Re: Newbie: Composition by Association - Pagination Class general question.

Two things strike me as wrong with your thinking: (1) The idea that you have a separate DAO for each entity instead of a single generic DAO which can act for any entity in the system. (2) The idea that pagination requires its own class, and therefore needs this "is-a" and "has-a" nonsense. As for (1) even in my pre-OO days I was used to using a single generic DAO for all database access. The only time that more than one DAO existed was for a different DBMS engine. This is why I have one DAO class for MySQL, one for PostgreSQL and another for Oracle. If you are incapable of writing a single generic DAO then it just shows that you still have a lot to learn. For an idea on how this works take a look at http://www.tonymarston.net/php-mysql/databaseobjects.html As for (2) it should be obvious that pagination is not an entity in its own right that has its own properties and methods, it is merely a function which can be performed on any entity within the system. It should also be obvious that the requirements of pagination cannot be satisfied in a single class as some of the processing has to be handled in the presentation (UI) layer while the remainder is handled in the data access layer. The presentation layer needs a means to submit a request for a particular page number as well as the page size (rows per page). These two values are sent to the DAO which then translates them into values for LIMIT and OFFSET. After the DAO has issued the sql SELECT statement it needs to return two values - the current page number and the last available page number. The presentation layer then needs a mechanism to display these two values. This is explained in http://www.tonymarston.net/php-mysql/pagination.html If you still don't see how this works then you can run my sample application at http://www.tonymarston.net/php-mysql/sample-application.html You can even download the code so that you can step through it with your debugger. -- Tony Marston http://www.tonymarston.net http://www.radicore.org ""MEM"" <talofo@gmail.com> wrote in message news:000701ca0867$992912e0$cb7b38a0$@com... Hello, I have a Animals DAO class that I'd like to apply a pagination class to it. Between this two classes, there will be a composition relation (more precisely, an association one). My question is: Is a Pagination that "has a" Animal. OR Is a Animal that "has a" pagination? Should we create on Class Pagination a property named $_animal OR, should we create on class Animal a property named $_pagination? I'm inclined to accept the second one, since, if I put the property $_animal on my classe Pagination, I will end up, on the Pagination Class, with so many properties as pagination objects... :s Any help please? Márcio