Hi Kevin,
I did poke inside the ERXExistsQualifier to see… seems that it doesn’t properly
handle a “flattened” relationship. When you say “flattened” you mean there is
another EO join table in there that is hidden correct? Yeah, it seems to be a
shortcoming of ERXExistsQualifier.
You *could* create some unflattened relationships and use those instead, then
you could still use exists qualifier.
While your new qualifier doesn’t throw an error, I don’t think it does what you
want. Your new qualifier would probably work better like this:
public static EOQualifier visibleToAccountQualifier(Account account)
{
EOQualifier qualifier = new ERXOrQualifier(
account.identityQualifier(false),
Account.TEAMS.has(account.teams())
);
return new ERXExistsQualifier(qualifier, Profile.ACCOUNT.key());
}
Notice the subtle difference. The “identity” qualifier will happen all the
time… you’ll want that because even if you have teams it might just be “you”
directly.
Wow, that is nice and easy. AND, now that I understand your situation better,
makes sense. You traverse the flattened relationship right at “account.teams()”
to get the set of teams that could possibly point back to your Account.
Very nice. Should perform well. Now try the following:
public static EOQualifier visibleToAccountQualifier(Account account)
{
boolean useInClauseInstead = false;
EOQualifier qualifier = new ERXOrQualifier(
account.identityQualifier(false),
Account.TEAMS.has(account.teams())
);
return new ERXExistsQualifier(qualifier, Profile.ACCOUNT.key(),
useInClauseInstead);
}
Play with the true / false value of “useInClauseInstead” to see what is faster
for your data set.
Have fun! :-)
AARON ROSENZWEIG / Chat 'n Bike
e: [email protected] t: (301) 956-2319
On Apr 16, 2014, at 3:13 PM, Kevin Hinkson <[email protected]> wrote:
> Thanks for your help Aaron,
>
> Your identity qualifier suggestion was extremely helpful. I was entirely
> unaware of the EOEntity method qualifierForPrimaryKey so learning about that
> makes so many things much easier.
>
> I've updated to the latest WebObjects changes in the master branch. I think
> I'm starting to get the hang of the ERXExistsQualifier, after taking a look
> at your example and at the presentation here
> http://www.chatnbike.com/presentation_existsQualifier/.
>
> I'm still having a problem with one aspect of it —
> Account.TEAMS.dot(Team.ACCOUNTS).key() this key path is a flattened to many
> relationship that is "looking back on itself" if that makes any sense, and
> the EOSQLExpression class has some difficulty generating a SQL statement that
> will work for that situation. It always seems to happen no matter how I
> arrange it as long as I'm trying to work with a to many relationship in that
> way.
>
> Here's the stack trace that generates:
>
> ERROR 06:21:28
> (com.webobjects.eoaccess.ERXEntityDependencyOrderingDelegate:101)
> -Unexpected non-EOGeneralAdaptorException exception
> java.lang.NullPointerException
> at
> er.extensions.eof.qualifiers.ERXExistsQualifier$ExistsQualifierSQLGenerationSupport.sqlStringForSQLExpression(ERXExistsQualifier.java:256)
> at
> com.webobjects.eoaccess.EOQualifierSQLGeneration$Support._sqlStringForSQLExpression(EOQualifierSQLGeneration.java:165)
> at
> com.webobjects.eoaccess.EOSQLExpression.prepareSelectExpressionWithAttributes(EOSQLExpression.java:997)
> at
> com.webobjects.jdbcadaptor.JDBCExpression.prepareSelectExpressionWithAttributes(JDBCExpression.java:146)
> at
> com.webobjects.jdbcadaptor.PostgresqlExpression.prepareSelectExpressionWithAttributes(PostgresqlExpression.java:770)
> at
> er.extensions.eof.qualifiers.ERXExistsQualifier$ExistsQualifierSQLGenerationSupport.sqlStringForSQLExpression(ERXExistsQualifier.java:266)
> at
> com.webobjects.eoaccess.EOQualifierSQLGeneration$Support._sqlStringForSQLExpression(EOQualifierSQLGeneration.java:165)
> at
> com.webobjects.eoaccess.EOSQLExpression.sqlStringForArrayOfQualifiers(EOSQLExpression.java:1528)
> at
> com.webobjects.eoaccess.EOSQLExpression.sqlStringForDisjoinedQualifiers(EOSQLExpression.java:1574)
> at
> com.webobjects.eoaccess.EOQualifierSQLGeneration$_OrQualifierSupport.sqlStringForSQLExpression(EOQualifierSQLGeneration.java:578)
> at
> com.webobjects.eoaccess.EOQualifierSQLGeneration$Support._sqlStringForSQLExpression(EOQualifierSQLGeneration.java:165)
> at
> com.webobjects.eoaccess.EOSQLExpression.prepareSelectExpressionWithAttributes(EOSQLExpression.java:997)
> at
