Re: Dynamically adding a derived attribute
Re: Dynamically adding a derived attribute
- Subject: Re: Dynamically adding a derived attribute
- From: Chuck Hill <email@hidden>
- Date: Wed, 25 Apr 2007 21:52:08 -0700
This is how I have always done it:
// Remove as class property
NSMutableArray classProperties = new NSMutableArray
(columnEntity.classProperties());
classProperties.removeObject(dataAccessNotifications);
columnEntity.setClassProperties(classProperties);
Chuck
On Apr 25, 2007, at 9:23 PM, Lachlan Deck wrote:
Hi there,
I'm getting tired of manually adding to each entity a
'derivedCount' attribute defined as:
{
columnName = "";
definition = "count(*)";
externalType = BIGINT;
name = derivedCount;
valueClassName = NSNumber;
valueType = l;
},
So I'm attempting to add it when the application launches
(unsuccessfully so far) whilst the entity is loading.
I think the piece of the puzzle I'm missing is how to set this
attribute as a non-class property. Any ideas?
EOEntity anEntity; // assume exists
if ( anEntity.attributeNamed( "derivedCount" ) == null ) {
EOAttribute derivedCount;
derivedCount = new EOAttribute();
derivedCount.setValueType( "l" );
derivedCount.setExternalType( "BIGINT" );
derivedCount.setName( "derivedCount" );
derivedCount.setClassName( "java.lang.Long" );
derivedCount.setColumnName( "__temp__" );
anEntity.addAttribute( derivedCount );
derivedCount.setDefinition( "count(*)" );
derivedCount.setReadOnly( true );
}
No exceptions get thrown here, however when I attempt to do a fetch
it complains about the non-existing attribute in the schema.
Thanks.
with regards,
--
Lachlan Deck
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