SQL to SQLALCHEMY - sqlalchemy

Question

Base on this post, I have this SQL query:
SELECT
id, (6371.009 * acos(cos(radians(37)) * cos(radians(lat)) *
cos(radians(lng) - radians(-122)) + sin(radians(37)) *
sin(radians(lat)))) AS distance
FROM
company
HAVING
distance < 25
ORDER BY
distance
LIMIT
0 , 20;
and I want to convert this query to SQLALCHEMY. How I can convert SQL queries that are included of functions (e.g. acos, cos, sin, radians, ...) to SQLALCHEMY queries?
I have tried this:
company_nearby = s.query(Company).filter(
(6371.009 * acos(
cos(radians(37)) * cos(radians(Company.latitude)) *
cos(radians(Company.longtitude) - radians(-122)) +
sin(radians(37)) * sin(radians(Company.latitude))
)) < 25
).limit(20).all()
But I have this error:
TypeError: a float is required
Probably because Company.latitude returns None, but company table has 16000 record with latitude and longitude.
This is Company table:
class Company(db.Model):
__tablename__ = 'company'
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(255))
latitude = db.Column(db.Float)
longtitude = db.Column(db.Float)
Any help will be much appreciated.

Answer 1

To use functions within your database you can use the func method: http://docs.sqlalchemy.org/en/latest/core/functions.html#sqlalchemy.sql.functions.func
Something like this for example:
print select([func.cos(func.radians(table.c.lng))

Answer 2

Using raw query execution is one of the methods to run SQL queries in SQLALCHEMY. for this example this is how I proceed:
from math import sqrt, radians, cos, acos, sin, pow
...
raw_con = engine.raw_connection()
raw_con.create_function("cos", 1, cos)
raw_con.create_function("acos", 1, acos)
raw_con.create_function("sin", 1, sin)
raw_con.create_function("radians", 1, radians)
raw_con.create_function("sqrt", 1, sqrt)
raw_con.create_function("pow", 1, pow)
results = []
try:
cursor = raw_con.cursor()
cursor.execute('SELECT id, '
'( 6371.009 * acos( cos( radians(37) ) * '
'cos( radians( lat ) ) * cos( radians( lng ) - radians(-122) ) + '
'sin( radians(37) ) * sin( radians( lat ) ) ) ) AS distance '
'FROM company '
'WHERE distance < 25 '
'ORDER BY distance '
'LIMIT 0 , 20 ;')
results = cursor.fetchall()
cursor.close()
finally:
raw_con.close()
and:
print results
gives:
[(68, 4958.2844864897925), (50, 4958.399769765616), (17, 4958.417639125849), (13, 4958.701413904964), (16, 4958.720521740769), (46, 4958.758729888283), (54, 4958.769050291066), (47, 4958.789468071686), (57, 4958.833125409799), (14, 4958.843715312685), (45, 4958.853
383812306), (60, 4958.870656980226), (35, 4958.901153544977), (65, 4958.901643917998), (37, 4958.941355727554), (33, 4958.974325724986), (41, 4958.985977481861), (1, 4959.002398001085), (38, 4959.093650178002), (8, 4959.142373411243)]