Good point. I think we can and should support listproperty. I also
think its behavior can be mimicked in relational databases. This will
probably happen within 1-2 weeks.
Massimo
On May 24, 12:50 am, Cory Preus <c...@voxmanus.com> wrote:
> > Can you make a concrete example? It will help us improve.
>
> The oft-cited ListProperty is a great example. Because GAE/BigTable
> doesn't provide substr support, we have a couple options for a search
> facility. One is to take a string, say "foobar" and tokenize it into
> parts.
>
> ['fo','oo','ba','ar','foo','bar','foob','obar','fooba','oobar','foobar']
>
> Using ListProperty, this would be a single write. Our BigTable model
> looks as such:
>
> id name tokens
> 1 foobar ['fo','oo','ob','ba','ar','foo','bar',...]
>
> And a search query:
>
> # Get all entities where numbers contains a 6.
> results = db.GqlQuery("SELECT * FROM MyModel WHERE tokens = 'foo'")
>
> GQL natively returns all entities contain an element in a list.
>
> http://code.google.com/appengine/docs/python/datastore/entitiesandmod...
>
> Conversely, using the oft cited IS_IN_DB pattern for web2py, we would
> have 12 rows inserted, one for each token with a column of comma
> delimited foreign key ids to each full-string entity matching the
> token and a bunch of code to manage the integrity across tokens/
> entities instead of what is relevant in this case: tokens *per*
> entity. Duplication of a token is irrelevant.
>
> So in this scenario, which is key for the project I'm working on with
> a friend, a single SELECT using GAE's API would produce the results
> needed versus a series of queries to a) SELECT the token in a tokens
> table, then iterate over the elements execute SELECTs on each to get
> the representation.
>
> While the ListProperty may be unique to GAE/BigTable, omitting it
> removes the ability to harness GAE's power. It is also representative
> of the difference between data store paradigms, I think.
>
> Hope this helps.
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