Ruby 未定义的方法 `strftime' for nil:NilClass

Question

I've only been working with Ruby for a short time and I've hit a wall today while working on a calendar to put requests on. I spent time searching through different undefinied method error documents on stackoverflow, the ruby guides, etc. as well as looking into strftime. I found a solution that partially solved my problem using try, but now it is not actually passing the strftime through to show on the request, even though the rails server is picking it up in the post. I can get to my calendar fine, and hit the new request button, fill out the form, but when I go to post that form the browsers gives me this:

undefined method `strftime' for nil:NilClass

Extracted source (around line #3):

1: <h1><%= @vacationrequest.request_name %></h1>
2: 
3: <p class="info">Requested For <%= @vacationrequest.request_date.strftime("%B %e, %Y") %></p>
4: 
5: <%= simple_format @vacationrequest.message %>
6: 

And I get this error on the Rails server:

Started GET "/vacationrequests/1" for 127.0.0.1 at 2012-10-17 15:18:14 -0400
Processing by VacationrequestsController#show as HTML
Parameters: {"id"=>"1"}
←[1m←[35mVacationrequest Load (0.0ms)←[0m SELECT "vacationrequests".* FROM "v
acationrequests" WHERE "vacationrequests"."id" = ? LIMIT 1 [["id", "1"]]
Rendered vacationrequests/show.html.erb within layouts/application (15.6ms)
Completed 500 Internal Server Error in 31ms

ActionView::Template::Error (undefined method strftime' for nil:NilClass):
1: <h1><%= @vacationrequest.request_date %></h1>
2:
3: <p class="info">Requested For <%= @vacationrequest.request_date.strftime(
"%B %e, %Y") %></p>
4:
5: <%= simple_format @vacationrequest.message %>
6:
app/views/vacationrequests/show.html.erb:3:inapp_views_vacationrequests_sho
w_html_erb_217743956_18446544'

This is my show view:

<h1><%= @vacationrequest.request_name %></h1>

<p class="info">Requested For <%= @vacationrequest.request_date.strftime("%B %e, %Y") %></p>

<%= simple_format @vacationrequest.message %>

<p>
  <%= link_to "Edit Request", edit_vacationrequest_path(@vacationrequest) %> |
  <%= link_to "Back to Requests", vacationrequests_path %>
</p>

and this is the _form that the user puts the request information into:

<%= form_for @vacationrequest do |f| %>
  <% if @vacationrequest.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@vacationrequest.errors.count, "error") %> prohibited this request from being saved: if this continue to happens please email the error to alex@allsafeindustries.com</h2>
      <ul>
      <% @vacationrequest.errors.full_messages.each do |msg| %>
        <li><%= msg %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= f.label :request_name %><br />
    <%= f.text_field :request_name %>
  </div>
  <div class="field">
    <%= f.label :request_date %><br />
    <%= f.text_field :request_date %>
  </div>
  <div class="field">
    <%= f.label :message %><br />
    <%= f.text_area :message %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

Finally here are my show and index methods in my controller:

  def index
    @vacationrequests = Vacationrequest.all
    @vacationrequests_by_date = @vacationrequests.group_by(&:request_date)
    @date = params[:date] ? Date.parse(params[:date]) : Date.today
  end

  def show
    @vacationrequest = Vacationrequest.find(params[:id])
  end

Can anybody direct me to what is out of place or why this is nil? Thank you.

In response to the answer here is what I am now getting from the server:

Started POST "/vacationrequests" for 127.0.0.1 at 2012-10-17 20:18:00 -0400
Processing by VacationrequestsController#create as HTML
  Parameters: {"utf8"=>"√", "authenticity_token"=>"E1+xXP0pAIQpwMZruswxIZIrTZB3b
c3NlW3iRv9OLqU=", "vacationrequest"=>{"request_name"=>"One more time", "request_
date"=>"10/31/2012", "message"=>"Lucky number 7?"}, "commit"=>"Create Vacationre
quest"}
  ←[1m←[35m (0.0ms)←[0m  begin transaction
  ←[1m←[36mSQL (15.6ms)←[0m  ←[1mINSERT INTO "vacationrequests" ("created_at", "
message", "request_date", "request_name", "updated_at") VALUES (?, ?, ?, ?, ?)←[
0m  [["created_at", Thu, 18 Oct 2012 00:18:00 UTC +00:00], ["message", "Lucky nu
mber 7?"], ["request_date", nil], ["request_name", "One more time"], ["updated_a
t", Thu, 18 Oct 2012 00:18:00 UTC +00:00]]
  ←[1m←[35m (109.2ms)←[0m  commit transaction
Redirected to http://localhost:3000/vacationrequests/7
Completed 302 Found in 125ms (ActiveRecord: 124.8ms)


