Third Party Integration Issues¶
I’m getting errors related to “numpy.int64
”, “numpy.bool_
”, etc.¶
The numpy package has its own numeric datatypes that extend from Python’s numeric types, but contain some behaviors that in some cases make them impossible to reconcile with some of SQLAlchemy’s behaviors, as well as in some cases with those of the underlying DBAPI driver in use.
Two errors which can occur are ProgrammingError: can't adapt type 'numpy.int64'
on a backend such as psycopg2, and ArgumentError: SQL expression object
expected, got object of type <class 'numpy.bool_'> instead
; in
more recent versions of SQLAlchemy this may be ArgumentError: SQL expression
for WHERE/HAVING role expected, got True
.
In the first case, the issue is due to psycopg2 not having an appropriate
lookup entry for the int64
datatype such that it is not accepted directly
by queries. This may be illustrated from code based on the following:
import numpy
class A(Base):
__tablename__ = "a"
id = Column(Integer, primary_key=True)
data = Column(Integer)
# .. later
session.add(A(data=numpy.int64(10)))
session.commit()
In the latter case, the issue is due to the numpy.int64
datatype overriding
the __eq__()
method and enforcing that the return type of an expression is
numpy.True
or numpy.False
, which breaks SQLAlchemy’s expression
language behavior that expects to return ColumnElement
expressions from Python equality comparisons:
>>> import numpy
>>> from sqlalchemy import column, Integer
>>> print(column("x", Integer) == numpy.int64(10)) # works
x = :x_1
>>> print(numpy.int64(10) == column("x", Integer)) # breaks
False
These errors are both solved in the same way, which is that special numpy
datatypes need to be replaced with regular Python values. Examples include
applying the Python int()
function to types like numpy.int32
and
numpy.int64
and the Python float()
function to numpy.float32
:
data = numpy.int64(10)
session.add(A(data=int(data)))
result = session.execute(select(A.data).where(int(data) == A.data))
session.commit()
SQL expression for WHERE/HAVING role expected, got True¶
See I’m getting errors related to “numpy.int64”, “numpy.bool_”, etc..
SQLAlchemy 1.4
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 Frequently Asked Questions
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 Frequently Asked Questions