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Posted by Tim Hunt on 12/19/07 12:33
On Dec 18, 5:31 pm, Gordon <gordon.mc...@ntlworld.com> wrote:
> I am currently working on some code for my CMS that creates a site
> folder, then creates all the necessary child folders inside it. The
> method that creates folders needs to insert into 2 tables so it wraps
> the operation in a transaction. (psuedocode below)
>
> public function createItem ($parent)
> {
> $this -> database -> beginTransaction ();
> $this -> database -> query ('INSERT INTO items (param1,
> param2 ... ) values (val1, val2 ... )');
> $newId = myMethodForGettingInsertId ();
> $this -> database -> query ('INSERT INTO folders (id, param3 ... )
> values ($newId, val3 ... )');
> $this -> database -> commit ();
> return ($newId);
>
> }
>
> (the real code is obviously a lot more sophisticated and has all the
> error checking and rollbacks and what have you but the mock up code
> below is clearer regarding the intent of the method)
>
> In my site creating class I have something along the lines of
>
> public function createItem ($parent)
> {
> $this -> database -> beginTransaction ();
> $newId = parent::createItem ($parent);
> parent::createItem ($newId, 'images');
> parent::createItem ($newId, 'css');
> parent::createItem ($newId, 'other_stuff');
> $this -> database -> commit ();
>
> }
>
> This obviously causes an exception. I can take the transaction code
> out of my folder class but the creation of a folder should be atomic.
> I could leave it out of the site creation class, but I really do need
> site creation to be atomic as well.
>
> Is there a way of determining that I am inside a transaction before
> attempting to start one?
Only if you keep track of it yourself, write your own
beginTransaction() and commit() methods and use a transaction count
variable.
All calls to your own beginTransaction() and commit() methods
increment/decrement the transaction counter respectively. Only the
first call to beginTransaction calls $this->database->beginTransaction
and $this->database->commit() is only called when the transaction
counter reaches 0 again.
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