Rails - Apr 2009 - beginning ruby session problem / how do I rollback with git?

Hi,

Rails 2.3.2

I''m following along with the examples in AWDWR (3rd), and around about
p. 103, where you are working with a session table you created, I
decided to free lance a bit.  At some point, I tried to "clear" the
session by doing the following:

class StoreController < ApplicationController
...

private
  def find_cart
     #session[:cart] ||= Cart.new
     session[:cart] = Cart.new  #<------********
  end

I figured that would "erase" the old cart, and let me continue with a
new, empty cart.  However, everything is completely messed up now, and
when I try to access a "store page" (which lists the products for
sale)
using the following url:

http://localhost:3000/store

I get an error page that says:

  We''re sorry but something went wrong.
  We''ve been notified about this issue and
  we will take a look at it shortly.

As a fix, I tried rolling back the migration that created the session
table:

rake db:rollback

and then doing:

db:migrate

but I get that same error page.  So I''m stuck.  So much for free
lancing.  Is there some obvious way I can get rid of that error page and
get sessions working again.

Alternatively, I have git installed and I committed my changes at the
end of the last chapter(p. 96).  But I''ve read several git tutorials,
and I can''t figure out how to rollback to a previous version of my
code.

Thanks.
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7stud -- wrote:
> Hi,
> 
> Rails 2.3.2
> 
> However, everything is completely messed up now, and
> when I try to access a "store page" (which lists the products for
sale)
> using the following url:
> 
> http://localhost:3000/store
> 
> I get an error page that says:
> 
>   We''re sorry but something went wrong.
>   We''ve been notified about this issue and
>   we will take a look at it shortly.
> 
Sorry, I can access the store page.  It''s when I click a button that 
calls an add_to_cart action that I get that error message.  This is the 
url after I click on the add_to_cart button:

http://localhost:3000/store/add_to_cart/5
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7stud -- wrote:
>
> Sorry, I can access the store page.  It''s when I click a button
that
> calls an add_to_cart action that I get that error message.  This is the 
> url after I click on the add_to_cart button:
> 
> http://localhost:3000/store/add_to_cart/5
Here is the add_to_cart action:


class StoreController < ApplicationController
  def index
    @products = Product.find_products_for_sale

    now = Time.now
    @date = now.strftime("%m/%d/%Y")
    @time = now.strftime("%I:%M%p")
  end

  def add_to_cart
    product = Product.find(params[:id])
    @cart = find_cart
    @cart.add_product(product)

  end

private
  def find_cart
    session[:cart] ||= Cart.new
  end
end

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7stud -- wrote:
> private
>   def find_cart
>     session[:cart] ||= Cart.new
>   end

If I change that method to:

def find_cart
    Cart.new
end

then clicking on an "add to cart" button no longer shows me the error 
message.  I get a view that lists what was added to the cart.  However, 
without sessions the view just shows the current item that is being 
added.

As soon as I add back the line that mentions sessions:
> private
>   def find_cart
>     session[:cart] ||= Cart.new
>   end
I get the error message.

I tried rolling back the migration again:

rake db:rollback

then deleting the migration file:

/depot/db/migrate$ 20090423153751_create_sessions.rb

then recreating the migration file:

/depot$ rake db:sessions:create

and recreating the table:

/depot$ rake db:migrate

then restarting the server.  But that did not solve my problem.





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I figured out how to rollback with git from this website:

http://www-cs-students.stanford.edu/~blynn/gitmagic/ch02.html#_advanced_undo_redo

$ git log
commit 1964b4f78d82da730ccf5fc6d1ba7d1e1b5ae266
Author: me
Date:   Wed Apr 22 18:57:48 2009 -0600

    End of chapter 7, p. 96

commit a262fdcd503766cae2c5643923180480151ff669
Author: me
Date:   Tue Apr 21 03:28:49 2009 -0600

    Initial import
/depot$ git reset --hard 1964b4f78d82da730ccf5fc6d1ba7d1e1b5ae266
HEAD is now at 1964b4f End of chapter 7, p. 96
$

However, apparently doing a rollback doesn''t delete the new files you 
created since the last commit.  So, I also deleted the migration file 
for creating the sessions table.

