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from __future__ import annotations
from collections import namedtuple
import re
from typing import Any
from typing import Callable
from typing import Dict
from typing import List
from typing import Optional
from typing import Sequence
from typing import Set
from typing import Tuple
from typing import Type
from typing import TYPE_CHECKING
from typing import Union
from sqlalchemy import cast
from sqlalchemy import schema
from sqlalchemy import text
from . import base
from .. import util
from ..util import sqla_compat
if TYPE_CHECKING:
from typing import Literal
from typing import TextIO
from sqlalchemy.engine import Connection
from sqlalchemy.engine import Dialect
from sqlalchemy.engine.cursor import CursorResult
from sqlalchemy.engine.reflection import Inspector
from sqlalchemy.sql.elements import ClauseElement
from sqlalchemy.sql.elements import ColumnElement
from sqlalchemy.sql.elements import quoted_name
from sqlalchemy.sql.schema import Column
from sqlalchemy.sql.schema import Constraint
from sqlalchemy.sql.schema import ForeignKeyConstraint
from sqlalchemy.sql.schema import Index
from sqlalchemy.sql.schema import Table
from sqlalchemy.sql.schema import UniqueConstraint
from sqlalchemy.sql.selectable import TableClause
from sqlalchemy.sql.type_api import TypeEngine
from .base import _ServerDefault
from ..autogenerate.api import AutogenContext
from ..operations.batch import ApplyBatchImpl
from ..operations.batch import BatchOperationsImpl
class ImplMeta(type):
def __init__(
cls,
classname: str,
bases: Tuple[Type[DefaultImpl]],
dict_: Dict[str, Any],
):
newtype = type.__init__(cls, classname, bases, dict_)
if "__dialect__" in dict_:
_impls[dict_["__dialect__"]] = cls # type: ignore[assignment]
return newtype
_impls: Dict[str, Type[DefaultImpl]] = {}
Params = namedtuple("Params", ["token0", "tokens", "args", "kwargs"])
class DefaultImpl(metaclass=ImplMeta):
"""Provide the entrypoint for major migration operations,
including database-specific behavioral variances.
While individual SQL/DDL constructs already provide
for database-specific implementations, variances here
allow for entirely different sequences of operations
to take place for a particular migration, such as
SQL Server's special 'IDENTITY INSERT' step for
bulk inserts.
"""
__dialect__ = "default"
transactional_ddl = False
command_terminator = ";"
type_synonyms: Tuple[Set[str], ...] = ({"NUMERIC", "DECIMAL"},)
type_arg_extract: Sequence[str] = ()
# on_null is known to be supported only by oracle
identity_attrs_ignore: Tuple[str, ...] = ("on_null",)
def __init__(
self,
dialect: Dialect,
connection: Optional[Connection],
as_sql: bool,
transactional_ddl: Optional[bool],
output_buffer: Optional[TextIO],
context_opts: Dict[str, Any],
) -> None:
self.dialect = dialect
self.connection = connection
self.as_sql = as_sql
self.literal_binds = context_opts.get("literal_binds", False)
self.output_buffer = output_buffer
self.memo: dict = {}
self.context_opts = context_opts
if transactional_ddl is not None:
self.transactional_ddl = transactional_ddl
if self.literal_binds:
if not self.as_sql:
raise util.CommandError(
"Can't use literal_binds setting without as_sql mode"
)
@classmethod
def get_by_dialect(cls, dialect: Dialect) -> Type[DefaultImpl]:
return _impls[dialect.name]
def static_output(self, text: str) -> None:
assert self.output_buffer is not None
self.output_buffer.write(text + "\n\n")
self.output_buffer.flush()
def requires_recreate_in_batch(
self, batch_op: BatchOperationsImpl
) -> bool:
"""Return True if the given :class:`.BatchOperationsImpl`
would need the table to be recreated and copied in order to
proceed.
Normally, only returns True on SQLite when operations other
than add_column are present.
