Proper Design

  • Thread starter Thread starter John
  • Start date Start date
J

John

Hi there,

I am writing a simple program that will connect to database.
Database has 2 tables, let's call them father and child.
This is one to many relationship.
I would like to create corresponding classes for each table.
Each class would have functions Insert, Edit, Delete
I would like to find some information how to properly design my classes.

I used to program in php and delphi.
So I used to create separe class that corresponded to each table in
database.
In Father class I used to crate an array of child.
whenever Father was inserting new record to database, it was also inserting
corresponding record(s) into child.

I can easly do it, but would like to find out what is the best way to do it.

For instance, if there are 2 tables in database (father and child)
Father has
Id Integer
FatherName String

Child has
Id Integer (corresponds to father Id)
ChildName String

How to design 2 classes fot both tables?

Thanks,
John
 
I can easly do it, but would like to find out what is the best way to
do it.

For instance, if there are 2 tables in database (father and child)
Father has
Id Integer
FatherName String

Child has
Id Integer (corresponds to father Id)
ChildName String

How to design 2 classes fot both tables?
Click to expand...

You can use a Typed Dataset... or take a look at an ORM mapper. Saves you
the troble of writing your own classes. I personally use LLBLGen Pro (very
well reviewed). There are other projects out there like NHibernate,
CodeSmith, etc.
 
There are a bunch of ways to do this. You might want to check out Deborah
Kurata's new book, "Doing Objects in VB2005". It shows how to use the
3-layer methodology, separating your business layer from your data layer
from your UI layer. It also shows how to design your data and set up
corresponding classes and their methods and properties. I found it hugely
understandable and helpful.

For this case, I would do this:

-- set up a class for Father
-- set up a class for Child
-- set up a class for ChildList that is a list of children

On the ChildList class, I would do one of two things.

If you are ever going to want to see a list of children for more than one
father, make one of the properties of the Child class the FatherID, and
then every entry in the ChildList will have its associated FatherID. If you
do this, you want to make the default constructor for ChildList load all of
them, but you want another constructor that just loads the children for a
specified FatherID.

If you are only ever going to want to see a ChildList for a specific
Father, put the FatherID property in the ChildList class, and just have
one, versus one for each Child in the list. In this case, I would make the
default constructor private, and add a constructor that accepts FatherID.
This way, you can't accidentally instantiate ChildList w/o giving the
Father.

If you are always going to want to see the ChildList with the Father, add a
property to the Father class that holds a ChildList. Otherwise, just
define it wherever you're going to use it.

Hope this helps. If you need more info, or specific code, post back.

Robin S.
 
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