Hi All,
I would like to get your opinion on the best way to structure my
data model.
My app allows the users to filter the entities by four category types
(say A,B,C,D). Each category can have multiple values (for e.g.,
category type A can have values 1,2,3) but the
user can choose only one value per category for filtering. Please
note the values are unique across the category types as well. I could
create four fields corresponding to the four types but it does not
allow me to expand to more categories later easily. Right now, I just
use one list field to store the different values as it is easy to add
more category types later on.
My model (simplified) looks like this:
class Example(db.Model):
categ = db.StringListProperty()
keywords = db.StringListProperty()
The field keywords will have about 10-20 values for each entity. For
the above example, categ will have up to 4 values. Since I allow for
filtering on 4 category types, the index table gets large with
unnecessary values. The filtering logic looks like:
keyword = 'k' AND categ = '1' AND categ = '9' AND categ = '14' AND
categ = '99'
Since there are 4 values in the categ list property, there will be
4^4 rows created in the index table (most of them will never be hit
due to the uniqueness guaranteed by design). Multiply it by the number
of values in the keywords table, the index table gets large very
quickly.
I would like to avoid creating multiple fields if possible because
when I want to make the number of category types to six, I would have
to change the underlying model and all the filtering code. Any
suggestions on how to construct the model such that it will allow for
ease of expansion in category types yet still not create large index
tables? I know there is a Category Property but not sure if it really
provides any specific benefit here.
Thanks!
-e
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