Re: [CFCDev] object persistence

[Joseph Flanigan]

Suppose Person Object is an abstract object that has persistent data in 
multiple tables. For example, a contact of type person has zero or more 
telephone numbers. Each telephone number is of a type telephone number. In 
this case there are at a least 4 tables of data related to the person: 
contact, contact type, telephone and telephone type.  Person, because is 
has complex relations with telephone cannot be a simple flat table. It is 
disjointed and can only be joined by an external rule like a foreign 
key.  Consequently the application must provide data in sequences to 
satisfy the join rules.

In practice, I see abstract objects far more than simple objects.
(Also, consider in ColdFusion, data type binding between ColdFusion and 
database occur within the cfquery or cfstoredproc tags.

In the code generated with CFSQLTool, each table or  view has all the data 
access functions, like CRUD, within the CFC. These are called wrappers. 
Each wrapper function contains the SQL query and the data bindings. The 
collection of wrappers make up the  data access layer. The data access 
layer's specific job is to conduct transactions with the database.

Then, a convenient way to create an abstract object, like for person. is to 
create a CFC service object called person that invokes each of the wrappers 
as needed to implement the persistent data based on the business rule. The 
CFC service generator is also in CFSQLTool because I needed a way to handle 
disjoint abstract objects.

Joseph
At 01:32 PM 7/15/2004, you wrote:
I'm curious what approach people use for persisting objects in the db.
Let's say I have a Person object.  Is it better to have that Person object 
contain all of the Business methods to work on the object as well as the 
methods to persist itself or is it better to set up a separate PersonDAO 
object that deals with all of the database interactions and keep all 
database interaction out of the Person object?

Along those lines, I'm also curious how people actually do their 
updates.  Do you first update all of the properties of an object and then 
call a Persisit() method or when a setter method is called do you have it 
update the object property and then update that property in the db?  Seems 
like a lot of extra db traffic to do it the second way but it would cut 
down on some persistance logic.

I'm still a little new at working with CFCs in a more OO way so any help 
would be greatly appreciated.

Stephen
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