"""
return False
def prep_table_for_batch(
self, batch_impl: ApplyBatchImpl, table: Table
) -> None:
"""perform any operations needed on a table before a new
one is created to replace it in batch mode.
the PG dialect uses this to drop constraints on the table
before the new one uses those same names.
"""
@property
def bind(self) -> Optional[Connection]:
return self.connection
def _exec(
self,
construct: Union[ClauseElement, str],
execution_options: Optional[dict[str, Any]] = None,
multiparams: Sequence[dict] = (),
params: Dict[str, Any] = util.immutabledict(),
) -> Optional[CursorResult]:
if isinstance(construct, str):
construct = text(construct)
if self.as_sql:
if multiparams or params:
# TODO: coverage
raise Exception("Execution arguments not allowed with as_sql")
if self.literal_binds and not isinstance(
construct, schema.DDLElement
):
compile_kw = dict(compile_kwargs={"literal_binds": True})
else:
compile_kw = {}
compiled = construct.compile(
dialect=self.dialect, **compile_kw # type: ignore[arg-type]
)
self.static_output(
str(compiled).replace("\t", " ").strip()
+ self.command_terminator
)
return None
else:
conn = self.connection
assert conn is not None
if execution_options:
conn = conn.execution_options(**execution_options)
if params:
assert isinstance(multiparams, tuple)
multiparams += (params,)
return conn.execute( # type: ignore[call-overload]
construct, multiparams
)
def execute(
self,
sql: Union[ClauseElement, str],
execution_options: Optional[dict[str, Any]] = None,
) -> None:
self._exec(sql, execution_options)
def alter_column(
self,
table_name: str,
column_name: str,
nullable: Optional[bool] = None,
server_default: Union[_ServerDefault, Literal[False]] = False,
name: Optional[str] = None,
type_: Optional[TypeEngine] = None,
schema: Optional[str] = None,
autoincrement: Optional[bool] = None,
comment: Optional[Union[str, Literal[False]]] = False,
existing_comment: Optional[str] = None,
existing_type: Optional[TypeEngine] = None,
existing_server_default: Optional[_ServerDefault] = None,
existing_nullable: Optional[bool] = None,
existing_autoincrement: Optional[bool] = None,
**kw: Any,
) -> None:
if autoincrement is not None or existing_autoincrement is not None:
util.warn(
"autoincrement and existing_autoincrement "
"only make sense for MySQL",
stacklevel=3,
)
if nullable is not None:
self._exec(
base.ColumnNullable(
table_name,
column_name,
nullable,
schema=schema,
existing_type=existing_type,
existing_server_default=existing_server_default,
existing_nullable=existing_nullable,
existing_comment=existing_comment,
)
)
if server_default is not False:
kw = {}
cls_: Type[
Union[
base.ComputedColumnDefault,
base.IdentityColumnDefault,
base.ColumnDefault,
]
]
if sqla_compat._server_default_is_computed(
server_default, existing_server_default
):
cls_ = base.ComputedColumnDefault
elif sqla_compat._server_default_is_identity(
server_default, existing_server_default
):
cls_ = base.IdentityColumnDefault
kw["impl"] = self
else:
cls_ = base.ColumnDefault
self._exec(
cls_(
table_name,
column_name,
server_default, # type:ignore[arg-type]
schema=schema,
existing_type=existing_type,
existing_server_default=existing_server_default,
existing_nullable=existing_nullable,
existing_comment=existing_comment,
**kw,
)
)
if type_ is not None:
self._exec(
base.ColumnType(
table_name,
column_name,
type_,
schema=schema,
existing_type=existing_type,
existing_server_default=existing_server_default,
existing_nullable=existing_nullable,
existing_comment=existing_comment,
