Hi Mike,
Just verifying:
Should
class Patient(Model):
encounters = relationship(
"Encounter",
backref_populates='patient',
lazy='dynamic')
be
class Patient(Model):
encounters = relationship(
"Encounter",
back_populates='patient',
lazy='dynamic')
If this is true, I am getting an error that
Exception: can't locate strategy for <class
'sqlalchemy.orm.relationships.RelationshipProperty'> (('lazy', 'eager'),)
Btw, we rebuilt the database using patient_id as a primary key.
Thanks for your help!
Greg--
On Tuesday, May 31, 2016 at 3:49:29 PM UTC-5, Mike Bayer wrote:
>
> you should use "dynamic" and your relationships are mis-configured with
> mis-use of the backref() construct, as you've constructed relationships
> on both sides that are mutual you'd use back_populates:
>
>
> class Encounter(Model):
> patient = relationship(
> "Patient",
> back_populates='encounters',
> lazy='eager')
>
> class Patent(Model):
> encounters = relationship(
> "Encounter",
> backref_populates='patient',
> lazy='dynamic')
>
>
> Also the foreign key from Encounter.patient_id to Patient.patient_id
> does not illustrate a unique index in use and will not be accepted by
> all database backends as a real constraint unless one is added (and
> regardless, performance will suffer without an index on this column).
> Typically, Encounter.patient_id would refer to the primary key of
> Patient which is Patient.id.
>
>
>
> On 05/31/2016 04:38 PM, Horcle wrote:
> > I guess my question is: How can I efficiently load Patient and its
> > related Encounters? I have tried various loading strategies of dynamic,
> > joined (I would think this would be the desired option), subquery, no
> > load, etc., and it these do not load. On the other hand, I can load
> > Encounter just fine and access an instance of the Patient object.
> >
> >
> >
> > On Tuesday, May 31, 2016 at 11:20:37 AM UTC-5, Horcle wrote:
> >
> > I have the following two models:
> >
> > |
> > ClassEncounter(Model):
> > __tablename__ ='cp_service'
> > id =Column(Integer,primary_key=True,autoincrement=True)
> > master_service_id =Column(String(255))
> > admission_datetime =Column(DateTime)
> > admission_provider_id =Column(String(255))
> > admission_status =Column(String(255))
> > age_at_visit =Column(String(255))
> > attending_provider_id =Column(String(255))
> > center =Column(String(255))
> > department_name =Column(String(255))
> > discharge_datetime =Column(DateTime)
> > encounter_category =Column(String(255))
> > encounter_class =Column(String(255))
> > encounter_date =Column(DateTime)
> > encounter_setting =Column(String(255))
> > encounter_type =Column(String(255))
> > primary_care_provider_id =Column(String(255))
> > primary_service_yn =Column(String(255))
> > provider_id =Column(String(255))
> > serv_area_id_orig =Column(String(255))
> > service_id =Column(Integer)
> > patient_id =Column(Integer,ForeignKey('cp_patient.patient_id'))
> > patient
> >
> =relationship("Patient",backref=backref("patientEncounter"),lazy='eager',primaryjoin="Patient.patient_id==Encounter.patient_id")
>
>
> > |
> >
> > |
> > classPatient(Model):
> > __tablename__ ='cp_patient'
> > id =Column(Integer,primary_key=True,autoincrement=True)
> > first_name =Column(String(100))
> > middle_name =Column(String(80))
> > last_name =Column(String(80))
> > sex =Column(String(80))
> > race =Column(String(80))
> > birth_date =Column(DateTime)
> > ethnicity =Column(String(80))
> > race =Column(String(80))
> > patient_id =Column(Integer)
> > mrn =Column(String(80))
> > title =Column(String(80))
> > suffix =Column(String(80))
> > name_alias =Column(String(80))
> > addr_1 =Column(String(80))
> > addr_2 =Column(String(80))
> > addr_3 =Column(String(80))
> > city =Column(String(80))
> > state =Column(String(80))
> > country =Column(String(80))
> > zip =Column(String(80))
> > encounter
> >
> =relationship("Encounter",backref=backref("Patient"),lazy='dynamic',primaryjoin="Patient.patient_id==Encounter.patient_id")
>
>
> > |
> >
> >
> > Where one patient can have many encounters.
> >
> > I am able to load the patent model fine in a scaffolded list when I
> > comment out the encounter relationship in the last line (there are
> > roughly 35K patients), but when I link it to Encounters (1.7
> > million), then I am running into major performance issues. I tried
> > using lazy='dynamic', but got an error that:
> > |
> > Onrelationship Encounter.patient,'dynamic'loaders cannot be used
> > withmany-to-one/one-to-one relationships and/oruselist=False.
> > |
> >
> > What other options are there available to not load all the relations
> > until needed?
> >
> > Thanks!
> >
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