Re: [PHP] References in Sessions
On Thu, Oct 14, 2010 at 05:36:29PM +0200, Sebastian Detert wrote: > Alexander Schrijver schrieb: > >Is my message unclear? or didn't anyone ran into this problem? > > > If you want an atomic solution, you need to save the session to your > database. How often do you need to delete data? Isn't it better to > delete at night when noone is online, or logout all users for some > minutes while deleting? In addition to that I don't understand, why > it is important to prevent deletion if a point is selected ... If > you want to work with something that was deleted, print an error and > that's it. Yes, i can use a database. But i can't properly use the SESSION abstraction with a database. suppose i build a Session handler which writes to the database it needs to write to specific tables which contain the proper constraints. e.g. table session session_id (PK) table companies company_id (PK) session_id -> session(session_id) i.e. (one to many relationship) Thus $_SESSION['companies'] = Array(1,2,3) needs to be translated to insert a row in the companies table. Now suppose someone does $_SESSION['somethingwhichdoesnexist'] = 'bladiebla' (which is invalid) i can't make it properly fail. Because the Session handler is run at a later point. I can't find a method to properly work around this without rewriting to whole session handler. Doing deletions at night isn't solving the problem. Users can exist at night. Printing an error isn't solving the problem either. What kind of message should i print? "Something went wrong; i am not entirely sure what but it probably the administrator deleted or changed a the database. Oh, and your session is now useless". This seemed like an obvious problem to me with an obvious solution which i missed. Nobody has this problem? -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] References in Sessions
Alexander Schrijver schrieb: Is my message unclear? or didn't anyone ran into this problem? If you want an atomic solution, you need to save the session to your database. How often do you need to delete data? Isn't it better to delete at night when noone is online, or logout all users for some minutes while deleting? In addition to that I don't understand, why it is important to prevent deletion if a point is selected ... If you want to work with something that was deleted, print an error and that's it. -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] References in Sessions
Is my message unclear? or didn't anyone ran into this problem? -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] References in Sessions
On Mon, Oct 11, 2010 at 04:43:06PM +0200, Sebastian Detert wrote: > Why don't you write a small function checking for invalid IDs and > delete them and referenced subIDs? If you guess it's to hard/slow to > find out all referenced subIDs you could change your Session array > to an multi-dimensional array, with all referenced IDs on lower > levels > > array ( sector_id => array ( company_id => array (location_id) ) ); > > like > > array ( 1 => array (17,4 => array(2)) would mean that loction 2 > inside company 4 inside section 1 was selected. This way you only > need to delete an old entry, and all referenced IDs dissapear > > Sebastian Hi Sebastian, My explanation might've been unclear. The problem isn't deleting a row and its dependencies. The problem is that i can't delete both the reference from the database search trough all the sessions for references (using the file mechanism). And even if i could, it wouldn't be done atomically so it would be useless because a race could happen. I would like to have a function which either deletes a row, or if it is referenced by a session, fails. And if the session would be stored in the database MySQL could take care of this. However, the $_SESSION abstraction doesn't allow this to be implemented properly. I think an implementation is possible, it would however be very ugly. -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] References in Sessions
Alexander Schrijver schrieb: Hi list, I'm working on a project which uses a MySQL database to store some data. The database looks something like this: Companies - id (PK) - name - sector_id -> Sectors (id) - etc Locations - id (PK) - company_id -> Companies (id) - name - etc Sectors - id (PK) - name - etc And we're using a Session to store references (not actual PHP references ofcourse just the identifying integers) to these tables. For example a list of companies and locations which are selected in the GUI is kept in the session state. The session would look something like this when filled up. The integers are the PKs of the companies and sectors tables respectively. Companies = Array (1,2,3,4,etc) Sectors = Array (1,2,3,4,etc) The problem is: when there are 2 clients one administrative and one user, and the user has selected a company (or something else, it doesn't really matter). And then the administrative user comes along and deletes the row which the user just selected from the company table. There is an invalid reference in the Session of the user. I figured if I saved the session in the database and used constraints (foreign keys) to enforce this. This could work. However, the PHP session abstraction makes it very difficult to implement this properly. (I looked at session_set_save_handler) How do you guys deal with this problem? Thanks, Alexander Why don't you write a small function checking for invalid IDs and delete them and referenced subIDs? If you guess it's to hard/slow to find out all referenced subIDs you could change your Session array to an multi-dimensional array, with all referenced IDs on lower levels array ( sector_id => array ( company_id => array (location_id) ) ); like array ( 1 => array (17,4 => array(2)) would mean that loction 2 inside company 4 inside section 1 was selected. This way you only need to delete an old entry, and all referenced IDs dissapear Sebastian -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
