Learning Rails Book Forum

Activerecord Find

Sun, 18 Oct 2009 08:45:25 -0400

Learning Rails: I have used this book to build my working model (very helpful).
I have had a problem for awhile trying to find/match a referral remail address (unique) with a profile pemail address(unique). Then rendering the profile page based on the find. I'm using the default parms.id method. Also created an index on pemail in the profile data base. Just can’t get it to work.
Can anyone recomment my next book that can explain a srting search/find (soup to nuts)?
Class Profile < ActiveRecord::Base
has_many :referrals, :dependent => :destroy
Class Referral < ActiveRecord::Base
has_and_belongs_to_many :profile

Helpers, Form Builders, Names

Sun, 06 Sep 2009 17:53:22 -0400

I'm plowing through Chapter 8 trying to define my own helper methods, and I'm getting some questions:
- what is the difference between a helper and a form builder? I see there's a people_helper.rb which contains a module PeopleHelper with nothing in it.
The book around pg 134 starts adding stuff to form builder files. After playing around trying to define my own methods, I find that there seems to be a naming rule:
- the :builder references a name like AxxxBxxx for the form builder
- the file name has to be in the form axxx_bxxx.rb
- the class name has to be in the form AxxxBxxx

So, on pg 135 where it says that Rails will know to look for /app/helpers/TidyFormBuilder, this actually means that it looks for class TidyFormBuilder in the file
/app/helpers/tidy_form_builder.rb

Is that correct?

T.

Chapter 9 Developing Model Relationships

Fri, 21 Aug 2009 04:21:45 -0400

Hi Guys,

I am hoping someone is able to help me, I have been following this book through and I have only now ran into something i can solve myself from the errata,

I am getting a NoMethodError when i try to add a new course for student, or view the coruses.html.erb file, I have been over all the coding in courses, courses.controller, students.controller etc and i can't figure out the issue and its driving me nuts, does anyone have a clue?

NoMethodError in Students#courses

Showing app/views/students/courses.html.erb where line #1 raised:

You have a nil object when you didn't expect it!
The error occurred while evaluating nil.name

Extracted source (around line #1):

1:

<%= @student.name %>'s Courses

2:
3: <% if @courses.length > 0 %>
4: <% form_tag(course_remove_student_path(@student)) do %>

CODE

<%= @student.name %>'s Courses

<% if @courses.length > 0 %>
  <% form_tag(course_remove_student_path(@student)) do %>

<% for course in @courses do %>

<% end %>
              Course        Remove?      
    <%=h course.name %>    <%= check_box_tag "course[]", course.id %>  

<%= submit_tag "Remove checked courses" %>
<% end %>
<% else %>
Not enrolled in any courses yet.

<% end %>

 Enroll in new course

<% if @student.courses.count < Course.count then %>
  <% form_tag(course_add_student_path(@student)) do %>
    <%= select_tag(:course, options_from_collection_for_select(@student.unenrolled_courses, :id, :anem)) %>
    <%= submit_tag 'Enroll' %>
    <% end %>
    <% else %>
<%=h @student.name %> is enrolled in every course. 

    <% end %>

<%= link_to "back", @students %>

Course	Remove?
<%=h course.name %>	<%= check_box_tag "course[]", course.id %>

CODE

CODE
class Course < ActiveRecord::Base
  has_and_belongs_to_many :students
  
  def enrolled_in?(course)
    self.courses.include?(course)
  end
  
  def unenrolled_courses
    Course.find(:all) - self.courses
  end
  
end

CODE

class Student < ActiveRecord::Base
  has_many :awards, :dependent => :destroy
  has_and_belongs_to_many :courses
  
  def name
    given_name + " " + family_name
  end
end

CODE

class CoursesController < ApplicationController
  # GET /courses
  # GET /courses.xml
  def index
    @courses = Course.all

    respond_to do |format|
      format.html # index.html.erb
      format.xml  { render :xml => @courses }
    end
  end

  # GET /courses/1
  # GET /courses/1.xml
  def show
    @course = Course.find(params[:id])

    respond_to do |format|
      format.html # show.html.erb
      format.xml  { render :xml => @course }
    end
  end

