Hi Dave,
It is a minor bug, but still a bug. When I have time I will give it a look.
I am working with the derived attributes with no major complaints now.
Still, there are some problems with EO and derived attributes.
1) I prefer to implement my business logic in my custom classes rather than
in SQL code that will often be hard to maintain and that will almost
certainly be tailored for a specific RDBMS. Anyway, what is the point in
having custom classes and the power of Enterprise Objects if I must rely on
custom-tailored SQL code?
So, I simply create a derived attribute and then I override it in my custom
class, and then forget the existence of the derived attribute. To make my
typing shorter I tried to include dummies for the SQL statement, as simple
as returning an empty string, ''. But EO did not interpret correctly my
reasoning and tried to use it with an error. I ended using a very stupid
dummy for all my derived attributes, since I want the model to be database
agnostic. I use if(TRUE,NULL,NULL) and then override the derived attributes
with my custom logic in my custom classes. I am currently not concerned
with database performance, I am just trying to develop a valid programming
technique for the context of D2W applications.
2) I implemented two derived classes, Person and Organization, since both
are a Party. The subclasses are differentiated by the type attribute. Up to
a point EO will deal with the Party entity very well, essentially when I
try to access only the attributes or derived attributes that are common to
both subclasses. When I needed the equivalent of this SQL statement
select distinct party.id, party.created, party.lastmodified,
if(party.status = 0,'Active','Inactive') as status, if(party.type = 0,
'Natural Person', 'Legal person') as type,
(
case party.type
when 0 then concat(person.firstName, ' ', person.lastName)
when 1 then organization.name
end
) as fullName from party inner join person, organization where
(party.personID = person.id or party.organizationID = organization.id);
EO returned an empty set, because it used party.personID = person.id AND
party.organizationID = organization.id instead of OR as my SQL statement.
Whenever I constructed a derived attribute with columns from both tables EO
generates the SQL inner join clause with an AND instead of an OR. I found
no way to solve this problem and that's one of the reasons I moved to dummy
derived attributes statements.
3) In simple listings for the base class, Party, EO will generate a very
similar SQL statement but will effectively lack the DISTINCT clause
doubling the result set. This happens for queries too. For the listings I
circumvented the problem by creating a allParties fetch specification in my
Party entity
type = 0 OR type = 1
and then implementing the list page this way
public WOComponent listPartyAction() {
ListPageInterface newListPage =
(ListPageInterface)D2W.factory().pageForConfigurationNamed("List" + Party.
ENTITY_NAME, session());
EODataSource ds =
newERXDatabaseDataSource(ERXEC.newEditingContext(), Party.
ENTITY_NAME, "allParties");
newListPage.setDataSource(ds);
return (WOComponent) newListPage;
}
This way my list page displays the correct set of EO objects. I still have
to work on the query issue with an adequate delegate implementing an
additional fetch specification, but I deferred the solution to a later
moment since it is already identified and easily implemented.
I am not sure if I am being naive or using EO in a very stupid way (or both
perhaps, since stupidity comes after naivety). I would appreciate any
sincere and frank comments and criticisms, since I am doing all this in a
huge effort to deepen my understanding of EO and Wonder and then become a
better WO developer, hoping to contribute to the community instead of only
asking silly questions.
Regards,
Angelo
2014-03-24 10:12 GMT-03:00 David Avendasora <webobje...@avendasora.com>:
> Hi Angelo,
>
> The question is, why does EO expect a column for a derived attribute for a
>> custom class and not for a ERXGenericRecord?
>>
>>
>
> It doesn't. You've found a EntityModeler bug I just found last week as
> well. A derived attribute should not have a value for "columnName" in the
> .plist - regardless if it has a specific custom/generic class or not. It
> should either be an empty string (columnName = "";) or just remove the
> entry all together.
>
> I don't think EOF will even look at the definition entry if there is a
> value for columnName.
>
> Your entry of:
>
> definition = "case code when 0 then 'Active' when 1 then 'Inactive' end";
>>
>>
> Should work correctly if that would be a valid SQL clause in a MySQL
> select statement.
>
> I think if you just get rid of the columnName entry it should work.
