diff options
Diffstat (limited to 'lib/sqlalchemy/engine/mock.py')
-rw-r--r-- | lib/sqlalchemy/engine/mock.py | 118 |
1 files changed, 118 insertions, 0 deletions
diff --git a/lib/sqlalchemy/engine/mock.py b/lib/sqlalchemy/engine/mock.py new file mode 100644 index 0000000..6fcb09f --- /dev/null +++ b/lib/sqlalchemy/engine/mock.py @@ -0,0 +1,118 @@ +# engine/mock.py +# Copyright (C) 2005-2022 the SQLAlchemy authors and contributors +# <see AUTHORS file> +# +# This module is part of SQLAlchemy and is released under +# the MIT License: https://www.opensource.org/licenses/mit-license.php + +from operator import attrgetter + +from . import base +from . import url as _url +from .. import util +from ..sql import ddl + + +class MockConnection(base.Connectable): + def __init__(self, dialect, execute): + self._dialect = dialect + self.execute = execute + + engine = property(lambda s: s) + dialect = property(attrgetter("_dialect")) + name = property(lambda s: s._dialect.name) + + def schema_for_object(self, obj): + return obj.schema + + def connect(self, **kwargs): + return self + + def execution_options(self, **kw): + return self + + def compiler(self, statement, parameters, **kwargs): + return self._dialect.compiler( + statement, parameters, engine=self, **kwargs + ) + + def create(self, entity, **kwargs): + kwargs["checkfirst"] = False + + ddl.SchemaGenerator(self.dialect, self, **kwargs).traverse_single( + entity + ) + + def drop(self, entity, **kwargs): + kwargs["checkfirst"] = False + + ddl.SchemaDropper(self.dialect, self, **kwargs).traverse_single(entity) + + def _run_ddl_visitor( + self, visitorcallable, element, connection=None, **kwargs + ): + kwargs["checkfirst"] = False + visitorcallable(self.dialect, self, **kwargs).traverse_single(element) + + def execute(self, object_, *multiparams, **params): + raise NotImplementedError() + + +def create_mock_engine(url, executor, **kw): + """Create a "mock" engine used for echoing DDL. + + This is a utility function used for debugging or storing the output of DDL + sequences as generated by :meth:`_schema.MetaData.create_all` + and related methods. + + The function accepts a URL which is used only to determine the kind of + dialect to be used, as well as an "executor" callable function which + will receive a SQL expression object and parameters, which can then be + echoed or otherwise printed. The executor's return value is not handled, + nor does the engine allow regular string statements to be invoked, and + is therefore only useful for DDL that is sent to the database without + receiving any results. + + E.g.:: + + from sqlalchemy import create_mock_engine + + def dump(sql, *multiparams, **params): + print(sql.compile(dialect=engine.dialect)) + + engine = create_mock_engine('postgresql://', dump) + metadata.create_all(engine, checkfirst=False) + + :param url: A string URL which typically needs to contain only the + database backend name. + + :param executor: a callable which receives the arguments ``sql``, + ``*multiparams`` and ``**params``. The ``sql`` parameter is typically + an instance of :class:`.DDLElement`, which can then be compiled into a + string using :meth:`.DDLElement.compile`. + + .. versionadded:: 1.4 - the :func:`.create_mock_engine` function replaces + the previous "mock" engine strategy used with + :func:`_sa.create_engine`. + + .. seealso:: + + :ref:`faq_ddl_as_string` + + """ + + # create url.URL object + u = _url.make_url(url) + + dialect_cls = u.get_dialect() + + dialect_args = {} + # consume dialect arguments from kwargs + for k in util.get_cls_kwargs(dialect_cls): + if k in kw: + dialect_args[k] = kw.pop(k) + + # create dialect + dialect = dialect_cls(**dialect_args) + + return MockConnection(dialect, executor) |