)
)
if comment is not False:
self._exec(
base.ColumnComment(
table_name,
column_name,
comment,
schema=schema,
existing_type=existing_type,
existing_server_default=existing_server_default,
existing_nullable=existing_nullable,
existing_comment=existing_comment,
)
)
# do the new name last ;)
if name is not None:
self._exec(
base.ColumnName(
table_name,
column_name,
name,
schema=schema,
existing_type=existing_type,
existing_server_default=existing_server_default,
existing_nullable=existing_nullable,
)
)
def add_column(
self,
table_name: str,
column: Column[Any],
schema: Optional[Union[str, quoted_name]] = None,
) -> None:
self._exec(base.AddColumn(table_name, column, schema=schema))
def drop_column(
self,
table_name: str,
column: Column[Any],
schema: Optional[str] = None,
**kw,
) -> None:
self._exec(base.DropColumn(table_name, column, schema=schema))
def add_constraint(self, const: Any) -> None:
if const._create_rule is None or const._create_rule(self):
self._exec(schema.AddConstraint(const))
def drop_constraint(self, const: Constraint) -> None:
self._exec(schema.DropConstraint(const))
def rename_table(
self,
old_table_name: str,
new_table_name: Union[str, quoted_name],
schema: Optional[Union[str, quoted_name]] = None,
) -> None:
self._exec(
base.RenameTable(old_table_name, new_table_name, schema=schema)
)
def create_table(self, table: Table) -> None:
table.dispatch.before_create(
table, self.connection, checkfirst=False, _ddl_runner=self
)
self._exec(schema.CreateTable(table))
table.dispatch.after_create(
table, self.connection, checkfirst=False, _ddl_runner=self
)
for index in table.indexes:
self._exec(schema.CreateIndex(index))
with_comment = (
self.dialect.supports_comments and not self.dialect.inline_comments
)
comment = table.comment
if comment and with_comment:
self.create_table_comment(table)
for column in table.columns:
comment = column.comment
if comment and with_comment:
self.create_column_comment(column)
def drop_table(self, table: Table) -> None:
table.dispatch.before_drop(
table, self.connection, checkfirst=False, _ddl_runner=self
)
self._exec(schema.DropTable(table))
table.dispatch.after_drop(
table, self.connection, checkfirst=False, _ddl_runner=self
)
def create_index(self, index: Index) -> None:
self._exec(schema.CreateIndex(index))
def create_table_comment(self, table: Table) -> None:
self._exec(schema.SetTableComment(table))
def drop_table_comment(self, table: Table) -> None:
self._exec(schema.DropTableComment(table))
def create_column_comment(self, column: ColumnElement[Any]) -> None:
self._exec(schema.SetColumnComment(column))
def drop_index(self, index: Index) -> None:
self._exec(schema.DropIndex(index))
def bulk_insert(
self,
table: Union[TableClause, Table],
rows: List[dict],
multiinsert: bool = True,
) -> None:
if not isinstance(rows, list):
raise TypeError("List expected")
elif rows and not isinstance(rows[0], dict):
raise TypeError("List of dictionaries expected")
if self.as_sql:
for row in rows:
self._exec(
sqla_compat._insert_inline(table).values(
**{
k: sqla_compat._literal_bindparam(
k, v, type_=table.c[k].type
)
if not isinstance(
v, sqla_compat._literal_bindparam
)
else v
for k, v in row.items()
}
)
)
else:
if rows:
if multiinsert:
self._exec(
sqla_compat._insert_inline(table), multiparams=rows
)
else:
for row in rows:
self._exec(
sqla_compat._insert_inline(table).values(**row)
)
def _tokenize_column_type(self, column: Column) -> Params:
definition = self.dialect.type_compiler.process(column.type).lower()
