I haven't looked at the source of hibernate (or read) to see what
exactly goes on, but the erratic behavior of load() is precisely the
same as this:
Listing listing = (Listing)session.createQuery("from Listing
where id=:id")
.setLong("id", Long.parseLong(sListingId)).uniqueResult();
I just replaced the load() call with this, so now the source is:
public class BinaryFileDispatcher implements Dispatcher {
private Session session;
public BinaryFileDispatcher(Session session) {
this.session = session;
}
public boolean dispatch(Request request, Response response)
throws IOException {
String sListingId = request.getParameter("limg");
if(sListingId== null)
return false;
System.out.println("BinaryFileDispatcher.dispatch() -- " +
sListingId);
Listing listing = (Listing)session.createQuery("from Listing
where id=:id")
.setLong("id", Long.parseLong(sListingId)).uniqueResult();
response.setHeader("Content-Type", "text/html");
String test = "<html><body><h1>" + listing.getTitle() +
"</h1></body></html>";
response.setContentLength(test.length());
PrintWriter writer = response.getPrintWriter("text/html");
writer.append(test).flush();
return true;
}
}
Quick summary of the behavior with the following urls:
1) request /LStAug/?limg=1
works
2) request /LStAug/?limg=1 (again)
works
3) request /LStAug/?limg=2
breaks
4) request /LStAug/?limg=1
breaks, where it worked before
(restart container)
1) request /LStAug/?limg=2
works
2) request /LStAug/?limg=1
breaks
3) request /LStAug/?limg=2
breaks
so strange.
Jonathan Barker wrote:
> I'm not sure why it WORKED.
>
> Session.load will try to create an instance of Listing, which it can't
> because it is abstract.
>
> On the other hand, if you do a query, then even though you ask for a
> Listing, Hibernate will look for any descendant of Listing.
>
> The actual object type returned will depend on the actual type for any
> instance found. You can then cast to Listing without a problem.
>
> Get rid of load().
>
> Jonathan
>
>
>> -----Original Message-----
>> From: Chris Lewis [mailto:[EMAIL PROTECTED]
>> Sent: Thursday, July 24, 2008 14:37
>> To: Tapestry users
>> Subject: Re: T5.0.14-SNAPSHOT: strange behavior Dispatcher when using a
>> Session
>>
>> Hi Jonathan,
>>
>> Here is my dispatcher. As you can see it's in a very early stage so it's
>> both small and messy. The query is being done via:
>> session.load(Listing.class, Long.parseLong(sListingId));
>>
>> It was being done via createQuery and uniqueResult, with the same results.
>>
>> public class BinaryFileDispatcher implements Dispatcher {
>>
>> private Session session;
>>
>> public BinaryFileDispatcher(Session session) {
>> this.session = session;
>> }
>>
>> public boolean dispatch(Request request, Response response)
>> throws IOException {
>>
>> String sListingId = request.getParameter("limg");
>> if(sListingId== null)
>> return false;
>>
>> System.out.println("BinaryFileDispatcher.dispatch() -- "
>> + sListingId);
>> Listing listing = (Listing)session.load(Listing.class,
>> Long.parseLong(sListingId));
>>
>> response.setHeader("Content-Type", "text/html");
>>
>> String test = "<html><body><h1>" + listing.getTitle() +
>> "</h1></body></html>";
>> response.setContentLength(test.length());
>> response.getPrintWriter("text/html").append(test).flush();
>> return true;
>> }
>>
>> }
>>
>>
>> Jonathan Barker wrote:
>>
>>> Post your query and load code.
>>>
>>>
>>>
>>>> -----Original Message-----
>>>> From: Chris Lewis [mailto:[EMAIL PROTECTED]
>>>> Sent: Thursday, July 24, 2008 13:16
>>>> To: Tapestry users
>>>> Subject: Re: T5.0.14-SNAPSHOT: strange behavior Dispatcher when using a
>>>> Session
>>>>
>>>> It can't be a data issue. The records are persisted via hibernate and
>>>> work consistently as expected in pages. Like I said, I query the same
>>>> table to which the abstract class is mapped in my index page with no
>>>> problem at all. I also said that it works in the dispatcher for the
>>>> first entity I query, but any subsequent query to a _different_ entity
>>>> throws that exception. The query is also just a read (select). Any
>>>>
>> other
>>
>>>> ideas?
>>>>
>>>> thanks
>>>>
>>>> Yunhua Sang wrote:
>>>>
>>>>
>>>>> It sounds more like a data issue, check your data in database
>>>>>
>> carefully.
>>
>>>>> Yunhua
>>>>>
>>>>> On Wed, Jul 23, 2008 at 11:18 PM, Chris Lewis
>>>>>
>>>>>
>>>> <[EMAIL PROTECTED]> wrote:
>>>>
>>>>
>>>>>> Hello,
>>>>>>
>>>>>> I have a dispatcher that uses a hibernate session. The dispatcher is
>>>>>> auto bound and receives the session in the constructor. I'm using
>>>>>> tapestry-hibernate so that session instance is a proxy that gets the
>>>>>> real session for the current thread (right?). Now in testing my
>>>>>> dispatcher, I give it a url like:
>>>>>>
>>>>>> /MyContext/?limg=2
>>>>>>
>>>>>> The dispatcher looks for "limg" and if found, queries the session
>>>>>> assuming that its value is the PK of a mapped entity. When I trigger
>>>>>>
>>>>>>
>>>> the
>>>>
>>>>
>>>>>> dispatcher for the first time it works fine. If I refresh the page,
>>>>>> fine. If I change the value to something else, say 3, then it breaks
>>>>>> with a org.hibernate.InstantiationException:
>>>>>>
>>>>>> Cannot instantiate abstract class or interface:
>>>>>>
>>>>>>
>>>> com.mypackage.data.Listing
>>>>
>>>>
>>>>>> If I change the value back to 2, the same thing happens! "Listing" is
>>>>>>
>>>>>>
>>>> an
>>>>
>>>>
>>>>>> abstract class mapped as a super class entity via:
>>>>>>
>>>>>> @Entity
>>>>>> @Inheritance(strategy = InheritanceType.JOINED)
>>>>>>
>>>>>> Any clue what's going on here? Two things are perplexing me:
>>>>>>
>>>>>> 1) Querying mapped super classes is legal, and I in fact the same
>>>>>>
>> thing
>>
>>>>>> on my Index page with no problem.
>>>>>> 2) The query works the first time, but as soon as the id changes it
>>>>>>
>> is
>>
>>>>>> forever broken until I restart the container.
>>>>>>
>>>>>> Thanks in advance!
>>>>>>
>>>>>> chris
>>>>>>
>>>>>> --
>>>>>> http://thegodcode.net
>>>>>>
>>>>>>
>>>>>> ---------------------------------------------------------------------
>>>>>> To unsubscribe, e-mail: [EMAIL PROTECTED]
>>>>>> For additional commands, e-mail: [EMAIL PROTECTED]
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>> ---------------------------------------------------------------------
>>>>> To unsubscribe, e-mail: [EMAIL PROTECTED]
>>>>> For additional commands, e-mail: [EMAIL PROTECTED]
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>> --
>>>> http://thegodcode.net
>>>>
>>>>
>>>
>>> ---------------------------------------------------------------------
>>> To unsubscribe, e-mail: [EMAIL PROTECTED]
>>> For additional commands, e-mail: [EMAIL PROTECTED]
>>>
>>>
>>>
>>>
>> --
>> http://thegodcode.net
>>
>
>
>
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>
>
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