Ruby on Rails：使用两个数据库记录字段填充下拉列表

Question

In my database I have a Users table that looks something like:

 User_ID    Firstname    Surname    Company
 1          Steve        Jobs       Apple
 2          Bill         Gates      Microsoft

What I am trying to do is make a drop down menu in a form that would allow a user to choose from selecting their name or their company, eg when Steve Jobs is logged in he can either select "Steve" or "Apple" in the drop down menu.

What I have tried so far is the following:

<%= f.select :from_name, [session[:user_id],session[:user_id]] %>

Which obviously didn't work because it only returns the user id of the logged in user.

<%= f.select :from_name, [@user.firstname,@user.company] %>

Which gave me the error undefined method firstname for nil:NilClass`

My Users controller is as follows:

class UsersController < ApplicationController
before_filter :check_authorization, :except => [:show, :new, :create, :search ]

  def index
    @users = User.all
  end

  def show
    @user = User.find(params[:id])
  end

  def new
    @user = User.new
  end

  def edit
    @user = User.find(params[:id])
  end

  def create
    @user = User.new(user_params)
    @user.role = "customer"
    if @user.save       
        session[:user_id] = @user.id
        # Save a copy of the email address entered by the user into the Accounts table
        @account = Account.create(email: params[:user][:primaryemailaddress], user_id: session[:user_id])
        redirect_to root_path
    else
        render 'new'
    end
  end

  def update
    @user = User.find(params[:id])

    if @user.update(user_params)
        redirect_to @user
    else
        render 'edit'
    end
  end

  def destroy
    @user = User.find(params[:id])
    @user.destroy
    redirect_to users_path
  end

  private

  def user_params
    params.require(:user).permit(:title, :firstname, :surname, :housenumber, :street, :city, :postcode, :company, :primaryemailaddress, :password)
  end  
end

And my _form.html.erb is:

<%= form_for(@email) do |f| %>
  <% if @email.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@email.errors.count, "error") %> prohibited this email from being saved:</h2>

      <ul>
      <% @email.errors.full_messages.each do |message| %>
        <li><%= message %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <p>
    <%= f.label :from_name %><br>
    <%= f.select :from_name, [current_user.firstname, current_user.company] %>
  </p>

  <p>
    <%= f.label :From_Email_Address %><br>
    <%= f.collection_select :account_id, Account.where(user_id: session[:user_id]), 
      :id,:email %>
  </p>

  <p>
    <%= f.label :to %><br>
    <%= f.text_field :to %>
  </p>

  <p>
    <%= f.label :cc %><br>
    <%= f.text_field :cc %>
  </p>

  <p>
    <%= f.label :bcc %><br>
    <%= f.text_field :bcc %>
  </p>

  <p>
    <%= f.label :subject %><br>
    <%= f.text_field :subject %>
  </p>

  <p>
    <%= f.label :message %><br>
    <%= f.text_field :message %>
  </p>

  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

I'm not too sure how to solve this issue, can someone please help.

Answer 1

@BenSmith I guess you are accessing EmailsController . And on that controller's new or edit method there is no @user variable.

In your edit and new method add

@user = User.find(session[:user_id])

Answer 2

undefined method firstname for nil:NilClass

Seems like some how @user is nil

create a helper and check for presence of @user

<%= f.select :from_name, dropdown_values %>

application_helper.rb

def dropdown_values
  if @user.present?
    [@user.firstname, @user.company]
  else
    ['default', 'values']
  end
end

Answer 3

<p>
    <%= f.label :from_name %><br>
    <%= f.select :from_name, [current_user.firstname, current_user.company] if @user.present?%>
  </p>

because User.new time create blank object doesn't find username.i hope its will be help you.