Rails - Jun 2006 - how can I control when to commit a transaction?

hello

it seems like this question has appeared a few times with no answer:

how do you get rails to issue ''write'' statements (ie
''CREATE/UPDATE'') to
the database without committing each time?

I tried setting

ActiveRecord::Base.connection.begin_db_transaction

before calling any action on my object, but as soon as

myObject.save
or
myObject.update

is called, rails will issue a ''commit'' after the
''CREATE'' or ''UPDATE''.

The example given in the rails doc does not work for my application 
because I cannot enclose my actions in a block (the user is allowed to 
call several methods in the controller before committing).

So far I had to use update_all with a where condition. Are there other 
methods that will issue an UPDATE statement without immediately sending 
a COMMIT?

thanks for any hints

Isabelle

-- 
Posted via http://www.ruby-forum.com/.

On Jun 1, 2006, at 9:00 AM, iphan iphan wrote:
> The example given in the rails doc does not work for my application
> because I cannot enclose my actions in a block (the user is allowed to
> call several methods in the controller before committing).
>
> So far I had to use update_all with a where condition. Are there other
> methods that will issue an UPDATE statement without immediately  
> sending
> a COMMIT?
Long-running transactions in web apps are painfully unnecessary: keep  
the record under edit in session; save it when the user chooses to  
commit; employ optimistic locking to detect and resolve conflicts.

If you insist on riding the client/server dinosaur and can tolerate  
coding against a fluid private API ;) then do
   model.save_without_transactions(true)

jeremy

thanks Jeremy, this is very helpful.
> keep
> the record under edit in session; save it when the user chooses to
> commit; employ optimistic locking to detect and resolve conflicts.
is it possible to perform validation with this method? The scenario: my 
object has several 1-n associations

- user edits object itself
- ''update'' saves record without commit *if it is valid*
- user edits associated objects
- ...etc...
- ''save'' commits to database / ''undo all''
restores previous state

validation on step2 would prevent further edits to be lost if the commit 
fails over a constraint violation.

The reason I do not want to commit each time: I need to have the 
application behave like a text editor, i.e. nothing is kept if the work 
is not saved. My users  have requested that they can control when to 
save and when not.

This is so that other users can follow the changes, just like in a cvs 
repository. And in this case, one does *not* commit after every single 
change.

I guess the difference is that my object is not a single file, but 
several tables :-(

Isabelle

-- 
Posted via http://www.ruby-forum.com/.

Isabelle, you''ll want to do something like this....

(snippet from order saving in my project substruct)

# Does a creation of all required objects from a form post
  #
  # Each model is created and validated at the beginning.
  # This assures all errors show up if even if the begin...rescue...end
  # block skips save! of a model.
  #
  # Does transaction to create a new order.
  #
  # Will throw an exception if there is a problem, so be sure to handle that
  def create_order_from_post
    @use_separate_shipping_address = params[:use_separate_shipping_address]

    @order_user = OrderUser.new(params[:order_user])
    @order_user.valid?

    @order = Order.new(params[:order])
    @order.valid?

    @billing_address = OrderAddress.new(params[:billing_address])
    @billing_address.valid?

    @shipping_address = OrderAddress.new(params[:shipping_address])
    if @use_separate_shipping_address
      @shipping_address.valid?
    end

    @order_account = OrderAccount.new(params[:order_account])
    @order_account.valid?

    OrderUser.transaction do
      @order_user.save!
      Order.transaction do
        @order = @order_user.orders.build(params[:order])
        @order.order_number = Order.generate_order_number
        @order.save!
      end
      OrderAddress.transaction do
        # Addresses
        @billing_address
@order_user.order_addresses.create(params[:billing_address])
        @billing_address.is_shipping = true
        @billing_address.save!
        if @use_separate_shipping_address then
          @shipping_address
@order_user.order_addresses.create(params[:shipping_address])
          @shipping_address.is_shipping = true
          @billing_address.is_shipping = false
          @billing_address.save!
          @shipping_address.save!
        end
      end
      OrderAccount.transaction do
        @order_account = OrderAccount.new(params[:order_account])
        @order_account.order_user_id = @order_user.id
        @order_account.order_address_id = @billing_address.id
        @order_account.save!
      end
    end
  end

On 6/1/06, iphan <iphan@isb-sib.ch> wrote:
>
> thanks Jeremy, this is very helpful.
>
> > keep
> > the record under edit in session; save it when the user chooses to
> > commit; employ optimistic locking to detect and resolve conflicts.
>
> is it possible to perform validation with this method? The scenario: my
> object has several 1-n associations
>
> - user edits object itself
> - ''update'' saves record without commit *if it is valid*
> - user edits associated objects
> - ...etc...
> - ''save'' commits to database / ''undo
all'' restores previous state
>
> validation on step2 would prevent further edits to be lost if the commit
> fails over a constraint violation.
>
> The reason I do not want to commit each time: I need to have the
> application behave like a text editor, i.e. nothing is kept if the work
> is not saved. My users  have requested that they can control when to
> save and when not.
>
> This is so that other users can follow the changes, just like in a cvs
> repository. And in this case, one does *not* commit after every single
> change.
>
> I guess the difference is that my object is not a single file, but
> several tables :-(
>
> Isabelle
>
> --
> Posted via http://www.ruby-forum.com/.
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>


-- 
seth at subimage interactive
http://www.subimage.com/sublog/
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Jeremy Kemper wrote:
> If you insist on riding the client/server dinosaur and can tolerate
> coding against a fluid private API ;) then do
>    model.save_without_transactions(true)
this method is not documented anywhere. I did a search on the Edge
documentation and could not find it.

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