On 03/01/2017 08:27 PM, GMS wrote:
I have the following class models:
| class DiagnosisDetail(Model):
__tablename__ = 'vw_svc_diagnosis'
diagnosis_id = Column(String(32), primary_key=True)
first_name = Column(String(255))
last_name = Column(String(255))
mrn = Column(String(255))
dx_code = Column(String(255))
dx_id = Column(String(255), ForeignKey('dx_group.dx_id'))
diagnosisgroup = relationship("DiagnosisGroup")
dx_code_type = Column(String(255))
dx_name = Column(String(255))
__mapper_args__ = {
"order_by":[mrn, dx_name]
}
class DiagnosisGroup(Model):
__tablename__ = 'diagnosis_group'
dx_id = Column(String(32), primary_key=True)
mrn = Column(String(255))
dx_code = Column(String(255))
dx_code_type = Column(String(255))
dx_name = Column(String(255))
diagnosis_datetime = Column(DateTime)
__mapper_args__ = {
"order_by":[mrn, dx_name]
}|
where the underlying tables for DiagnosisGroup and DiagnosisDetail are
SQL views. DiagnosisGroup is so that I can have a more succinct view of
the data, since a patient can have the same diagnosis many times. I am
wondering if there is a way to do this within the class structure
instead of at the db server?
do you mean, derive a DiagnosisGroup object from a DiagnosisDetail
without running SQL? (or a list of them?) (the answer is..sure? just
build Python code to generate objects from a list of DiagnosisDetail
objects).
I do not wish to do this through any ORM
session queries, since these two classes have distinct use cases where
they bind to wtform views. Thus, I would like to inherit the properties
of these two classes from another distinct class.
I have not been able to find anything like this, short
of [create-column-properties-that-use-a-groupby][1]
<http://stackoverflow.com/questions/25822393/how-can-i-create-column-properties-that-use-a-groupby/25879453>,
but this uses session queries to achieve the result. I would like to
keep everything within the class itself through inheritance of the
DiagnosisDetail class.
You don't need a relational database to do grouping, if you have a list
of data in memory it can be grouped using sets, or most succinctly
Python's own groupby function:
https://docs.python.org/2/library/itertools.html#itertools.groupby
Note: the primary key for DiagnosisGroup, is a concatenation of dx_code
and another field patient_id. Groupings thus are unique.
OK, so
def keyfunc(detail):
return (detail.dx_code, detail.patient_id)
def get_diagnosis_groups(sorted_list_of_diagnosis_detail):
for (dx_code, patient_id), details in
itertools.groupby(sorted_list_of_diagnosisdetail, keyfunc):
diagnosis_group = DiagnosisGroup(
dx_code, patient_id
)
diagnosis_group.details = details
for detail in details:
detail.group = diagnosis_group
yield diagnosis_group
I do also need
the FK relation back to the DiagnosisDetail class, which leads me to
believe there should be three classes, where the two above classes
inherit their properties from a parent class.
--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and
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http://www.sqlalchemy.org/
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