tagresults = models.Tag.all().order(sort_order).filter("name
=",tag_name).fetch(10)
article_keys = [Tag.article.get_value_for_datastore(f) for f in tagresults]
results = db.get(seed_keys)
This will not result in a datastore fetch for each article key you
need. The ReferenceProperty already contains the full Article db.Key.
But why don't you put the tag words in a StringListProperty in the
Article object?
2010/6/1 Ben <magnetbo...@gmail.com>:
> My models look like this:
>
> class Article(db.Model):
> author = db.UserProperty()
> content = db.StringProperty(multiline=True)
>
> class Tag(polymodel.PolyModel):
> article = db.ReferenceProperty(Article)
> name = db.StringProperty()
>
> Now if I want to create a page which lists all the articles that use a
> particular tag, I'm doing this:
>
> tagresults = models.Tag.all().order(sort_order).filter("name =
> ",tag_name).fetch(10)
> article_keys = [f.article.key() for f in tagresults]
> results = models.Article.get(seed_keys)
>
> Could I be doing that better? Is that the proper way to store things
> as a reference, particularly if I want it to be a very fast query, and
> preferably saveable in memcache?
>
> Now I also want to do the reverse: create a page that lists articles
> in order, and shows every tag used for each article.
>
> articles = models.Article.all().order(sort_order).fetch(10)
> for article in articles:
> tags = [t for t in article.tag_set]
> article.tags = [t.name for t in tags]
>
> That's all I'm doing, and it thus its having to run a query to fetch
> the tags, I think.
>
> I think I'm possibly doing both of these wrong, because I want to
> prefetch and memcache the parent or child depending on which type of
> page (tag pages which show articles, and article pages which show
> tags). I've read about a dozen articles on using the
> get_value_for_datastore but it doesn't look like it does what I'm
> looking for, unless I'm just not understanding it...
>
> Any help?
>
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