Re: Core Data Rookie
Re: Core Data Rookie
- Subject: Re: Core Data Rookie
- From: Andrew Shamel <email@hidden>
- Date: Fri, 22 Jul 2005 08:59:06 -0400
On Jul 21, 2005, at 8:13 PM, mmalcolm crawford wrote:
On Jul 21, 2005, at 4:55 PM, Andrew Shamel wrote:
And one more email from a clueless new Core Data programmer...
My problem is this: I want to create an application that keeps
track of recipes. I have done this handily so far, up to the
handling of the ingredients. I want the UI to have a column
listing the various recipes, and a table listing the ingredients
for the selected recipe.
The application's data model contains two entities: Recipe and
Ingredient. As it stands now, each entity has a reciprocal
relationship to the other, on the order of "recipes" and
"ingredients." The relationship from Recipe to Ingredient is one-
to-many, and the relationship from Ingredient to Recipe is one-to-
one, as a recipe has many ingredients, but each ingredient has
only one recipe.
Thus far, I have been able to make the Ingredients table display
ALL of the ingredients created, but I am having trouble figuring
out how to set an ingredient's recipe relationship to point to the
selected recipe, and likewise, how to make the ingredients table
display only those that belong to the selected recipe.
My guess is that I lack a sufficient understanding of Core Data.
I've looked at any number of Apple documentation pages, and have
done Cocoa Dev Central's Core Data tutorial. The trouble is, the
tutorial is really just a walk-through, and it doesn't do much in
the way of explaining what's actually going on.
This really has very little to do with Core Data. It's a question
of how you are controlling your objects. You haven't said how you
are managing your table views, how you determine your selection and
so on. From this perspective, Core Data managed objects behave in
exactly the same way as any other Cocoa objects. If you're using
bindings to manage your user interface, simply use your array
controller's 'selection' and follow key paths, just as you would
non-Core Data objects. An example (that uses Core Data, but an
object rather than an array controller) is given in <http://
developer.apple.com/documentation/Cocoa/Conceptual/
NSPersistentDocumentTutorial/index.html>.
An entire "recipes" sample application is given at <http://
developer.apple.com/samplecode/CoreRecipes/CoreRecipes.html>.
mmalc
Thanks so much!
--a
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