>
> Dave
>
>
>
> On Mar 23, 2014, at 1:50 PM, Ângelo Andrade Cirino <aacir...@gmail.com>
> wrote:
>
> Hi Aaron,
>
> 1) You are right, I am using Eclipse and WOlips, so, forgive me for the
> old times lingo, but I am really using Eclipse's (WOlips) Entity Modeler.
>
> 2) Since I am dedicating some time to deepen my understanding of Wonder I
> decided to do it with a new Eclipse (Kepler) install. I am using Kepler and
> the latest WOlips 4.3 stable build. After finishing installation I just
> forgot to turn off generate bundles...
>
> 3) Unfortunately we need to live with the Eclipse problems. But Apple's PB
> and EOModeler weren't free of problems too...
>
> Angelo
>
>
> 2014-03-23 14:32 GMT-03:00 Aaron Rosenzweig <aa...@chatnbike.com>:
>
>> Hi Angelo,
>>
>> Glad you got it working in the end. A couple things though:
>>
>> 1) You keep saying "EOModeler." Technically that is an Apple product that
>> requires the Objective-C to Java bridge which has not worked since probably
>> Mac OS X Tiger. Is that what you are using or are you using "EntityModeler"
>> that runs in Eclipse?
>>
>> 2) Are you using the "bundle-less build" in Eclipse? If you are not, some
>> of these problems could be related to that. Since it has been possible to
>> run without generating a bundle, I doubt anyone has tested the older way
>> much.
>>
>> 3) Eclipse just sucks... in general. I mean, it's a tall order, taking all
>> those "dead" files on disk and then puffing them up like the "living dead"
>> in a cool IDE so that you can see "who calls who" and "refactor" etc. But
>> It's easy to get out of sync or just to have problems. If you are running
>> EntityModeler on its own (Can you do that? I know RuleModeler can... I'm not
>> sure about EntityModeler) then you better "refresh" all your projects and
>> "clean" all your projects after you make an edit and save from
>> EntityModeler. It's what I have to do when using any external tool. And
>> sometimes, even when I'm totally in the Eclipse universe something
>> invariably will screw the pooch and I need to "refresh" "clean all" and
>> sometimes restart Eclipse. I call it the "Eclipse dance."
>> *AARON ROSENZWEIG* / Chat 'n Bike <http://www.chatnbike.com/>
>>
>> *e:* aa...@chatnbike.com *t:* (301) 956-2319
>> [image: Chat 'n Bike][image: Chat 'n Bike]
>>
>> On Mar 23, 2014, at 11:58 AM, Ângelo Andrade Cirino <aacir...@gmail.com>
>> wrote:
>>
>> Hi Aaron,
>>
>> Thank you for your prompt answer. Unfortunately none of the suggestions
>> worked.
>>
>> 1) I can't find any combination of double or single apostrophe that will
>> work. A similar MySQL SELECT statement is as simple as this
>>
>> select Party.id as partyID, (case status
>> when 0 then 'Active'
>> when 1 then 'Inactive'
>> end) as fullStatus from Party;
>>
>> Even this simple derived attribute that returns a constant won't work
>> (from the plist entity file):
>>
>> {
>> columnName = fullStatus;
>> definition = "'Full Status'";
>> name = fullStatus;
>> prototypeName = varchar16;
>> },
>>
>> with the following error:
>>
>> IllegalStateException: sqlStringForAttribute: attempt to generate SQL
>> for attribute 'fullStatus' on entity 'Party' with undefined column name.
>> You must define a column name for this attribute before attempting a
>> database operation.
>>
>> 2) The read format option didn't work either since the attribute is an
>> integer number and the return value is a string. I attempted this format:
>>
>> if(%P,'Active','Inactive')
>>
>> and it resulted in this error:
>>
>> JDBCAdaptorException: Invalid value for getInt() - 'Inactive'
>>
>> However, this works just fine as a read format:
>>
>> if(%P,2*%P,5*%P)
>>
>> But I am stubborn and think that a derived attribute is a desirable
>> attribute. I would like to use it for more complex operations, for example
>> involving concatenation of strings in related entities.