Started GET "/vacationrequests/7" for 127.0.0.1 at 2012-10-17 20:18:01 -0400
Processing by VacationrequestsController#show as HTML
  Parameters: {"id"=>"7"}
  ←[1m←[36mVacationrequest Load (0.0ms)←[0m  ←[1mSELECT "vacationrequests".* FRO
M "vacationrequests" WHERE "vacationrequests"."id" = ? LIMIT 1←[0m  [["id", "7"]
]
  Rendered vacationrequests/show.html.erb within layouts/application (15.6ms)
    Completed 500 Internal Server Error in 16ms

ActionView::Template::Error (undefined method `strftime' for nil:NilClass):
    1: <h1><%= @vacationrequest.request_name %></h1>
    2: <%= debug @vacationrequest %>
    3: <p class="info">Requested For <%= @vacationrequest.request_date.strftime(
"%B %e, %Y") %></p>
    4:
    5: <%= simple_format @vacationrequest.message %>
    6:
  app/views/vacationrequests/show.html.erb:3:in `_app_views_vacationrequests_sho
w_html_erb___377763931_36688344'

I also used the view debug and checked my scheme and all of the attributes seemed to line up correctly.

As for the request in the comments here is my Vacationrequest model:

class Vacationrequest < ActiveRecord::Base
  attr_accessible :message, :request_name, :request_date
end

Once again I can't thank you enough for your help.

Here is the schema:

ActiveRecord::Schema.define(:version => 20121016194123) do

  create_table "vacationrequests", :force => true do |t|
    t.string   "request_name"
    t.date     "request_date"
    t.text     "message"
    t.datetime "created_at",   :null => false
    t.datetime "updated_at",   :null => false
  end
end

and the create controller action code:

def create
  @vacationrequest = Vacationrequest.new(params[:vacationrequest])
  if @vacationrequest.save
    redirect_to @vacationrequest, notice: "Created Request!"
  else
    render :new
  end
end

As I'm looking at this, is part of the problem my schema being plural and my controller being singular? Thanks again.

Answer 1

First you have to make sure if there is 'request_date' filled before you create a record by applying ActiveRecord validations.

Secondly, you can use ruby's try method to avoid such exceptions

<%= @vacationrequest.try(:request_date).try(:strftime, '%B %e, %Y') %>

Happy Coding !

Update

In the newer version of Ruby, you can use &. -> lonely operator instead of the solution above. It is also called safe navigation operator .

<%= @vacationrequest&.request_date&.strftime('%B %e, %Y') %>

Answer 2

@vacationrequest.request_date is nil, so the record you're looking at is missing the request date. It sounds like you have bad data. In this situation, I'd debug why by:

1. Dumping the @vacationrequest in the view -- <%= debug @vacationrequest %> (or from your controller: fail @vacationrequest.inspect ).
2. Checking in Rails console ( rails c ) -- what does Vactionrequest.find(some_id) yield?
3. Optionally, checking the DB entry.

However you're inputting vacation requests is not saving request dates, so there's probably a bug in your create controller action, model schema, or model validation.

Answer 3

Shioyama thank you so much for suggesting this:

validates :request_date, :presence => true

I'm really going to invest the time in learning about the debugging and validation Rails promotes. Because of this I figured out specifically that the datepicker in JQuery wasn't passing through correctly. I went into my assests > javascripts > vacationrequests.js.coffee and found I had left () on the end like this:

jQuery ->
  $('#vacationrequest_request_date').datepicker()
    dateFormat: 'yy-mm-dd'

Once I removed the brackets like this:

jQuery ->
  $('#vacationrequest_request_date').datepicker
    dateFormat: 'yy-mm-dd'

Everything is working, Index, Show, Edit, Update, New. Thank you both for all the suggestions and showing me how to run this down.