<h1>Reset password</h1>

<div class="row">
  <div class="col-md-6 col-md-offset-3">
    <%= form_for(@user, url: password_reset_path(params[:id])) do |f| %>
      <%= render 'shared/error_messages' %>

      <%= hidden_field_tag :email, @user.email %>

      <%= f.label :password %>
      <%= f.password_field :password, class: 'form-control' %>

      <%= f.label :password_confirmation, "Confirmation" %>
      <%= f.password_field :password_confirmation, class: 'form-control' %>

      <%= f.submit "Update password", class: "btn btn-primary" %>
    <% end %>
  </div>
</div>

And PasswordResetsController class PasswordResetsController < ApplicationController

  def edit
    @user = User.find_by email: params[:email]
  end

  def update
    @user = User.find_by email: params[:email]
    if params[:user][:password].empty?
      add_errors
    elsif @user.update_attributes user_params
      log_in @user
      flash[:success] = t "controllers.password_reset.success"
      redirect_to @user
    else
      render :edit
    end
  end

end

Reset link like this: http://localhost:3000/password_resets/DCxf-6H4fyBf32QrW-d2Zg/edit?email=trag08%40gmail.com When click link, route call action edit and get email to params[:email] and view edit.html.erb and put email into hiddren field. And why in this code, they don't use f.hidden_field :email, @user.email .

I try use f.hidden_field :email, @user.email and edit update action in controller like this.

def update
        @user = User.find_by email: params[:user][:email]
        if params[:user][:password].empty?

Rails rase error: undefined method merge' for "xxx@gmail.com":String`, and it's not get user. Why like this? .

Answer 1

As you see in the tutorials example <%= hidden_field_tag :email, @user.email %> is not creating a param that's available in params[:user] .

It's creating a param that's available in params[:email]

When they call the email they use:

@user = User.find_by email: params[:email]

You use:

@user = User.find_by email: params[:user][:email]

---

I would recommend looking into what exactly is created by a rails helper tag as the one you're using. See Form Tag Helpers .