Re: Multiple clients in single DB
Re: Multiple clients in single DB
- Subject: Re: Multiple clients in single DB
- From: Patrick Middleton <email@hidden>
- Date: Thu, 26 Apr 2007 09:46:19 +0100
On 26 Apr 2007, at 02:33, Dave Elsner wrote:
Hi,
I have an WO5.3 application I want to deploy to five different
clients, all have the same DB (Oracle) schema but different data. I
would like to use a shared database with a new column in each table
"client" that has the client ID. Then override awakeFromInsertion
for all EOEntities to set the client ID and also add to the
Application constructor a loop that sets an EOQualifier on each
entity in the model limiting objects to the current client.
Questions:
* Is this the correct approach to solve this problem? (i.e not
wanting to update X number of identical DB schemas every-time a
change is made, keeping the data in the one location for reporting)
* I tried EOEntity.setRestrictingQualifier but that overrides
any single table inheritance setup in the model. Is there away to
merge two EOQualifiers?
Cheers
Dave
My solution to this was to add a new entity Client, and make this
reachable from at least one other entity bearing useful data in your
schema. Via keypaths and joins, this entity should then now
reachable from any entity other interesting entity. You then use
EOEditingContext delegate API http://developer.apple.com/
documentation/WebObjects/Reference/API/com/webobjects/eocontrol/
EOEditingContext.Delegate.html#editingContextShouldFetchObjects
(com.webobjects.eocontrol.EOEditingContext,%
20com.webobjects.eocontrol.EOFetchSpecification to examine the
EOEntity for any fetch about to be carried out and to selectively
amend the fetch specification's quailfier to add another
EOKeyValueQualifier to achieve the required restriction. If your
code carries out custom fetches which need to bypass this restriction
mechanism, pass yourself a flag in the EOFetchSpecification's
userInfo dictionary.
This has worked very well for me in a number of apps since 1999, you
don't need to tinker with EOF (everything is as per the EOModel) and
all the required client ID stuff resides in a single table.
--
Patrick Middleton
OneStep Solutions plc
351 London Road Phone: +44 (0)1702 426400
Hadleigh Fax: +44 (0)1702 556855
Essex. SS7 2BT Email: email@hidden
England (MIME welcome)
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