mock is on the way out as a general use tool.
Gregg Lind wrote:
>
> You got me there! Updating the FAQ on it would fix the issue for others.
>
> For reference:
>
> ##########################
> from sqlalchemy import *
> from sqlalchemy.schema import DDL
> from sqlalchemy.ext.declarative import declarative_base
>
> Base = declarative_base()
>
> class Data(Base):
> __tablename__ = 'data'
> f1 = Column(Integer, nullable=False, primary_key=True)
> f2 = Column(Integer, nullable=False, primary_key=True)
>
> DDL(r''' ''', on="postgres").execute_at('after-create',Data.__table__)
>
>
> def print_schema_wrong(db):
> from StringIO import StringIO
> buf = StringIO()
> engine = create_engine('%s://' % db, strategy='mock',
> executor=lambda s, p='': buf.write(s + p))
> #meta = MetaData()
> meta = Base.metadata
> meta.create_all(engine)
> print buf.getvalue()
>
>
> def print_schema(db):
> from StringIO import StringIO
> buf = StringIO()
> engine = create_engine('%s://' % db, strategy='mock',
> executor=lambda s, p='': buf.write(str(s) + p))
> #meta = MetaData()
> meta = Base.metadata
> meta.create_all(engine)
> print buf.getvalue()
>
>
> # fine
> print_schema('sqlite')
> print_schema('postgres')
> print_schema_wrong('sqlite')
>
> # will throw an error
> print_schema_wrong('postgres')
>
> ######################33
>
>
> On Fri, May 29, 2009 at 3:46 PM, Michael Bayer <[email protected]>
> wrote:
>>
>> Gregg Lind wrote:
>>>
>>> Alas, that doesn't seem to matter or help.
>>>
>>> Even this statement causes the same issue. Odd. Must not be related
>>> to the colons, alas.
>>>
>>> DDL(r''' ''', on="postgres").execute_at('after-create',Data.__table__)
>>
>> didnt realize you're printing with mock. its:
>>
>> buf.write(str(s) + p)
>>
>>
>>
>>
>>>
>>>
>>>
>>> On Fri, May 29, 2009 at 3:08 PM, Michael Bayer
>>> <[email protected]>
>>> wrote:
>>>>
>>>> Gregg Lind wrote:
>>>>>
>>>>> I used the DDL style
>>>>>
>>>>> DDL('''ALTER TABLE data ADD CONSTRAINT lowername_check CHECK
>>>>> (lowername !~ '[[\:upper\:]]')''',
>>>>> on="postgres").execute_at('after-create',Data.__table__)
>>>>>
>>>>> and now my "print_schema" method (based on
>>>>> http://www.sqlalchemy.org/trac/wiki/FAQ#HowcanIgettheCREATETABLEDROPTABLEoutputasastring)
>>>>> breaks (on PG only, because of the DDL), with this error:
>>>>>
>>>>> TypeError: unsupported operand type(s) for +: '_TextClause' and 'str'
>>>>>
>>>>> I escaped the colons in the DDL. Workarounds?
>>>>
>>>> escape them with \\: or use r'\:'
>>>>
>>>>
>>>>>
>>>>> Gregg
>>>>>
>>>>>
>>>>> Code:
>>>>>
>>>>> def print_schema(T="postgres"):
>>>>> ''' print print_schema will print the schema in use '''
>>>>> global Base
>>>>> from StringIO import StringIO
>>>>> buf = StringIO()
>>>>> print '%s://' % T
>>>>> engine = create_engine('%s://' % T, strategy='mock',
>>>>> executor=lambda s, p='': buf.write(s + p))
>>>>> Base.metadata.create_all(engine)
>>>>> return buf.getvalue()
>>>>>
>>>>>
>>>>>
>>>>> On Fri, May 29, 2009 at 12:27 PM, Gregg Lind <[email protected]>
>>>>> wrote:
>>>>>> As always, thank you for the complete, exhaustive answer. This
>>>>>> particular thing is definitely and edge case, and rather
>>>>>> non-obvious,
>>>>>> so thank you for walking me through it.
>>>>>>
>>>>>> Either of those are clean enough for me!
>>>>>>
>>>>>> Is there are more proper / general way to describe the problem, so
>>>>>> google and make this answer easier to find?
>>>>>>
>>>>>> Gregg
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Fri, May 29, 2009 at 12:10 PM, Michael Bayer
>>>>>> <[email protected]> wrote:
>>>>>>>
>>>>>>> Gregg Lind wrote:
>>>>>>>>
>>>>>>>> I use declarative base for defining classes.
>>>>>>>>
>>>>>>>> I have a constraint that only works in Postgres. How do I declare
>>>>>>>> that constraint "lowername_check" only if the session is going
>>>>>>>> postgres (and not to sqlite, for example).
>>>>>>>>
>>>>>>>> pg_only_constraint = CheckConstraint("lowername !~
>>>>>>>> '[[:upper:]]'",name='lowername_check'),
>>>>>>>> class Data(Base):
>>>>>>>> __tablename__ = 'Data'
>>>>>>>> lowername=Column(Unicode, nullable=False)
>>>>>>>> __table_args__ = (
>>>>>>>> pg_only_constraint, {}
>>>>>>>> )
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> The cleanest way is to use the schema.DDL() construct which can
>>>>>>> filter
>>>>>>> against various backends, but requires that you spell out the
>>>>>>> constraint
>>>>>>> explicitly:
>>>>>>>
>>>>>>> DDL("CREATE CONSTRAINT ....",
>>>>>>> on="postgres").execute_at('after-create',
>>>>>>> Data.__table__)
>>>>>>>
>>>>>>> Alternatively, if you want to stick with the CheckConstraint object
>>>>>>> you
>>>>>>> can create a function "create_pg_constraints()" which is called at
>>>>>>> the
>>>>>>> point your app calls "create_engine()", that contains all PG
>>>>>>> specific
>>>>>>> constructs - the function would be called based on
>>>>>>> engine.dialect.name
>>>>>>> ==
>>>>>>> "postgres".
>>>>>>>
>>>>>>> We have a more flexible architecture in 0.6 for this sort of thing
>>>>>>> and
>>>>>>> I
>>>>>>> think if we add an AddConstraint() construct there and also move
>>>>>>> most
>>>>>>> of
>>>>>>> DDL()'s execute-at and "on" functionality into the base DDLElement
>>>>>>> class,
>>>>>>> that would enable both constructs to be combined together as in
>>>>>>> AddConstraint(CheckConstraint(...args...),
>>>>>>> on="postgres")).execute_at('after-create', Data.__table__).
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> Thanks!
>>>>>>>>
>>>>>>>> Gregg Lind
>>>>>>>>
>>>>>>>> >
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> >>
>>>>>>>
>>>>>>
>>>>>
>>>>> >
>>>>>
>>>>
>>>>
>>>> >
>>>>
>>>
>>> >
>>>
>>
>>
>> >
>>
>
> >
>
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