[sqlalchemy] Re: How do I patch SQLAlchemy declarative model dynamically with Columns of different type?
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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Re: [sqlalchemy] Re: How do I patch SQLAlchemy declarative model dynamically with Columns of different type?
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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