Re: [GDL2] EODetailDataSource and EODisplayGroup

[David Ayers]

Dirk Lattermann wrote:
> Thank you, David, for your explanation, but unfortunately they do not
> help me much. I will try to explain what I want to do.

Hello Dirk,

Sorry for the late reply, I'm very busy currently.

> I intend to programmatically create a display group for a detail data
> source.

You are doing this with GDL2's EOInterface?  Well, to tell you the 
truth, I doubt we have the code in place for any of this to actually 
work, but I think Matt Rice has been filling in some blanks, so I may be 
wrong.  I only went through some primitive test cases when I started 
implementing it a while ago, but I've never used a UI with DB access yet.

> Until now in my test setups of EOInterface, I created all the interface
> elements (or have them awake from nib), then I created the data sources
> and display groups and connected everything together via associations.
> Then, before the user gets control, I told the data source(s) to fetch
> their data.
>
> Obviously, this isn't the way to go because the detail data sources get
> their editing context only after fetching data in their master data
> source, which qualifies the detail data source via an
> EOMasterDetailAssociation.
> But how can I proceed if I don't want to fetch before the UI is set up
> (e.g., if the user should be able to restrict the query before starting
> it)?

I think we need to use either some of the delegation methods or 
notifications to set this up from with EOInterface.  I was hoping to 
have a peel into how it should be done, but I just don't have the time 
right now.  But I've moved it to the top my TODO list, as soon as I've 
got some time.

> Even with an implementation of EOInterface that supported putting
> display groups, associations (and data sources) into a nib file,
> wouldn't this work only if fetchesOnLoad of the display group is set?

I think the EOMasterDetailAssociation will set the data source in the 
detail display group when the master display group changes selection... 
but this is just guessing right now.

> Or, when modelling everything in IB (I guess the detail data sources
> where created when dragging an EOMasterDetailAssociation from the
> palette and connecting it to the two display groups?), did IB fetch
> objects and qualify the detail data source
> before setting up the display group?
>
> There is a similar problem related to the last column display group
> implicitly created by EORecursiveBrowser which I'm implementing,
> but I fear my writing here is already confusing enough...

I'm really sorry I can't be of more help right now.  I'll get back to 
this as soon as I can.  Feel free to ask keep asking questions though, 
if I can quickly answer them, I will.  This one just needs some 
investigation which I just can't squeeze in right now.

Cheers,
David