mutation of Table objects in-place is not something SQLAlchemy supports.
I would advise using an extension method to TypeEngine called
with_variant() (search the docs for it, cut and paste is not working on
this terminal ) which allows a single type object, like a String(), to
produce multiple variants per backend, such as mysql.VARCHAR() only on the
mysql backend, plain String/VARCHAR on others.
gostones wrote:
> Does anyone have an idea what I may be doing wrong?
>
> Thanks for your help in advance.
>
>
> On May 11, 4:29 pm, gostones <gosto...@gmail.com> wrote:
>> I am running mysql in production but would like to run a simple tests
>> in a sqlite in memory db.
>>
>> The legacy mysql db has tables with columns that are mysql specific
>> types, Which are declared in declarative models (subclassing
>> declarative_base). I would like to run some simple tests without going
>> to mysql and so would need to swap out the columns of the model.
>>
>> How do I do this? I've tried writing a patcher/unpatcher to swap out
>> table in my model, but when I run some tests, I get
>>
>> OperationalError: (OperationalError) near ")": syntax error u'\nCREATE
>> TABLE my_table (\n)\n\n' ()
>>
>> Which makes my think that I am not patching the columns properly.
>>
>> Does anyone know how I can do this? What am I doing wrong?
>>
>> Currently, I create new columns and attach brand new Table object to
>> __table__ and save the old table.
>>
>> The DB is created, create_all() is and convert_columns is run in
>> setUp. drop_all() and revert_columns is run during tearDown in my
>> tests
>>
>> mysql_sqlite_mapping = {INTEGER: Integer,
>> MEDIUMINT: Integer,
>> TEXT: text}
>>
>> def convert_columns(self, my_class, mapping):
>> for column in my_class.__table__.columns:
>> if type(column.type) in mapping:
>> replacement_col = Column(column.name,
>> mapping[type(column.type)],
>> primary_key=column.primary_key,
>> nullable=column.nullable,
>> key=column.key,
>> unique=column.unique)
>>
>> converted_columns.append(replacement_col)
>>
>> self.registry[my_class] = my_class.__table__
>>
>> my_class.__table__.metadata.remove(my_class.__table__)
>> my_class.__table__ = Table(my_class.__table__.name,
>> my_class.__table__.metadata)
>>
>> for column in converted_columns:
>> my_class.__table__.append_column(column)
>>
>> return my_class
>>
>> def revert_columns(self, my_class):
>> saved_table = self.registry[my_class]
>>
>> metadata = my_class.__table__.metadata
>> my_class.__table__.metadata.remove(my_class.__table__)
>>
>> model_class.__table__ = Table(saved_table.name,
>> metadata)
>>
>> for column in saved_table.columns:
>> column.table = None
>> my_class.__table__.append_column(column)
>>
>> self.registry.pop(my_class)
>
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