Re: Antw: Re: Migrating Data from a temporary table into another editingcontext
Re: Antw: Re: Migrating Data from a temporary table into another editingcontext
- Subject: Re: Antw: Re: Migrating Data from a temporary table into another editingcontext
- From: Chuck Hill <email@hidden>
- Date: Fri, 1 May 2009 07:50:35 -0700
On May 1, 2009, at 5:07 AM, Andri vonAllmen wrote:
Hi Chuck,
thanks for your response.
I can't fetch inside the thread because the thread did not insert
the data into the temporary table
Change it so that it does. Move the code.
and can't access them at all. But the session should be able to
transfer these data to the thread somehow.
Try fetching this temp data as raw rows instead of EOs. Or do you
need the Java classes.
I also tried to invoke all getter methods of the objects in the
session for getting the attribute (and relationship) values in order
to set them to a newly created object (using reflection) by using
the respective setter methods, but, with the same results....the
getter methods already return null values (but they don't if I'm
doing the same with some data from a "permanent" table).
Using the mentioned copy code from Practical WebObjects didn't help
too.
I can't figure out whats going wrong. Hard copying, refetching,
refreshing, faulting, everything i do, lets the objects forget about
their attributes values...
There is something going on that you are not telling us.
Chuck
>>> Chuck Hill <email@hidden> Mittwoch, 29. April 2009
19:09 >>>
Hi Andri,
On Apr 29, 2009, at 5:19 AM, Andri vonAllmen wrote:
> 'loha folks,
>
> short: How do i migrate data, fetched from a temporary table, from
> one editing context into another?
>
> Details below...
>
> The situation is as follows:
>
> First, data are inserted into a temporary table (Oracle 8i) by using
> a stored procedure. Then, in the same procedure, these data are
> fetched from the temporary table into the user sessions editing
> context.
>
> Up to now, I've used ReportMill for generating reports based on this
> temporary data. This happens in the same editing context and does
> not cause any problems.
>
> But since ReportMill isn't fun to work with at all, I've decided to
> implement my own web-based reporting tool. This one generates the
> report in its own thread and uses its own editing context (no shared
> editing context). It works by simply processing a object graph and
> invoking all methods (attributes, relationships) using reflection
> (java.lang.reflect) based on some root objects that have to be
> passed to the reporting tool.
>
> Since the data source is a temporary table in this case, the data
> objects can't be inserted into another editing context, because an
> exception, telling that these objects can't be registered in two
> editing contexts, would be (and is) shown.
It sounds to me like you were doing something wrong. Why not just
fetch the data into the thread's EC instead of the session's?
> So, I've tried to migrate them into a new editing context by
> faulting for the objects global id in the original editing context.
> This basically works, but the migrated data, namely all attribute
> values, relationships etc. are NULL.
I don't understand why that should be.
> For permanent tables, this way of migration works well (code below):
>
> EOEditingContext oldEditingContext =
> enterpriseObject.editingContext();
> EOGlobalID globalID =
> oldEditingContext.globalIDForObject(enterpriseObject);
> result = newEditingContext.faultForGlobalID(globalID,
> newEditingContext);
>
> Another trial was, to "copy" all objects, telling the old editing
> context to forget about them and inserting the copy into the new
> editing context (see code below).
>
> EOEnterpriseObject result = enterpriseObject;
> enterpriseObject.editingContext().forgetObject(enterpriseObject);
> newEditingContext.insertObject(result);
>
> But this does not work either. When trying to get some attributes
> value or another object reachable over a relationship, still null is
> returned.
Because you told it to forget the data!
> BUT, when adding e.g. a system out BEFORE migrating the data,
> accessing some value (e.g. the primary key), the migrated data are
> not null (in fact, now all attributes and relationships and so on
> are accessible and do return the correct value).
That is because it then faults in the data.
> Since I'm treating this phenomenon for hours and don't see the
> light, I finally have to ask for help. Any hints would be
appreciated.
I'd try and fetch directly into the thread's EC. Failing that,
Practical WebObjects has code to copy a graph of objects.
Chuck
--
Chuck Hill Senior Consultant / VP Development
Come to WOWODC'09 in San Fran this June!
http://www.wocommunity.org/wowodc09/
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--
Chuck Hill Senior Consultant / VP Development
Come to WOWODC'09 in San Fran this June!
http://www.wocommunity.org/wowodc09/
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