Nick Johnson's newsgroup e-mail explains pretty much what you need.. except
he leaves out some details (don't know, maybe he was busy building out the
Appengine subsystem at the time or something) explaining exactly how to set
it up underneath.
You should probably try something like this (which I believe is what Mr
Johnson's example uses underneath). I use Python so you're on your own with
Java, but the concept is identical (I'm doing this the lazy way so there is
no thought put to what property types should be used.):
class baseEmail(db.Model):
From = db.StringProperty()
To = db.StringProperty()
Subject = db.StringProperty()
Message = db.StringProperty()
TimeStamp = db.DateTimeProperty()
Attachment = db.BlobProperty()
class metaEmail(db.Model):
Status = db.StringProperty()
From = db.StringProperty(indexed=False)
Subject = db.TextProperty()
TimeStamp = db.DateTimeProperty()
I haven't bothered with thinking too deeply about the "right" ways to pick
property types.. or whether to mark some as indexed=False.. but this gets
the core concept.
For this example, baseEmail.key().name() == metaEmail.key().name() (but
they don't need to be in some child parent relationship or anything silly
like that.. you don't need transactions for this).
When a user clicks "Refresh" to see if they have more messages.. a process
runs that does something like this:
newEmails = db.baseEmail().all().filter('TimeStamp >',
MaxMetaEmailTimeStamp).fetch()
newMetaEmails = []
for email in newEmails:
metaEmail = metaEmail(key_name = email.key().name(), Status = 'Unread',
>From = email.From, Subject = email.Subject, TimeStamp = email.TimeStamp)
newMetaEmails.append(metaEmail)
db.put(newMetaEmails)
And, at the same time.. it displays the newMetaEmails on screen.
Now, there are more and more optimizations to add (you could use
ReferenceProperty with this if you want tighter associations).. but this is
the core idea..
You have metaEmail which is just metadata pointing to the underlying
baseEmail data.. make metaEmail as small as possible.. if you don't need
Subject or other stuff... leave those off.. the only properties you really
need are Unread and TimeStamp.
You can change the metaEmail.Status to 'Deleted' for deleted emails.. and
only truly delete them once every 24 hours or something.. this would allow
for a handy undelete option.. etc.
On Mon, Jan 10, 2011 at 1:27 AM, nischalshetty <nischalshett...@gmail.com>wrote:
> My bad. I forgot to mention, there would be an option where I show just the
> 'unread' tweets to the user or just the 'read' tweets. When I show all
> tweets, your example would work perfectly fine. But what about the other two
> scenarios? Any pointers would help. I use GAE/J.
>
> -N
>
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