With the low-level API, you would just set the Key of the old object to the
one one and persist it. With managed persistence via PersistenceManager or
EntityManager, I believe you can set a key and merge (but I'm not sure off
the top of my head).

On Wed, Sep 8, 2010 at 12:43 PM, Shaun <[email protected]> wrote:

> This might be very obvious, but imagine you have an object in the
> datastore that you simply want to to replace with another, i.e. keep
> the same key, just replace all the field values. Is there any easy way
> to do this without setting each field value of the datastore object
> with field values of the other object?
>
> As an example I find myself doing this alot:
>
> ExpenseEntry lJsonExpenseEntry = gson.fromJson(pExpenseEntryJson,
> ExpenseEntry.class);
>                ExpenseEntry lExpenseEntry =
> pm.getObjectById(ExpenseEntry.class,
> expenseKey);
>
>
> lExpenseEntry.setExpenseamount(lJsonExpenseEntry.getExpenseamount());
>
> lExpenseEntry.setExpensecategory(lJsonExpenseEntry.getExpensecategory());
>
>  lExpenseEntry.setExpensedate(lJsonExpenseEntry.getExpensedate());
>
>  lExpenseEntry.setExpensename(lJsonExpenseEntry.getExpensename());
>
>  lExpenseEntry.setExpensenotes(lJsonExpenseEntry.getExpensenotes());
>
>  lExpenseEntry.setExpenseuser(lJsonExpenseEntry.getExpenseuser());
>
>  lExpenseEntry.setProjectid(lJsonExpenseEntry.getProjectid());
>
> in order to update the datastore object, ideally I could do this all
> in a few lines by simply replacing the current datastore object with
> the new one. Maybe just removepersistence and then add it again?
> Thanks for the thoughts.
>
> Shaun
>
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-- 
Ikai Lan
Developer Programs Engineer, Google App Engine
Blog: http://googleappengine.blogspot.com
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