Re: EODataSource confusion :-(
Re: EODataSource confusion :-(
- Subject: Re: EODataSource confusion :-(
- From: Robert Walker <email@hidden>
- Date: Wed, 2 Feb 2005 18:25:29 -0500
Kieran,
EODataSource is basically a class that manages arrays of EOs. You
normally don't have to deal with them directly. What you should
concentrate on is how to manage your EOEditingContext. This is where
you insert, update, and delete objects. EOEditingContext is
responsible for managing your "object graph." The EODataSource, and
it's concrete subclasses EODatabaseDataSource, EODetailDataSource,
etc., are typically used by WODisplayGroups & EODisplayGroups to manage
arrays of EOs in an abstract manner. In other words, the display group
isn't concerned with where the EOs are coming from, they rely on the
associated EODataSource to manage that.
There are circumstances where it is useful to access data sources from
display groups, such setting behaviors on the underlying
EOFetchSpecification that is sometimes associated with the data source.
But I recommend worrying about that after you have mastered the
EOEditingContext.
On Feb 2, 2005, at 11:14 AM, Kieran Kelleher wrote:
Apologies for my elementary confusion....
Could someone briefly explain/advise what is the advantage of using
EODataSource objects instead of just an NSArray of objects? I did look
at the EODataSource concepts in the API docs, but still not sure
whether this is something "I should really be using to make WO
development easier"? Am I better off creating and setting an
EODataSource (setDataSource) when working with WODisplayGroups or
simply using an NSArray and setObjectArray?
With respect to EODatabaseDataSource, a point of confusion for me is
deleteObject: removes the object from the data source (but does it
literally delete the object permanently?)
insertObject: "The default implementation does nothing" ?! (So, what
does it do?) Parameters: the object to insert into the current editing
context (why would it not insert an object into the data source?)
Regards, Kieran _______________________________________________
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--
Robert Walker
www.robertwalker1.com
homepage.mac.com/robertwalker1
"There are 10 kinds of people in the world. Those who think in binary
and those who don't."
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