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Re: Bad eodelegate method?
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Re: Bad eodelegate method?


  • Subject: Re: Bad eodelegate method?
  • From: Chuck Hill <email@hidden>
  • Date: Tue, 11 Jul 2006 09:48:36 -0700


On Jul 11, 2006, at 9:23 AM, Randy Wigginton wrote:


I am getting a very strange error when I use my own EODelegate. For management reasons I am required to use MySQL. The PK support for MySQL out of the box for EOF is not thread safe; I can get duplicate IDs. Thus, I've created a very simple delegate, which looks like this:


public myEODelegate() {
EODatabaseContext.setDefaultDelegate(this);
}
private static NSArray keys = new NSArray("pk");
public NSDictionary databaseContextNewPrimaryKey(EODatabaseContext dbCtxt, Object object, EOEntity entity) {
NSArray keyNames = entity.primaryKeyAttributeNames();
if (keyNames.size()!=1)
return null;
String pkName = (String)keyNames.get(0);
try {
EOEditingContext ec = new EOEditingContext();
NSArray rawRows = EOUtilities.rawRowsForSQL(ec, "testit", "UPDATE EO_PK_TABLE SET pk=pk+1 where lower(name) ='"+entity.externalName().toLowerCase()+"'");
rawRows = EOUtilities.rawRowsForSQL(ec, "testit", "select pk from eo_pk_table where lower(name)='"+entity.externalName ().toLowerCase()+"'", keys);

That may be better than the default MySQL stuff, but you still have a race condition there. You need to do this in the context of a transaction.


			NSDictionary foo = (NSDictionary)rawRows.get(0);
			Long bd = (Long)foo.valueForKey("pk");

I suspect that this is your problem. Looking below, it seems that EOF is expecting an Integer.


			return new NSDictionary(bd, pkName);
		} catch (Exception e) { // Use default delegate
			return null;
		}
	}

The problem is this. I have a relationship, Owner and subguy. Owner has a primary key; subguy is owned by Owner. In the relationship, Owner propagates the primary key and owns the destination. Here is some code that will always fail:
allDelegate = new myEODelegate(); // turn on my delegate


		EOEditingContext ec = new EOEditingContext();
		NSLog.allowDebugLoggingForGroups(0x10000L);
		Owner	own = (Owner)EOUtilities.createAndInsertInstance(ec,"owner");
		Subguy gag = aag.sub();
		gag.setGoogleID(new Integer(1001));
		ec.saveChanges();
		gag.setContentBid(new Double(1.01));
		ec.saveChanges();

What is VERY strange is that if I delete the first saveChanges(), everything works. With it there, I get an exception:
<main> A fatal exception occurred: cannot update primary-key 'adGroupID' from '13' to '13' on object:{values = {googleID = 1001; contentBid = 1.01; adGroupID = 13; }; this = "<Subguy 8a3fe6 _EOIntegralKeyGlobalID[subguy (java.lang.Integer)13]>"; } of entity: subguy in databaseContext com.webobjects.eoaccess.EODatabaseContext@a08be5

Notice that this says _EOIntegralKeyGlobalID[subguy (java.lang.Integer)13] while your delegate returns a Long. The real message should probably be cannot update primary-key 'adGroupID' from '(java.lang.Integer)13]' to '(java.lang.Long)13]'.


Do the PK columns in the model have a Value Type of l (that is an L)? What happens if you convert the Long to an Integer in your delegate method?


Chuck


--
Coming sometime... - an introduction to web applications using WebObjects and Xcode http://www.global-village.net/wointro


Practical WebObjects - for developers who want to increase their overall knowledge of WebObjects or who are trying to solve specific problems. http://www.global-village.net/products/practical_webobjects




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