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From Dave Lamy <davel...@gmail.com>
Subject Group function support
Date Tue, 09 Jun 2009 21:14:22 GMT
Hey guys-- I'm trying to get group functions operational in my
Cayenne-backed system.  As far as I can tell, the only support for group
functions (min, max, count, etc) outside of rolling my own SQL is EJBQL.. is
that true or am I missing something?

Assuming this is the case:  I'm having issues with my EJBQL working when I
reference a generic Cayenne class.  IE, my "Artist" data class doesn't have
a strong class implementation.. it just uses a standard base class.  This
feature has been great and is absolutely essential to our software.
However, in my test case I have a simple Artist class with no concrete impl:

<obj-entity name="Artist" lock-type="optimistic" dbEntityName="ARTIST"
superClassName="com.routeto1.data.DynamicDataObject">
        <obj-attribute name="address" type="java.lang.String"
db-attribute-path="ADDRESS"/>
        <obj-attribute name="name" type="java.lang.String"
db-attribute-path="NAME"/>
        <obj-attribute name="type" type="java.lang.String"
db-attribute-path="TYPE"/>
 </obj-entity>

 when I try to execute a simple EJBQL group test query:

select count(a), a.name from Artist a group by a.name

I get the following exception:

org.apache.cayenne.CayenneRuntimeException: [v.3.0M5 Nov 29 2008 21:12:47]
Can't perform lookup. There is more than one ObjEntity mapped to
com.routeto1.data.impl.DynamicDataObject
    at
org.apache.cayenne.map.EntityResolver._lookupObjEntity(EntityResolver.java:847)
    at
org.apache.cayenne.map.EntityResolver.lookupObjEntity(EntityResolver.java:701)
    at
org.apache.cayenne.query.BaseQueryMetadata.resolve(BaseQueryMetadata.java:99)
    at
org.apache.cayenne.query.SQLTemplateMetadata.resolve(SQLTemplateMetadata.java:47)
    at
org.apache.cayenne.query.SQLTemplate.getMetaData(SQLTemplate.java:157)
    at
org.apache.cayenne.access.jdbc.SQLTemplateAction.<init>(SQLTemplateAction.java:77)
    at
org.apache.cayenne.dba.JdbcActionBuilder.sqlAction(JdbcActionBuilder.java:90)
    at
org.apache.cayenne.access.jdbc.EJBQLAction.performAction(EJBQLAction.java:100)
    at
org.apache.cayenne.access.DataNodeQueryAction.runQuery(DataNodeQueryAction.java:57)
    at org.apache.cayenne.access.DataNode.performQueries(DataNode.java:236)
    at
org.apache.cayenne.access.DataDomainQueryAction.runQuery(DataDomainQueryAction.java:423)
    at
org.apache.cayenne.access.DataDomainQueryAction.access$000(DataDomainQueryAction.java:67)
    ....

which seems to read like the EJBQL impl doesn't support the generic base
class concept.  Am I right on this?  I don't care about EJBQL, just want to
get group functions working without having to resort to rolling a bunch of
dynamic SQL :-).  Perhaps an upgrade to M6 is in order?  Thanks in advance
for any help you can provide!

--Dave Lamy

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