On Mon, Mar 19, 2018 at 12:52 AM, lone ois <[email protected]> wrote:
> Hi!
> i test sqlalchemy 1.1.12 - 1.2.5
> create table check constraint.
> -----------------------------------
> class testTable(db):
> __tablename__ = 'testTable'
>
> id = Column(INT, primary_key = True, autoincrement = True, unique =
> True)
> ser = Column(INT)
>
> CheckConstraint('ser>100')
>
> #sqlalchemy echo and pgadmin4
>
> CREATE TABLE "testTable" (
> id SERIAL NOT NULL,
> ser INTEGER,
> PRIMARY KEY (id),
> UNIQUE (id)
>
> no check constraint.
> ------------------------------
> class testTable(db):
> __tablename__ = 'testTable'
>
> id = Column(INT, primary_key = True, autoincrement = True, unique =
> True)
> ser = Column(INT)
> __table_args__ = (
> CheckConstraint('ser>100'),
> )
>
>
> #sqlalchemy echo
> CREATE TABLE "testTable" (
> id SERIAL NOT NULL,
> ser INTEGER,
> PRIMARY KEY (id),
> CHECK (ser>100),
> UNIQUE (id)
>
> this OK!
>
> so, i must use __table_args__ define CheckConstraint ??
when you add an object to a Python class:
class MyClass(object):
# ....
"hello!"
that string "hello" has no way of being intercepted by the class and
it knows nothing about it. SQLAlchemy's declarative has no way to see
this. So with your CheckConstraint example, this suggests that yes,
you do need to use __table_args__. However, there is an exception,
which is probably what you discovered, if you make a UniqueConstraint
or CheckConstraint that refers to the Column objects directly,
SQLAlchemy figures this out:
class MyClass(Base):
# ...
foo = Column(...)
bar = Column(...)
CheckConstraint("foo > bar")
vs.
class MyClass(Base):
# ...
foo = Column(...)
bar = Column(...)
CheckContraint(foo > bar)
That said, you should really use __table_args__ for these as that is
the idiomatic approach and will work consistently in all cases.
>
>
>
>
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
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--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
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