Then I started over with the steps at the beginning of the chapter. 
After adding all the necessary code, I clicked on the add to cart 
button, and I get the same error message:

http://localhost:3000/store/add_to_cart/5

   We''re sorry, but something went wrong.
   We''ve been notified about this issue and we''ll take a look
at it
shortly.

So it seems like there is something wrong with my database.
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7stud -- wrote:
> So it seems like there is something wrong with my database.
I tried rolling back my migrations to the beginning:

/depot$ rake db:migrate VERSION=0
(in /Users/me/2testing/dir1/rails/depot)
==  CreateSessions: reverting 
================================================-- drop_table(:sessions)
   -> 0.0014s
==  CreateSessions: reverted (0.0016s) 
=======================================
==  AddTestData: reverting 
=====================================================  AddTestData: reverted
(0.0034s)
==========================================
==  AddPriceToProduct: reverting 
=============================================-- remove_column(:products, :price)
   -> 0.0263s
==  AddPriceToProduct: reverted (0.0265s) 
====================================
==  CreateProducts: reverting 
================================================-- drop_table(:products)
   -> 0.0010s
==  CreateProducts: reverted (0.0012s) 
=======================================
which left me with this:

/depot$ sqlite3 db/development.sqlite3

SQLite version 3.6.13
Enter ".help" for instructions
Enter SQL statements terminated with a ";"

sqlite> .mode line
sqlite> select * from sqlite_master;

    type = table
    name = schema_migrations
tbl_name = schema_migrations
rootpage = 2
     sql = CREATE TABLE "schema_migrations" ("version"
varchar(255) NOT
NULL)

    type = index
    name = unique_schema_migrations
tbl_name = schema_migrations
rootpage = 3
     sql = CREATE UNIQUE INDEX "unique_schema_migrations" ON 
"schema_migrations" ("version")

    type = table
    name = sqlite_sequence
tbl_name = sqlite_sequence
rootpage = 5
     sql = CREATE TABLE sqlite_sequence(name,seq)


Then I recreated all the tables:

/depot$ rake db:migrate
(in /Users/me/2testing/dir1/rails/depot)
==  CreateProducts: migrating 
================================================-- create_table(:products)
   -> 0.0019s
==  CreateProducts: migrated (0.0021s) 
=======================================
==  AddPriceToProduct: migrating 
=============================================-- add_column(:products, :price,
:decimal, {:precision=>8, :scale=>2,
:default=>0})
   -> 0.0118s
==  AddPriceToProduct: migrated (0.0122s) 
====================================
==  AddTestData: migrating 
=====================================================  AddTestData: migrated
(0.0127s)
==========================================
==  CreateSessions: migrating 
================================================-- create_table(:sessions)
   -> 0.0015s
-- add_index(:sessions, :session_id)
   -> 0.0004s
-- add_index(:sessions, :updated_at)
   -> 0.0004s
==  CreateSessions: migrated (0.0027s) 
=======================================
Then If I use this version of the find_cart method in the store 
controller:

class StoreController < ApplicationController
  def index
    @products = Product.find_products_for_sale
    now = Time.now
    @date = now.strftime("%m/%d/%Y")
    @time = now.strftime("%I:%M%p")
  end

  def add_to_cart
    product = Product.find(params[:id])
    @cart = find_cart
    @cart.add_product(product)
  end

#***********************
private
  def find_cart
     Cart.new
  end
#***********************
end

when I click on my "add to cart" button, a view displays the current 
item.  However, if I try to use sessions:

#***********************
private
  def find_cart
     session[:cart] ||= Cart.new
  end
#***********************

then I get the error message.  The only thing I haven''t tried is to 
delete my whole project and start over.




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