EclipseLink defers write operations by default. All necessary DML
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> Today's Topics:
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> 1. Re: Query using WHERE - IN on a Join Table Question (sonavor)
> 2. Re: Re: one connection for each request (Yannick Majoros)
> 3. Re: Re: one connection for each request
> (
Christopher.Mathrusse@...)
> 4. MySQL batch delete bug (211084) - why so low priority?
> (Tobias Marklund)
> 5. Expression for all lineitems that where picked today
> (Philipp Kursawe)
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> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 26 Jun 2009 12:53:24 -0700 (PDT)
> From: sonavor <
jw@...>
> Subject: Re: [eclipselink-users] Query using WHERE - IN on a Join
> Table Question
> To:
eclipselink-users@...
> Message-ID: <
24226373.post@...>
> Content-Type: text/plain; charset=us-ascii
>
>
> Thanks for the information Chris.
>
> I did try a few tests with the EclipseLink ExpressionBuilder. I was able to
> get that to work with a ReadAllQuery but I still had to build the expression
> where I am do "OR" operations between the conditions -
>
> Expression exp = null;
> ExpressionBuilder eb = new ExpressionBuilder(TestListing.class);
> for ( Iterator it=kwList.iterator();it.hasNext(); ) {
> TestKeywords tkw = (TestKeywords)it.next();
> Expression expKw =
> eb.anyOf("testKeywordsCollection").equal(tkw);
> if ( exp == null ) {
> exp = expKw;
> } else {
> exp = exp.or(expKw);
> }
> }
>
> ReadAllQuery readAllQuery = new ReadAllQuery(TestListing.class);
> readAllQuery.setSelectionCriteria(exp);
>
> ...then get the ActiveSession from the EntityManager and run the query...
>
> I think I will go with the EntityManager.createQuery where I build up the
> "OR" operator on the submitted keyword Id values for now.
>
> When EclipseLink 2.0 is available I will retry the "IN" operation. I don't
> see a download for EclipseLink 2.0 on the web site.
>
>
>
> Christopher Delahunt wrote:
>
>> Hello,
>>
>> IN is supported, but in JPA 1.0, IN cannot take a collection as a
>> parameter which is why you get an exception.
>>
>> EclipseLink native expressions have always allowed taking a collection
>> as a parameter if you are able to build your query that way instead, or
>> if you can upgrade, support was just added to EclipseLink 2.0 so that
>> JPQL will also allow taking the collection and is in the more recent
>> nightly builds (added 2009-06-10 through bug 249224)..
>>
>> Best Regards,
>> Chris
>>
>> sonavor wrote:
>>
>>> I am using Eclipselink and have three tables I am testing. I am
>>> experimenting with have a many-to-many relationship between a main,
>>> listing
>>> table and a keyword table.
>>> The database is MySql.
>>>
>>> One table is called TEST_LISTING with these columns -
>>> LISTING_ID integer (PK)
>>> LISTING_NAME varchar(40)
>>>
>>> Second table is called TEST_KEYWORDS with these columns -
>>> KW_ID integer (PK)
>>> KW_NAME varchar(24)
>>>
>>> Third table is a join table called KW_MAP with these columns -
>>> LISTING_ID integer (PK)
>>> KW_ID integer (PK)
>>>
>>> So, using Netbeans 6.1, I generated two JPA entity classes -
>>> TestListing.java
>>> TestKeywords.java
>>>
>>> that have a many-to-many relationship to each other via the KW_MAP table.
>>>
>>> This all works and I can use a join query like this -
>>>
>>> My method receives an ArrayList of Integer values that are the Id of
>>> selected TEST_KEYWORDS called tkwIdArray.
>>>
>>> StringBuffer qSB = new StringBuffer();
>>> qSB.append("SELECT t FROM TestListing as t ");
>>> qSB.append("JOIN t.testKeywordsCollection as tkw ");
>>> qSB.append("WHERE ");
>>>
>>> for ( int i=0;i<tkwIdArray.length;i++ ) {
>>> Integer tkid = tkwIdArray[i];
>>> if ( i == 0 ) {
>>> qSB.append("tkw.kwId =
>>> :arg").append(String.valueOf(i)).append(" ");
>>> } else {
>>> qSB.append("OR tkw.kwId =
>>> :arg").append(String.valueOf(i)).append(" ");
>>> }
>>> }
>>>
>>> Query q = em.createQuery(qSB.toString());
>>> for ( int i=0;i<tkwIdArray.length;i++ ) {
>>> q.setParameter("arg"+String.valueOf(i), tkwIdArray[i]);
>>> }
>>>
>>> List<TestListing> tList = q.getResultList();
>>>
>>> Although that works I would like to create the query where it looks more
>>> simple by using "IN"
>>>
>>> I tried this -
>>>
>>> I create a List<Integer> named "idList" that is an ArrayList of the
>>> submitted TEST_KEYWORDS Id values.
>>>
>>> List<TestListing> tList = em.createQuery("SELECT t FROM TestListing as t
>>> JOIN t.testKeywordsCollection as tkw WHERE tkw.kwId IN (?1)")
>>> .setParameter(1,
>>> idList).getResultList();
>>>
>>> When I try this query I get -
>>>
>>> java.lang.IllegalArgumentException: You have attempted to set a value of
>>> type class java.util.ArrayList for parameter 1 with expected type of
>>> class
>>> java.lang.Integer from query string SELECT t FROM TestListing as t JOIN
>>> t.testKeywordsCollection as tkw WHERE tkw.kwId IN (?1).
>>>
>>> Does Eclipselink not support using the "IN" attribute in a query?
>>>
>>> As a different kind of test I rewrote the join query to find TEST_LISTING
>>> records by joining on the TEST_KEYWORDS.KW_NAME column so I could try the
>>> "IN" with a String Array. I can get the "IN" to work with a hard-coded
>>> String array like -
>>>
>>> List<TestListing> tList = em.createQuery("SELECT t FROM TestListing as t
>>> JOIN t.testKeywordsCollection as tkw WHERE tkw.kwName IN
>>> ('italian','food')").getResultList();
>>>
>>> but when I change it to this -
>>>
>>> List<String> kwnList = new ArrayList<String>();
>>> kwnList.add("italian");
>>> kwnList.add("food");
>>> List<TestListing> tList = em.createQuery("SELECT t FROM
>>> TestListing
>>> as t JOIN t.testKeywordsCollection as tkw WHERE tkw.kwName IN (?1)")
>>> .setParameter(1, kwnList).getResultList();
>>>
>>> I get the error -
>>> java.lang.IllegalArgumentException: You have attempted to set a value of
>>> type class java.util.ArrayList for parameter 1 with expected type of
>>> class
>>> java.lang.String from query string SELECT t FROM TestListing as t JOIN
>>> t.testKeywordsCollection as tkw WHERE tkw.kwName IN (?1)
>>>
>>> Is there a way to do this using Eclipselink or should I just stick with
>>> my
>>> iteration construction of the query using "OR" clauses?
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
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Re: one connection for each request