Re: Using prototypes with more than one EOModel and different databases

What I do:  I have an EOModel in a framework, that will be used by 
different applications. Some applications connect to one db, some to 
another. All individual applications, however, will only be used with one 
db.  [Or at least individual app instances will only be used with one db; 
no app instance needs to switch back and forth; it knows when it launches 
with db it will talk to].

In this situation, it works well for me to change the external types of the 
EOPrototype at run-time, on model load.  Here is some code I use:

1. I have a dictionary in the Application that maps from the prototype 
attribute names to the proper external type:
         prototypeOverrides = new NSMutableDictionary();
         //eg: "integerType" is the name of my prototype attribute.
         //"NUMBER" is the proper external type, in this case for Oracle.
         prototypeOverrides.setObjectForKey("NUMBER", "integerType");
         prototypeOverrides.setObjectForKey("DATE", "datetimeType");
         prototypeOverrides.setObjectForKey("LONG", "longtextType");
         prototypeOverrides.setObjectForKey("VARCHAR2", "varcharType");

2. I register to receive the model added notification in the app constructor:
         Class params[]={com.webobjects.foundation.NSNotification.class};
         NSSelector selector=new 
NSSelector("receiveModelAddedNotification", params);
         NSNotificationCenter.defaultCenter().addObserver(this, selector, 
EOModelGroup.ModelAddedNotification, null);

3. In application, this method receives the notification and acts upon it 
thusly:
    public void receiveModelAddedNotification(NSNotification notification) {
         EOModel model = (EOModel) notification.object();

         // We use EOF prototype feature so we can easily change external
         // types to be appropriate to Oracle.
         EOEntity prototypeEntity = model.entityNamed("EOJDBCPrototypes");
         if (prototypeEntity != null) {
                 java.util.Enumeration eachPrototypeEnumer 
=                prototypeOverrides.allKeys().objectEnumerator();
                     while (eachPrototypeEnumer.hasMoreElements()) {
                         String prototypeName = (String) 
eachPrototypeEnumer.nextElement();
                         String properExternalType =
                            (String) 
prototypeOverrides.objectForKey(prototypeName);
                         EOAttribute prototypeAttribute = 
entity.attributeNamed(prototypeName);
                         prototypeAttribute.setExternalType(properExternalType);
                         }
         }
     }


At 07:40 PM 12/2/2002 -0800, Chuck Hill wrote:
>Hi Stefan,
>
>At 11:34 AM 02/12/2002 +0100, Stefan Apelt wrote:
> >Hi,
> >
> >I   have  two  EOModels  in  a  project  that  are  used  to  maintain
> >user-specific  and  content-specific  data.  In  one EOModel I have an
> >'EOPrototypes' entity that contains all prototypes for both models.
> >
> >Both  models  now  connect  to the same database but in the future, it
> >should  be  possible to connect to two different databases (say, mySQL
> >and  FrontBase).  Has anyone tried this and can tell how to handle the
> >prototypes  thingy  then?  Changing the connection dictionary is not a
> >problem,  it  is  the  external  types (varchar vs. TEXT) that I worry
> >about.
> >
> >I have a few guesses but wanted to ask first before reinventing the
> >wheel:
> >
> >1. It does not work. Stick with one database server. My idea for now.
> >
>Possibly the case.
>
> >2. Have one EOPrototype entity per EOModel. Might not work because of
> >   a naming conflict in the EOModelGroup later.
> >
>I'm certain this will not work.  I've tried it by accident.  ;-)
>
>
> >3. Have separate EOModelGroups, each with one model. Might not work
> >   with WO because it loves its defaultModelGroup best.
> >
>This should work as long as there are no unfortunate references to
>defaultModelGroup.  I don't know if you can make cross model group
>relationships thought.
>
>
> >4. Another cool solution I have not seen yet...
> >
>Some other ideas off the top of my head:
>1. Name the prototypes differently in each model (userLongString,
>contentLongString).  This could be combined with the code to create the
>EOPrototypes Entity on the fly (from Jonathan Rochkind?) from a config file
>that was previously posted to the list.
>
>2. Use public void setPrototype(EOAttribute prototype) on EOAttribute to
>set the prototypes manually.
>
>
>
>Chuck
>
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