Re: [chiPHPug-discuss] OOP structuring question

[matt d. <mm_...@ya...>]

Hey Arlo,

It appears your objects are just representations of data tables?
In our system we use a base class row.inc that handles a lot of the data access and base functionality all classes need.
All other objects extend this class.

* The row class acts as a frame for a MySQL row 
* which provides a simple interface for accessing and saving data. When a descendent object is created, it loads
* the columns and all data of a particular row ID in a MySQL table into the row->columns and row->data
* members, respectively. To save, new values are loaded into the associated array row->data_pending,
* which the row->save() method uses. Upon saving, if a field in $data_pending is not equal to the same field in $data
* the validate() method is called, which a class derived from row can use to check or alter the new data.
* <p>
* Data is usually not accessed directly via the row->data array but instead is accessed using PHP5's method and parameter overloading, when an arbitrarily named $member of row is accessed (as in row->$member), row->__get() will be called which in turn calls row->$member(), if the method doesnt exist row->__call() will then be invoked. __call() takes the following steps: 1. check if row->data[$member] exists, if it does, that value is returned 2. invoke row->child_call($member).
* Usually row->child_call() is overloaded and the developer will use switch($member) to add their own methods or values for each particular type of table, the results of which should be stored in row->data within the child_call method (no value is returned).
*
So this function below basically accesses any column data or can be used to create a new function.
function child_call($nm,$argv) {
// cut and paste this when deriving new classes from row
$r = &$this->data[$nm]; // make a shorter alias
switch($nm) {
default:
unset($this->data[$nm]);
return -1;
}
}
If you want I'll send a more complete example but, basically we would use some other utilities like "getQueryObjects" which is like it sounds- so in your example a query would be "select * from photos where user_id = $ID" and you would tell  the function to return an array of photo objects.
 
$photos = getQueryObjects("select * from photos where user_id = $ID","photo");
 
Then we just use the convention <$= $photo->description() ?> if we want to display any of the row data or call a user defined function in the class.
 




________________________________
From: Arlo Leach <ar...@ar...>
To: Chicago PHP User Group <chi...@li...>
Sent: Wednesday, June 10, 2009 12:33:12 PM
Subject: [chiPHPug-discuss] OOP structuring question

Hi folks,

I'm doing my first project with a fully object-oriented approach and I have
a question about how you all would break the code apart.

Let's say I have a social networking site where members can upload photos,
and I want to display a particular member's photos.

One approach is to have a Member object, with a method getPhotos, that
returns the IDs of the photos that belong to that member; and to have a
Photo object, with a method getDetails, that returns the details for a given
photo. In order to display a member's photos, I would first call getPhotos
for the member, then call getDetails for each of the returned photos. This
makes sense from an encapsulation perspective, but it seems wasteful because
I'd have one initial database query plus an additional query for each photo.

I could build getDetails so that it can take a list of IDs and return the
details for all the photos at once, and then I'd just have two queries. Or I
could build a getPhotosByMember method that accepts a member ID as an
argument and returns the details for all the photos belonging to that
member. Then I'd be down to one query, but I would probably end up building
several similar methods (e.g., getRecentPhotos) that would have redundant
code.

What would you say is the normal or accepted way to structure this?

Thanks,
-Arlo 

_______________________________

Arlo Leach
773.769.6106
http://arlomedia.com




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