>>
>> Anyway, trying to figure out what is happening, it occurred to me that my
>> Party entity is a custom class, so I tried a non-custom class with a simple
>> entity to see if the derived attribute would work. And it worked. My simple
>> tentative entity is this:
>>
>> {
>> attributes = (
>> {columnName = code; name = code; prototypeName = intNumber; },
>> {
>> columnName = fullStatus;
>> definition = "case code when 0 then 'Active' when 1 then
>> 'Inactive' end";
>> isReadOnly = Y;
>> name = fullStatus;
>> prototypeName = varchar16;
>> userInfo = {"_EntityModeler" = {generateSource = NO; }; };
>> },
>> {allowsNull = N; name = id; prototypeName = id; }
>> );
>> attributesUsedForLocking = (code, id);
>> className = "er.extensions.eof.ERXGenericRecord";
>> classProperties = (code, fullStatus);
>> externalName = Status;
>> fetchSpecificationDictionary = {};
>> name = Status;
>> primaryKeyAttributes = (id);
>> }
>>
>> But this isn't a solution for me, since my entity will have a lot of
>> business logic that demands a custom class. Perhaps I should set my Party
>> entity as a ERXGenericRecord and then subclass it to implement the business
>> logic.
>>
>> The question is, why does EO expect a column for a derived attribute for
>> a custom class and not for a ERXGenericRecord?
>>
>> By the way, the original Apple EOModeler User Guide doesn't state that a
>> derived attribute will not work for a custom class nor does the
>> documentation states that a derived attribute should be modeled for a
>> generic record.
>>
>> Angelo
>>
>> 2014-03-23 1:01 GMT-03:00 Aaron Rosenzweig <aa...@chatnbike.com>:
>>
>>> Hi Angelo,
>>>
>>> Couple things to try:
>>>
>>> 1) Remove the single apostrophes surrounding "status" and try again. It
>>> is possible that it isn't parsing properly... don't column names need to
>>> have
>>> "double apostrophes" ??? Perhaps MySQL is lax about that but still... Either
>>> use no apostrophe or use a "double apostrophe" meaning a single character
>>> the shift-apostrophe key. If it is a single apostrophe that is a String in
>>> SQL.
>>>
>>> 2) Try a different way. Remove all the code you have in the derived part
>>> and make this a normal EOAttribute. Put "STATUS" in there by itself. Now go
>>> to the "advanced" tab and type what you want in the "Read Format" and check
>>> the "read only" box. In the read format you want to use %P for your
>>> columnName so you'll want something like this:
>>>
>>> case %P when 0 then 'Active' when 1 then 'Inactive' end
>>>
>>> Honestly, I almost always use the #2 way and never the "derived" way
>>> because it is more flexible. I like the idea that I define the column in
>>> one box and in another I write something complex but refer to it with %P.
>>>
>>> Try it out and report back.
>>> *AARON ROSENZWEIG* / Chat 'n Bike <http://www.chatnbike.com/>
>>>
>>> *e:* aa...@chatnbike.com *t:* (301) 956-2319
>>>
>>>
>>>
>>
>>
>
>
> --
> Ângelo Andrade Cirino
> aacir...@gmail.com
> 31-3494-8642
> 31-9303-0695
> MSN aacir...@hotmail.com
> Skype aacirino
> _______________________________________________
> Do not post admin requests to the list. They will be ignored.
> Webobjects-dev mailing list (Webobjects-dev@lists.apple.com)
> Help/Unsubscribe/Update your Subscription:
>
> https://lists.apple.com/mailman/options/webobjects-dev/webobjects%40avendasora.com
>
> This email sent to webobje...@avendasora.com
>
>
>
> ----------------------------------------------------------
> *WebObjects** - so easy that even Dave Avendasora can do it!(tm)*
> ----------------------------------------------------------
> *David Avendasora*
> Senior Software Abuser
> Nekesto, Inc.
>
>
>
>
>
>
--
Ângelo Andrade Cirino
aacir...@gmail.com
31-3494-8642
31-9303-0695
MSN aacir...@hotmail.com
Skype aacirino
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Webobjects-dev mailing list (Webobjects-dev@lists.apple.com)
Help/Unsubscribe/Update your Subscription:
https://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com
This email sent to arch...@mail-archive.com
