Re: [Wonder-disc] ERMigration, DefaultValues and mySQL

[Johann W. <we...@is...>]

Am 04.08.2008 um 18:12 schrieb Mike Schrag:

>> just thinking aloud, what about adding the possibility to specify a
>> defaultValue in Entity Modeler?
> The ERXDefaultValues is already supported for normal EOF usage ...
> Migrations are kind of a weird special case, though.  Normal default
> values are often based on runtime values, but the only reason
> migration default values exist is to be able to add a new not-null
> column to backfill existing values.  It's not something you really
> want on the model because it's often a "fake" value that's very
> transient.  For "real" default values, I would use ERXDefaultValues
> (see ERXEntityClassDescription).

Interesting, did not know of ERXDefaultValues :-) But... these reside  
only in the model, do they? By using the method of ERXMigration the  
default value is set at the database level (with the SQL command ...  
DEFAULT defaultValue) so if I have any non-WO programs that are  
accessing the database (and writing to it) they will get these  
defaults too.
That leads me to the question, if I set the default value with  
ERXMigration and then create a new object in WO then this time WO will  
know nothing of that default value as long as it is set to a specific  
value or the object is refreshed?

jw

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