Re: efficient copy?
Re: efficient copy?
- Subject: Re: efficient copy?
- From: Ken Anderson <email@hidden>
- Date: Sun, 01 Mar 2015 13:36:34 -0500
How often does this have to happen? Does it need to happen while other operations are going on that might interfere?
My basic approach is KISS unless there’s a reason to do it otherwise, so I would just do a long response page that does this with EOs, and maybe multiple EC’s in a loop to keep memory usage low.
> On Mar 1, 2015, at 10:51 AM, OC <email@hidden> wrote:
>
> Hello there,
>
> I'll need to copy thousands of objects from one table to another; the copying'll be almost verbatim, but for a relationship. Namely,
>
> entity OldAuction <->> OldRecord (relationships records->> and inverse <-auction)
> entity NewAuction <->> NewRecord (relationships records->> and inverse <-newAuction)
>
> Entity NewRecord has all attributes of OldRecord (and perhaps a couple of others)
>
> The naïve code would be something like
>
> ===
> def orig=... an object of the OldAuction entity ...
> def new=... an object of the NewAuction entity ...
> orig.allRecords().each { OldRecord old ->
> def newRecord=EOUtilities.createAndInsertInstance(new.editingContext(),'NewRecord')
> newRecord.newAuction=new
> newRecord.takeValuesFromDictionary(old.valuesForKeys(old.attributeKeys()))
> }
> new.editingContext().saveChanges()
> ===
>
> There's no need to make this lightning fast, e.g., a dedicated SQL procedure would definitely be an overkill; but still, it should be as fast as possible without making the code too complex, unintelligible and unmaintainable. I wonder, what's the best way? Guess I might e.g., fetch rawrows for orig.allRecords somehow, and use _them_ for the takeValuesFromDictionary argument?
>
> Thanks,
> OC
>
>
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