On 03/06/2017 04:47 PM, Leonardo L. P. da Mata wrote:
Hello, thanks for the help.
This makes sense but it looks like that the value is calculated twice,
one in the query and the other accessing the property.
My idea is to have the result on the query return itself.
"lat" and "lng" here are variables that are in your program and are not
related to the model you have. So you're asking that a particular
object be returned with additional values stuck onto it.
The Session uses an identity map that ensures that an object of a
particular primary key is only present once; if you make two queries
which both return the same primary key, you get the same object back.
If you did two queries with different values of "lat" / "lng" that both
ultimately return the same PartnerAddress object, would the old values
be erased? It's not clear.
Instead, this "distance" you're getting is really a value associated not
just with the object but this specific query. You can get it back by
just adding it as a column:
query = session.query(PartnerV3, PartnerAddress.distance(lat,
lng)).join(PartnerAddress).order_by(PartnerAddress.distance(lat, lng))
for partnerv3, distance in query:
print distance
2017-03-06 18:31 GMT-03:00 mike bayer <mike...@zzzcomputing.com
<mailto:mike...@zzzcomputing.com>>:
On 03/06/2017 04:16 PM, Leonardo Mata wrote:
Hello, My applications does some ordering using the distance from
latitude and longitude haversine distance, i was able to
calculate this
using @hybrid.method and @.*expression, but i can't output the
calculated distance:
/class PartnerAddress(db.Model, WithTimestampsModel,
SerializeMixin):/
/ /
/ # Columns/
/ id = db.Column(db.Integer(), primary_key=True, nullable=False)/
/
/
/ partner_id = db.Column(/
/ db.Integer(),/
/ db.ForeignKey('partner.id <http://partner.id>'),/
/ nullable=False/
/ )/
/
/
/ latitude = db.Column(db.Numeric(precision=9, scale=7),
nullable=False)/
/ longitude = db.Column(db.Numeric(precision=10, scale=7),
nullable=False)/
/ /
/
/
/ @hybrid_method/
/ def distance(self, lat, lng):/
/ /
/ return math.acos(math.cos(math.radians(self.latitude)) *
math.cos(math.radians(lat)) */
/ math.cos(math.radians(self.longitude) -
math.radians(lng)) +/
/ math.sin(math.radians(self.la
<http://self.la>titude)) *
math.sin(math.radians(lat))) * 6371/
/
/
/ @distance.expression/
/ def distance(cls, lat, lng):/
/ return func.acos(func.cos(func.radians(cls.latitude)) *
func.cos(func.radians(lat)) */
/ func.cos(func.radians(lng) -
func.radians(cls.longitude)) +/
/ func.sin(func.radians(cls.latitude)) *
func.sin(func.radians(lat))) * 6371/
/
/
/
/
/class PartnerV3(db.Model, WithTimestampsModel,/
/ SoftDeletableModel, SerializeMixin):/
/ /
/
/
/ name = db.Column(db.String(128), nullable=False)/
/ /
/
/
/ address = db.relationship(/
/ 'mustafar.partner.v3.models.ad
<http://mustafar.partner.v3.models.ad>dress.PartnerAddress',/
/ backref='partner',/
/ uselist=False/
/ )/
when querying like this:
query =
PartnerV3.query.join(PartnerAddress).order_by(PartnerAddress.distance(lat,
lng)).paginate(1,10, False)
I can paginate the result, but it returns only the PartnerV3
object, i
can't access the distance.
How do I access this distance property?
you have a PartnerV3 there so the PartnerAddress is on the .address
property:
query =
PartnerV3.query.join(PartnerAddress).order_by(PartnerAddress.distance(lat,
lng))
some_partner = query.first()
partner_address = some_partner.address
distance = partner_address.distance(lat, lng)
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barr...@gmail.com <mailto:barr...@gmail.com>
"May the force be with you, always"
"Nerd Pride... eu tenho. Voce tem?"
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