App Engine uses "soft schemas" for its entities. That is, if you still need to read from a property but no longer need to write from it, simply leave the property field in your entity. You won't be able to display the property if you remove it from your entity, but you can build your application such that it does not accept new writes to the property.
Here's a pretty good session from Google I/O 2009 that discusses this: http://code.google.com/events/io/2009/sessions/SofterSideofSchemas.html On Mon, Nov 23, 2009 at 7:34 PM, sea <ok_...@163.com> wrote: > Hi > > Environment :GAE for java, JPA > > I defined a java object(POJO) and stored some data in it. But later I > found a property of that java object(POJO) was useless, > and there was no data in that property.So I removed that property, but > that caused a big problem, the data in that > java object(POJO) can not be displayed by program. > > So could you tell me how to deal with it? I want to remove the useless > property of java object(POJO) , and want original data can be > displayed by program. > > Thanks a lot. > > -- > > You received this message because you are subscribed to the Google Groups > "Google App Engine" group. > To post to this group, send email to google-appeng...@googlegroups.com. > To unsubscribe from this group, send email to > google-appengine+unsubscr...@googlegroups.com<google-appengine%2bunsubscr...@googlegroups.com> > . > For more options, visit this group at > http://groups.google.com/group/google-appengine?hl=en. > > > -- Ikai Lan Developer Programs Engineer, Google App Engine -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to google-appeng...@googlegroups.com. To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en.
