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
>
>
_______________________________________________
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
