Are you trying to optimise the database access (ie. minimize the
number of queries), or provide a nice dictionary-style API for your
Student objects? What do you mean when you say that looping over
student.subjects is quite heavy?
An association proxy can be used to get dict-style access to a relationship:
https://docs.sqlalchemy.org/en/13/orm/extensions/associationproxy.html#proxying-to-dictionary-based-collections
There are also a couple of examples in the SQLAlchemy docs that
provide a dictionary-style API:
https://docs.sqlalchemy.org/en/13/orm/examples.html#module-examples.dynamic_dict
https://docs.sqlalchemy.org/en/13/orm/examples.html#module-examples.vertical
Hope that helps,
Simon
On Thu, Jul 2, 2020 at 8:46 PM Justvuur <justv...@gmail.com> wrote:
>
> Hi there,
>
> I'm struggling to find an efficient way to get a two columned subset into
> dictionary form.
>
> I have an entity that has a subset of data. The subset is linked to the
> entity via Id. The order of the subset of data is defined in another table.
>
> Example:
> Student - Id, firstname, lastname
> Subjects - StudentId, SubjectCode, SubjectName
>
> At the moment I'm looping through the SqlAlchemy result of "student.subjects"
> in python and creating a dictionary from that. It's quite heavy, especially
> when there are 2000+ students with a potential of 100+ subjects each.
>
> For each student, how do I get the subjects as a dictionary for a student
> where the key is the SubjectCode and the value is the SubjectName?
> Better yet, how can I get a result set: Id, firstname, lastname SubjectCode
> x, SubjectCode y, etc etc (where the SubjectName becomes the value and the
> SubjectCode becomes the column)?
>
> Regards,
> Justin
>
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