  # GET /courses/new
  # GET /courses/new.xml
  def new
    @course = Course.new

    respond_to do |format|
      format.html # new.html.erb
      format.xml  { render :xml => @course }
    end
  end

  # GET /courses/1/edit
  def edit
    @course = Course.find(params[:id])
  end

  # POST /courses
  # POST /courses.xml
  def create
    @course = Course.new(params[:course])

    respond_to do |format|
      if @course.save
        flash[:notice] = 'Course was successfully created.'
        format.html { redirect_to(@course) }
        format.xml  { render :xml => @course, :status => :created, :location => @course }
      else
        format.html { render :action => "new" }
        format.xml  { render :xml => @course.errors, :status => :unprocessable_entity }
      end
    end
  end

  # PUT /courses/1
  # PUT /courses/1.xml
  def update
    @course = Course.find(params[:id])

    respond_to do |format|
      if @course.update_attributes(params[:course])
        flash[:notice] = 'Course was successfully updated.'
        format.html { redirect_to(@course) }
        format.xml  { head k }
      else
        format.html { render :action => "edit" }
        format.xml  { render :xml => @course.errors, :status => :unprocessable_entity }
      end
    end
  end

  # DELETE /courses/1
  # DELETE /courses/1.xml
  def destroy
    @course = Course.find(params[:id])
    @course.destroy

    respond_to do |format|
      format.html { redirect_to(courses_url) }
      format.xml  { head k }
    end
  end
  # GET /courses/1/roll
  def roll
    @course = Course.find(params[:id])
  end
  # GET /students/1/courses
  def courses
    @student = Student.find(params[:id])
    @course = @student.courses
  end
  # PSOT /students/1/course_add?course_id=2
  # (note no real query string, just convenient notation for parameters)
  
  def course_add
    #convert ids from routing to objects
    @student = Student.find(params[:id])
    @course = Course.find(params[:course])
    
    unless @student.enrolled_in?(@course)
      @student.courses << @course
      flash[:notice] = 'Course was successfully added'
    else
        flash[:error] = 'Student was already enrolled'
    end 
    redirect_to :action => :courses, :id => @student
  end
  
  def course_remove
    @student = Student.find(params[:id])
    course_ids = params[:courses]
    unless course_ids.blank?
      course_ids.each do |course_id|
        course = Course.find(course_id)
        if @student.enrolled_in?(course)  
          logger.info "Removing student from course #{course.id}"
          @student.courses.delete(course)
          flash[:notice] = 'Course was successfully deleted'
        end
      end
    redirect_to :action => :courses, :id => @student
end
end
end
  

CODE

class StudentsController < ApplicationController
  # GET /students
  # GET /students.xml
  def index
    @students = Student.all

    respond_to do |format|
      format.html # index.html.erb
      format.xml  { render :xml => @students }
    end
  end

  # GET /students/1
  # GET /students/1.xml
  def show
    @student = Student.find(params[:id])

    respond_to do |format|
      format.html # show.html.erb
      format.xml  { render :xml => @student }
    end
  end

  # GET /students/new
  # GET /students/new.xml
  def new
    @student = Student.new

    respond_to do |format|
      format.html # new.html.erb
      format.xml  { render :xml => @student }
    end
  end

  # GET /students/1/edit
  def edit
    @student = Student.find(params[:id])
  end

  # POST /students
  # POST /students.xml
  def create
    @student = Student.new(params[:student])

    respond_to do |format|
      if @student.save
        flash[:notice] = 'Student was successfully created.'
        format.html { redirect_to(@student) }
        format.xml  { render :xml => @student, :status => :created, :location => @student }
      else
        format.html { render :action => "new" }
        format.xml  { render :xml => @student.errors, :status => :unprocessable_entity }
      end
    end
  end

  # PUT /students/1
  # PUT /students/1.xml
  def update
    @student = Student.find(params[:id])

    respond_to do |format|
      if @student.update_attributes(params[:student])
        flash[:notice] = 'Student was successfully updated.'
        format.html { redirect_to(@student) }
        format.xml  { head k }
      else
        format.html { render :action => "edit" }
        format.xml  { render :xml => @student.errors, :status => :unprocessable_entity }
      end
    end
  end

