It's not thread safe, and Wonder's implementation doesn't actually
work like this anymore (your code is based on a version from last year
sometime) ... See
ERXEOControlUtilities._aggregateFunctionWithQualifier for an example
of how to do it properly (we actually create an attribute without
adding it to the entity)
ms
On Mar 30, 2008, at 5:43 PM, Dov Rosenberg wrote:
We have some code that we are using from Project Wonder (I think)
that adds an attribute programmatically to an EOEntity to do things
like count, max, etc. (See below). We were doing a load test on our
application and started throwing errors because a different query
was submitted using the extra attribute. It seems that making
changes to the EOModel is not thread safe. If that is the case is
there anything we can do to use this code? Or should we dump this
and build a regular fetch for the aggregate data. Any thooughts or
insights would be a huge help.
Query that was generated in error – notice the COUNT() attribute
embedded in the query incorrectly
"SELECT t0.ACTUALRATING, t0.BODY, t0.CLOSED, t0.DATEADDED,
t0.DATEMODIFIED, t0.FORUMID, t0.IPADDRESS, t0.LOCALEID, t0.MODERATE,
COUNT(t0.RECORDID), t0.PUBLISHED, t0.RECORDID, t0.STATUS, t0.TITLE,
t0.TYPE, t0.USERID, t0.USERNAME, t0.USERNICKNAME, t0.WEIGHTEDRATING
FROM DBTOPIC t0 WHERE t0.RECORDID = ?" withBindings:
1:"0032274bc94901122623a943007f46"(recordID)>:
Next exception:SQL State:42000 -- error code: 937 -- msg:
ORA-00937: not a single-group group function
This is the code that we use to add the temporary attribute.
public static Number
aggregateNumberFunctionWithQualifier(EOEditingContext ec, String
entityName, String attributeName, String function, EOQualifier
qualifier) { EOEntity entity = EOUtilities.entityNamed(ec,
entityName); NSArray results = null; EOAttribute
attribute = createAggregateAttribute(ec, function, attributeName,
entityName, "java.lang.Number", "i"); EOQualifier
schemaBasedQualifier =
entity.schemaBasedQualifier(qualifier); EOFetchSpecification
fs = new EOFetchSpecification(entityName, schemaBasedQualifier,
null); synchronized (entity)
{ entity.addAttribute(attribute);
try{ fs.setFetchesRawRows(true);
fs.setRawRowKeyPaths(new NSArray(attribute.name()));
results =
ec
.objectsWithFetchSpecification
(fs
); }finally
{ entity
.removeAttribute(attribute); } } if
((results != null) && (results.count() == 1))
{ NSDictionary row = (NSDictionary)
results.lastObject(); if
(row.objectForKey(attribute.name()) != null &&
row.objectForKey(attribute.name()) instanceof Number)
{ return (Number)
row.objectForKey(attribute.name()); } }
return null; }
Dov Rosenberg
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