> com.webobjects.jdbcadaptor.JDBCExpression.prepareSelectExpressionWithAttributes(JDBCExpression.java:146)
> at
> com.webobjects.jdbcadaptor.PostgresqlExpression.prepareSelectExpressionWithAttributes(PostgresqlExpression.java:770)
> at
> com.webobjects.eoaccess.EOSQLExpressionFactory.selectStatementForAttributes(EOSQLExpressionFactory.java:225)
> at
> com.webobjects.jdbcadaptor.JDBCChannel.selectAttributes(JDBCChannel.java:213)
> at
> er.extensions.jdbc.ERXJDBCAdaptor$Channel.selectAttributes(ERXJDBCAdaptor.java:203)
> at
> com.webobjects.eoaccess.EODatabaseChannel._selectWithFetchSpecificationEditingContext(EODatabaseChannel.java:897)
> at
> com.webobjects.eoaccess.EODatabaseChannel.selectObjectsWithFetchSpecification(EODatabaseChannel.java:234)
> at
> com.webobjects.eoaccess.EODatabaseContext._objectsWithFetchSpecificationEditingContext(EODatabaseContext.java:3055)
> at
> com.webobjects.eoaccess.EODatabaseContext.objectsWithFetchSpecification(EODatabaseContext.java:3195)
> at
> com.webobjects.eocontrol.EOObjectStoreCoordinator.objectsWithFetchSpecification(EOObjectStoreCoordinator.java:488)
> at
> com.webobjects.eocontrol.EOEditingContext.objectsWithFetchSpecification(EOEditingContext.java:4069)
> at
> er.extensions.eof.ERXEC.objectsWithFetchSpecification(ERXEC.java:1308)
> at
> com.webobjects.eocontrol.EOEditingContext.objectsWithFetchSpecification(EOEditingContext.java:4444)
> at
> co.coralstone.apparatus.synchronization.data.eo._Profile.fetchProfiles(Unknown
> Source)
> at
> co.coralstone.apparatus.synchronization.service.Application.finishInitialization(Unknown
> Source)
> at
> er.extensions.appserver.ERXApplication.finishInitialization(ERXApplication.java:1296)
> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> at
> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> at java.lang.reflect.Method.invoke(Method.java:606)
> at
> com.webobjects.foundation.NSSelector._safeInvokeMethod(NSSelector.java:122)
> at
> com.webobjects.foundation.NSNotificationCenter$_Entry.invokeMethod(NSNotificationCenter.java:588)
> at
> com.webobjects.foundation.NSNotificationCenter.postNotification(NSNotificationCenter.java:532)
> at
> com.webobjects.foundation.NSNotificationCenter.postNotification(NSNotificationCenter.java:546)
> at com.webobjects.appserver.WOApplication.run(WOApplication.java:1229)
> at
> er.extensions.appserver.ERXApplication.run(ERXApplication.java:1417)
> at com.webobjects.appserver.WOApplication.main(WOApplication.java:548)
> at
> er.extensions.appserver.ERXApplication.main(ERXApplication.java:861)
> at
> co.coralstone.apparatus.synchronization.service.Application.main(Unknown
> Source)
> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> at
> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> at java.lang.reflect.Method.invoke(Method.java:606)
> at com.webobjects._bootstrap.WOBootstrap.main(WOBootstrap.java:87)
>
>
> The following qualifier does work. I'm not sure it is ideal but it works and
> I'll probably evolve it as I gain a better understanding of how the Exists
> Qualifier works.
>
> public static EOQualifier visibleToAccountQualifier(Account account)
> {
> EOQualifier qualifier = null;
> NSArray<Team> teams = account.teams();
> if (true == teams.isEmpty())
> {
> // if the account is not a member of any teams, then just get
> the profiles for this account
> qualifier = account.identityQualifier(false);
> }
> else
> {
> // otherwise since we have the account, use their teams in the
> qualifier instead of traversing the to-many as before
> qualifier = ERXQ.has(Account.TEAMS_KEY, account.teams());
> }
> return new ERXExistsQualifier(qualifier, Profile.ACCOUNT.key());
> }
>
>
> On 15 Apr 2014, at 12:30, Aaron Rosenzweig <[email protected]> wrote:
>
>> Hello Kevin,
>>
>> I’ll take a swing at a new qualifier for you.
>>
>> Verbally:
>> A profile sometimes points directly to the account I want. Other times, the
>> primary account for a profile is NOT the one I want but it has teams which
>> vicariously point back to the account I want. Give me all those profiles.
>>
>> Style notes (entirely optional):
>> Try to avoid starting with “ERXQ.anything” such as “ERXQ.or()” and
>> “ERXQ.keypath()” Technically it is ok but it’s harder to rest and disrupts
>> the visual flow of the code.
>>
>> Don’t use “_KEY” - It’s easier to just call “.key()” when you need it as
>> you’ll soon see.
>>
>> Code sniff:
>> Anytime you have a to-many relationship involved, consider an “exists”
>> qualifier.