  # DELETE /students/1
  # DELETE /students/1.xml
  def destroy
    @student = Student.find(params[:id])
    @student.destroy

    respond_to do |format|
      format.html { redirect_to(students_url) }
      format.xml  { head k }
    end
  end
end

Actioncontroller::routingerror

Mon, 27 Jul 2009 22:04:22 -0400

hi, so after I've upgraded from rails 2.1.0 to 2.3.3 I keep getting this error:

image_url failed to generate from {:controller=>"images", :action=>"show", :id=>"remove.gif"}, expected: {:controller=>"images", :action=>"show"}, diff: {:id=>"remove.gif"}
Extracted source (around line #202):

199:
200: // remove column
201: var removelinkhover = "click to remove,\n ⌘-click to remove all,\noption-click to remove all reserved hosts"
202: var remove_link = Builder.node( 'img', {src:"<%=image_path "remove.gif"%>",
203: title:removelinkhover,
204: style:"cursor:pointer"} )
205: remove_link.addEventListener('click', function( e ){ removeMachineFromReservationHandler( e, id ) } )

I've tried to fix it for quite a long time and ran out of ideas. Any help would be appreciated!

Chapter 8. Wrap_field Is Not Generating The Label Names.

Sun, 28 Jun 2009 17:17:45 -0400

I seem to be having issues at the end of chapter 8. I have doubled checked my code and all is good. Everything works except the labels just print label to the screen instead of their names name, email, etc.

Here's my wrapping_tidy_form_builder class

CODE

class WrappingTidyFormBuilder < ActionView::Helpers::FormBuilder

  def country_select(method, options={}, html_options={})
    select(method, [['Canada', 'Canada'],
                     ['Mexico', 'Mexico'],
                     ['United Kingdom', 'UK'],
                     ['United States of America', 'USA']],
                  options, html_options)
  end


  def text_field(method, options={})
    wrap_field(label_for(method, options) + super(method, options), options)
  end

  def text_area(method, options={})
    wrap_field(label_for(method, options) + super(method, options), options)
  end

  def password_field(method, options={})
    wrap_field(label_for(method, options) + super(method, options), options)
  end

  def file_field(method, options={})
    wrap_field(label_for(method, options) + super(method, options), options)
  end


  def date_select(method, options = {}, html_options = {})
   wrap_field(label_for(method, options) + super(method, options, html_options), options)
  end

  def datetime_select(method, options = {}, html_options = {})
   wrap_field(label_for(method, options) + super(method, options, html_options), options)
  end

  def select(method, choices, options = {}, html_options = {})
    wrap_field(label_for(method, options) + super(method, choices, options, html_options), options)
  end

  def check_box(method, options = {}, checked_value = "1", unchecked_value = "0")
    wrap_field(label_for(method, options) + super(method, options, checked_value, unchecked_value), options)
  end

  private
  def label_for(method, options={})
    extra = ""
    if options[:required]
      extra = " <span class='required_mark'>*</span>"
    end
    label(:label || method) + extra + "<br />"
  end

  def wrap_field(text, options={})
    field_class = "field"
    if options[:required]
      field_class = "field required"
    end
    "<div class='#{field_class}'>" + text + "</div>"
  end

end

And here is the form partial

CODE

<%= error_messages_for :person %>

<% form_for(:person, @person,
        :url => { :action => ( @person.new_record? ? "create" : "update" ) },
        :builder => WrappingTidyFormBuilder) do |f| %>



     <%= f.text_field :name, :required => true %>

    <%= f.password_field :secret, :required => true %>

    <%= f.country_select :country, :required => true %>

    <%= f.text_field :email, :required => true %>

    <%= f.text_area :description, :rows => 10, :cols => 30 %>

    <%= f.check_box :can_send_email , :required => true%>

    <%= f.text_field :graduation_year %>

    <%= f.text_field :body_temperature %>

    <%= f.text_field :price %>

    <%= f.date_select :birthday, :required => true %>

    <%= f.datetime_select :favorite_time, :required => true %>

    <%= f.file_field :photo %>

  <p>
    <%= f.submit "Update" %>
  </p>
<% end %>

Any help is appreciated. Thanks.
-Scott

Running Sample Code?

