Skip to content

Data type for Float column should be float, not Decimal #178

Description

@KKawamura1

Related to: #131

About

#132 fixed #131, a bug that sqlalchemy.Numeric was treated as float, not decimal.Decimal.
But it may introduce a new bug, that sqlalchemy.Float is also treated as decimal.Decimal, not float.

To reproduce

Assigning a float value to sqlalchemy.Float is enough to reproduce this bug.

Below is a sample code to reproduce:

from decimal import Decimal
from sqlalchemy import Column, Float, Numeric, Integer
from sqlalchemy.ext.declarative import declarative_base


Base = declarative_base()


class Numbers(Base):
    __tablename__ = "numbers"
    id_ = Column(Integer, primary_key=True)

    c_numeric = Column(Numeric, nullable=False)
    c_numeric_as_decimal = Column(Numeric(asdecimal=True), nullable=False)
    c_numeric_as_float = Column(Numeric(asdecimal=False), nullable=False)
    c_float = Column(Float, nullable=False)


def in_float() -> None:
    number = 1.0
    numbers = Numbers(c_numeric=number, c_numeric_as_decimal=number, c_numeric_as_float=number, c_float=number)
    print(type(numbers.c_numeric), type(numbers.c_numeric_as_decimal), type(numbers.c_numeric_as_float), type(numbers.c_float))

def in_decimal() -> None:
    number = Decimal(1.0)
    numbers = Numbers(c_numeric=number, c_numeric_as_decimal=number, c_numeric_as_float=number, c_float=number)
    print(type(numbers.c_numeric), type(numbers.c_numeric_as_decimal), type(numbers.c_numeric_as_float), type(numbers.c_float))

in_float()
in_decimal()
$ mypy foo.py
foo.py:21: error: Incompatible type for "c_numeric" of "Numbers" (got "float", expected "Decimal")
foo.py:21: error: Incompatible type for "c_numeric_as_decimal" of "Numbers" (got "float", expected "Decimal")
foo.py:21: error: Incompatible type for "c_numeric_as_float" of "Numbers" (got "float", expected "Decimal")
foo.py:21: error: Incompatible type for "c_float" of "Numbers" (got "float", expected "Decimal")
Found 4 errors in 1 file (checked 1 source file)

Expected result

$ mypy foo.py
foo.py:21: error: Incompatible type for "c_numeric" of "Numbers" (got "float", expected "Decimal")
foo.py:21: error: Incompatible type for "c_numeric_as_decimal" of "Numbers" (got "float", expected "Decimal")
foo.py:26: error: Incompatible type for "c_numeric_as_float" of "Numbers" (got "Decimal", expected "float")  # this one
foo.py:26: error: Incompatible type for "c_float" of "Numbers" (got "Decimal", expected "float")  # this one
Found 4 errors in 1 file (checked 1 source file)

Environment

$ (cd sqlalchemy-stubs && git rev-parse HEAD)
55470ceab8149db983411d5c094c9fe16343c58b
$ python -c "import sqlalchemy; print(sqlalchemy.__version__)"
1.3.20
$ python -V
Python 3.8.2
$ mypy -V
mypy 0.790

Activity

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Metadata

Metadata

Assignees

No one assigned

    Labels

    No labels
    No labels

    Type

    No type

    Projects

    No projects

      Milestone

      No milestone

      Relationships

      None yet

      Development

      No branches or pull requests

      Issue actions