>>
>> Utility method:
>> You need a way to “qualify yourself.” Your primary keys are probably hidden
>> (rightly so). You don’t want to qualify on “name”, “title”, “description" or
>> anything else since you already have the Account object you want in hand. So
>> put this utility method either in your “Account” EO or preferably in your
>> abstract parent class if you have one (between “Account” and
>> “ERXGenericRecord”):
>>
>> public EOQualifier identityQualifier() {
>> EOEntity entity =
>> ERXEOAccessUtilities.entityNamed(editingContext(), entityName());
>> EOQualifier qualifier =
>> entity.qualifierForPrimaryKey(primaryKeyDictionary(false /*inTransaction*/));
>> return qualifier;
>> }
>>
>> The new code:
>>
>> // Generates a qualifier for the Profile for this account and the Profiles
>> of any account on the same team (or that is the intention)
>> public static EOQualifier visibleToAccountQualifier(Account account)
>> {
>> EOQualifier accountIsDirectlyTheOneIWantQualifier =
>> account.identityQualifier();
>> EOQualifier accountHasTeamForTheOneIWantQualifier = new
>> ERXExistsQualifier (
>> account.identityQualifier() /*subQualifier*/,
>> Account.TEAMS.dot(Team.ACCOUNTS).key() /*baseKeyPath*/,
>> );
>> EOQualifier finalAccountQualifier = new ERXOrQualifier(
>> accountIsDirectlyTheOneIWantQualifier,
>> accountHasTeamForTheOneIWantQualifier);
>>
>> EOQualifier profileQualifier = new ERXExistsQualifier (
>> finalAccountQualifier /*subQualifier*/,
>> Profile.ACCOUNT.key() /*baseKeyPath*/, /*Note: this is a to-one
>> relationship, but that’s ok*/
>> );
>>
>> return profileQualifier;
>> }
>>
>>
>> Wrap-up:
>>
>> Note: be sure to either update Wonder or at least “cherry pick" the latest
>> version of the ExistsQualifier.
>>
>> Kevin give this a try and report back. It’s funny how the ExistsQualifier
>> can solve 90% of the complex data-mining queries we could encounter. This is
>> especially true for “to-many” relationships.
>>
>> You can “flip” the “exists” sql into an “in” with an additional boolean
>> parameter. Play with the true-false value of “useInClauseInstead” to tune
>> performance. If you want to learn more then watch the slides here:
>> http://www.chatnbike.com/presentation_existsQualifier/
>>
>> You’ll be able to lick this, don’t worry. Dig in :-)
>>
>> Cheers,
>> AARON ROSENZWEIG / Chat 'n Bike
>> e: [email protected] t: (301) 956-2319
>>
>>
>> On Apr 14, 2014, at 4:49 PM, Kevin Hinkson <[email protected]> wrote:
>>
>>> Hello,
>>>
>>> I was hoping someone would be able to point me in the direction of how to
>>> handle generating a to many qualifier that involves a key path (not just a
>>> single key).
>>>
>>> A code example:
>>>
>>> // Generates a qualifier for the Profile for this account and the Profiles
>>> of any account on the same team (or that is the intention)
>>> public static EOQualifier visibleToAccountQualifier(Account account)
>>> {
>>> EOQualifier profilesDirectlyTiedToAccount =
>>> Profile.ACCOUNT.eq(account);
>>> String teamProfilesKeyPath = ERXQ.keyPath(Profile.ACCOUNT_KEY,
>>> Account.TEAMS_KEY, Team.ACCOUNTS_KEY);
>>> EOQualifier teamProfilesQualifier = ERXQ.has(teamProfilesKeyPath,
>>> new NSArray<Account>(account));
>>> return ERXQ.or(profilesDirectlyTiedToAccount, teamProfilesQualifier);
>>> }
>>>
>>> Performing a fetch with this qualifier generates the following error.
>>>
>>> EvaluateExpression failed:
>>> <com.webobjects.jdbcadaptor.PostgresqlExpression: "SELECT DISTINCT t0.id
>>> FROM Profile t0 INNER JOIN Account T1 ON t0.accountID = T1.id INNER JOIN
>>> AccountTeam T2 ON T1.id = T2.accountId INNER JOIN Team T3 ON T2.teamId =
>>> T3.id INNER JOIN AccountTeam T4 ON T3.id = T4.teamId WHERE (T4.teamId IN (
>>> SELECT Team.id FROM Team,AccountTeam null WHERE Team.id=T4.teamId AND
>>> null.accountId IN (1) GROUP BY Team.id HAVING COUNT(*)=1 ) OR t0.accountID
>>> = ?::int8)" withBindings: 1:1(accountID)>:
>>> Next exception:SQL State:42601 -- error code: 0 -- msg: ERROR: syntax
>>> error at or near "null"
>>> Position: 281.
>>>
>>> There is a null in there where there shouldn't be one (on the inner
>>> select). Am I using this qualifier incorrectly or is this indicative of a
>>> modelling error or even a bug? If it helps, I'm using PostgreSQL.
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