Re: Flattening attributes
Re: Flattening attributes
- Subject: Re: Flattening attributes
- From: Rico Landefeld <email@hidden>
- Date: Fri, 17 Feb 2006 09:33:20 +0100
Ian Joyner schrieb:
Just hit this same problem with flattened attributes myself. When
inserting, it wanted to insert the target record of the flattening as
well. I only wanted the flattened attribute to retrieve the attribute
from the target record, so I just included it as a routine in the
source class:
public String operation_name () {
return operation ().operation_name ();
}
You might find this solves some ills.
this is a nice solution if you use custom objects. but in my app we use
the input data for analysis purposes only, there is no business logic.
so i use generic records.
rico
On 16/02/2006, at 8:20 PM, Rico Landefeld wrote:
Ian Joyner schrieb:
The problem I have found with flattened attributes is that they
seem to work fine for one thing but not for another. You have to
test them out on all four CRED operators (create, read, edit,
delete). Often I find that EO generates strange errors about inv
paths not being found when deleting, etc. I have tried them out in
order to perform joins to make access more efficient, but usually
some other problem turns up. Perhaps I'm just not proficient at
them yet.
Your design also seems a little restrictive, large companies can
have multiple addresses, so shouldn't you make this a to-many
relationship – in that case flattened attributes will not be
possible and will just make your design less flexible for future
'feature requests'.
hi ian, there is not need for to many relationships at this point. my
dbcontext delegate seems to work. but its really hacking. i think the
flattening feature is meaningful for my use case. but it doesn't work
correctly. for more details look at my email to ken.
regards,
rico
On 15/02/2006, at 10:11 PM, Rico Landefeld wrote:
hi all,
i have the following problem with flattening. i have an address
entity in
my eomodel wich is used by many other entities like company.
company has a
to-one relationship to address. i like to flatten some of the address
attributes into company (address is a weak entitytype). if i insert an
company without filling the address fields there is no insert into the
address table. when some address fields are filled, eof generates an
insert for address but without an primary key and the address
relationship
of the company object is empty! i have written an big
EODatabaseContext.Delegate to handle this. is there a better solution?
Whoa, that definitely seems like a bad idea, but maybe those who
are further down the track than I could advise (who said "if you
are writing code in EO, you are doing it wrong"). Have you tried
'Owns destination' and 'Propagate primary key' in the advanced
relationship pane in EOModeler. But be careful, you have to
understand the semantics of these exactly.
Ian
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Rico Landefeld
Takwa GmbH
Softwareentwickler
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Fax.: +49 361 6534097
eMail: email@hidden <mailto:email@hidden>
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