Ha! Yes, I should not have taken this literally. Will try tomorrow and let
you know the outcome.
Thanks!
On Wednesday, June 1, 2016 at 3:55:35 PM UTC-5, Mike Bayer wrote:
>
> there's no "eager" strategy. you'd want something like lazy="joined" or
> something like that. check the docs.
>
>
>
> On 06/01/2016 04:19 PM, Horcle wrote:
> > 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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