Re: Attempt to insert null key into a com.webobjects.foundation.NSMutableDictionary
Re: Attempt to insert null key into a com.webobjects.foundation.NSMutableDictionary
- Subject: Re: Attempt to insert null key into a com.webobjects.foundation.NSMutableDictionary
- From: Jevon Hills <email@hidden>
- Date: Thu, 15 May 2003 08:28:10 -0600
On Wednesday, May 14, 2003, at 04:18 PM, Art Isbell wrote:
On Wednesday, May 14, 2003, at 11:58 AM, Jevon Hills wrote:
Sorry Art, I'm still learning. What do you mean 'underlying
relationships of a flattened relationship are class properties'?
A flattened relationship spans an entity that's related to the source
and destination entities of the flattened relationship. If you look
at the definition of the flattened relationship, you'll see that it's
comprised of a couple of relationships. These relationships shouldn't
be class properties.
I have two tables joined by a 'link table' , I flattened the
relationship in eomodeler by selecting the CollectionDesc entity,
them the relationship to Collection (the link) and then the
relationship to Content and flattened on that so that now my
CollectionDesc has methods to set/get Content objs.
Have I done that part correctly??
Possibly not. You should allow EOModeler to create this many-to-many
relationship for you. Select the model entry at the top of the
entities list in the left pane of EOModeler. In the right page will
be the list of entities in the model. Command-select (or if Windows,
do whatever supports multiple selections) the CollectionDesc and
Content entities. In EOModeler's menu, click "Join in Many to Many"
(not sure of the exact wording). This will create the join entity,
CollectionDescContent, and all of the necessary relationships. But
you'll notice that CollectionDesc.collectionDescContents and
Content.collectionDescContents are not class properties. If you need
to follow these relationships in your app to access
CollectionDescContent, then you'll have to delete the flattened
relationship and make these relationship class properties because the
flattened and underlying relationships can't all be class properties.
You'll probably want to replace the Collection entity with
CollectionDescContent.
I have just created the CollectionDescContent by allowing EOModeler to
perform the "join in Many to many", but I'm unsure of a few things,
and perhaps this is because I did not give enough of the right info at
the beginning for you.
First the more I learn about EOModeler the more I try to find a way to
get training on WO. I only know what I've learned using online/web
tutorials and books. Apparently that just scratched the surface.
Thank-you for your help I do really appreciate it.
Now for more of how I'm confused. I probably did not state at the
beginning that I'm working using a corporate database, which is not
only used for WO, but by several different tools. As a result I the
relation ship of CollectionDesc<-->>Collection<<-->Content is that of
3 tables which I have to use/maintain.
So having followed your instructions I have the following questions:
Can I get CollectionDescContent entity that EOModeler created to
maintain the table of Collection for me?
As far as terminology, can you direct me to a good source on the Web
which can help me better understand 'Properties' and other elements of
WO? Up until now I assumed, and it appears incorrectly, that
Properties were synonymous with "Attributes", "Member Data", "Fields"
(.NET lingo).
As far as reference materials that I have on hand: WebObjects
Developer's Guide by Ravi Mendis, Building WebObjects 5 Applications by
Jesse Feiler, Professional WO 5 (Wrox Press). Are there any others you
would recommend?
Wow, sorry about the lack of cohesion.
Jevon
'Hungry for Knowledge'
Aloha,
Art
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Jevon K. Hills
Developer - Zymeta Media Promotion Systems
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