Fri, 12 Jun 2009 02:41:44 -0400

I admit it, I got lazy with the typing and let a few chapters slip by without actually keeping my local guestbook app caught up with the code samples. Now I'd like to run the code samples provided on this site, but I'm running into trouble.

The first problem was my rails version number, as defined in environment.rb. I updated:

"RAILS_GEM_VERSION = '2.0.2' unless defined? RAILS_GEM_VERSION"

to:

"RAILS_GEM_VERSION = '2.3.2' unless defined? RAILS_GEM_VERSION"

Next, I had to change "controllers/application.rb" to controllers/application_controller.rb"

Now I think I'm having trouble with migrations. I had a db table built from ~chapter 6 or so (now chapter 8), and I began by running "rake db:rollback" a few times. Then I ran "rake db:migrate" and tried to run the app. All's well and good, until I tried "new person." This throws an exception to the tune of:

"ActionController::RoutingError in People#new

Showing app/views/people/_form.html.erb where line #5 raised:

person_url failed to generate from {:controller=>"people", :action=>"show", :id=>#}, expected: {:controller=>"people", :action=>"show"}, diff: {:id=>#}"

What's my next move here? Or just yell at me for being lazy, that's cool too.

I <3 This Forum

Wed, 03 Jun 2009 18:03:49 -0400

I truly appreciate the work you're doing to maintain this forum. It's enhancing my experience with the book tremendously. Thank you Simon!

Chapter 8; File Upload Form; Name Error

Sun, 31 May 2009 02:23:21 -0400

I'm very new to Rails, so please bear with me.

I'm getting a name error when I try to look at my show view in my browser. I followed the book's instructions verbatim, I even included the change to the code on page 124 as noted in the errata. Any tips on what I may be doing wrong here?

Here's the error that I'm getting:

CODE

undefined local variable or method `extension' for #

Extracted source (around line #4): 

2:   
3:     
4: 	<% if @theater.has_photo? %>
5: 		<%= image_tag @theater.photo_path %>
6: 	<% else %>
7: 	No photo.

Note: "theater" is the name of the table that I'm inserting the extension column into; it takes the place of "person" in the book example.

Also, I'm running Rails on a Mac and editing with Xcode, if that helps.

Thanks very much!

Country_select And The LabelTue, 19 May 2009 11:25:00 -0400

The fourth paragraph on page 137 says "Remember how country_select calls the select method? It now calls the method that provides the label." To which method does that second sentence refer? Removing the "f.label" call from _form.html.erb results in no label on the country field.

Ch 4 Page 52 Example Code Problem - GuestThu, 14 May 2009 17:27:05 -0400

When I run the browser, I get an error "uninitialized constant EntriesController::Entry" from the example line @entries = Entry.find(:all). See page 52 example 4.7

Can't Run "hello"Mon, 11 May 2009 11:13:04 -0400

Hi,

I can't run the first hello program (chapter 2).

I generated the hello index successfully, but when I went to localhost:3000/hello  I get the following error: 

We're sorry, but something went wrong.

We've been notified about this issue and we'll take a look at it shortly.

I also tried all the previous steps (including a new install of ruby and rails) on another computer and got the same results.

Thanks for any help.

Rails 1 Or Rails 2Mon, 20 Apr 2009 12:59:36 -0400

Which version does this book cover? It doesn't mention anything in the description.

Doesn't (:label || Method) Always Return :label?Sat, 11 Apr 2009 23:23:42 -0400

On p. 136 we have:

"
(:label || method)

This looks for an option named :label, letting you specify label text for the field through a :label parameter. If there isn't a :label, the || will fall through to method, which will create a label with the default -- the internal name of the field."

Won't this expression always return the value ":label"?

Thanks in advance!

Ch. 7: :scope & Rails 2.3.2§Thu, 02 Apr 2009 09:46:46 -0400

Hiya, 

I'm really enjoying the book, but note that there appears to be an error with using :scope under Rails 2.3.2. Namely, it doesn't appear to check the named scope 

Label_for In Country_select Fails In 2.2.2Mon, 02 Mar 2009 11:02:36 -0500

The chapter 8 examples using a custom country_select helper to override the base work up until you try to add the label_for in an attempt to match country_select invocation to the other cleaned up calls.

Country_select is now a plugin, and not part of the rails core, so the "super" in label_for doesn't find a super class.