# tokenize the SQLAlchemy-generated version of a type, so that
# the two can be compared.
#
# examples:
# NUMERIC(10, 5)
# TIMESTAMP WITH TIMEZONE
# INTEGER UNSIGNED
# INTEGER (10) UNSIGNED
# INTEGER(10) UNSIGNED
# varchar character set utf8
#
tokens = re.findall(r"[\w\-_]+|\(.+?\)", definition)
term_tokens = []
paren_term = None
for token in tokens:
if re.match(r"^\(.*\)$", token):
paren_term = token
else:
term_tokens.append(token)
params = Params(term_tokens[0], term_tokens[1:], [], {})
if paren_term:
for term in re.findall("[^(),]+", paren_term):
if "=" in term:
key, val = term.split("=")
params.kwargs[key.strip()] = val.strip()
else:
params.args.append(term.strip())
return params
def _column_types_match(
self, inspector_params: Params, metadata_params: Params
) -> bool:
if inspector_params.token0 == metadata_params.token0:
return True
synonyms = [{t.lower() for t in batch} for batch in self.type_synonyms]
inspector_all_terms = " ".join(
[inspector_params.token0] + inspector_params.tokens
)
metadata_all_terms = " ".join(
[metadata_params.token0] + metadata_params.tokens
)
for batch in synonyms:
if {inspector_all_terms, metadata_all_terms}.issubset(batch) or {
inspector_params.token0,
metadata_params.token0,
}.issubset(batch):
return True
return False
def _column_args_match(
self, inspected_params: Params, meta_params: Params
) -> bool:
"""We want to compare column parameters. However, we only want
to compare parameters that are set. If they both have `collation`,
we want to make sure they are the same. However, if only one
specifies it, dont flag it for being less specific
"""
if (
len(meta_params.tokens) == len(inspected_params.tokens)
and meta_params.tokens != inspected_params.tokens
):
return False
if (
len(meta_params.args) == len(inspected_params.args)
and meta_params.args != inspected_params.args
):
return False
insp = " ".join(inspected_params.tokens).lower()
meta = " ".join(meta_params.tokens).lower()
for reg in self.type_arg_extract:
mi = re.search(reg, insp)
mm = re.search(reg, meta)
if mi and mm and mi.group(1) != mm.group(1):
return False
return True
def compare_type(
self, inspector_column: Column[Any], metadata_column: Column
) -> bool:
"""Returns True if there ARE differences between the types of the two
columns. Takes impl.type_synonyms into account between retrospected
and metadata types
"""
inspector_params = self._tokenize_column_type(inspector_column)
metadata_params = self._tokenize_column_type(metadata_column)
if not self._column_types_match(inspector_params, metadata_params):
return True
if not self._column_args_match(inspector_params, metadata_params):
return True
return False
def compare_server_default(
self,
inspector_column,
metadata_column,
rendered_metadata_default,
rendered_inspector_default,
):
return rendered_inspector_default != rendered_metadata_default
def correct_for_autogen_constraints(
self,
conn_uniques: Set[UniqueConstraint],
conn_indexes: Set[Index],
metadata_unique_constraints: Set[UniqueConstraint],
metadata_indexes: Set[Index],
) -> None:
pass
def cast_for_batch_migrate(self, existing, existing_transfer, new_type):
if existing.type._type_affinity is not new_type._type_affinity:
existing_transfer["expr"] = cast(
existing_transfer["expr"], new_type
)
def render_ddl_sql_expr(
self, expr: ClauseElement, is_server_default: bool = False, **kw: Any
) -> str:
"""Render a SQL expression that is typically a server default,
index expression, etc.
.. versionadded:: 1.0.11
"""
compile_kw = {
"compile_kwargs": {"literal_binds": True, "include_table": False}
}
return str(
expr.compile(
dialect=self.dialect, **compile_kw # type: ignore[arg-type]
)
)
def _compat_autogen_column_reflect(self, inspector: Inspector) -> Callable:
return self.autogen_column_reflect
def correct_for_autogen_foreignkeys(
self,
conn_fks: Set[ForeignKeyConstraint],
metadata_fks: Set[ForeignKeyConstraint],
) -> None:
pass
def autogen_column_reflect(self, inspector, table, column_info):
"""A hook that is attached to the 'column_reflect' event for when
a Table is reflected from the database during the autogenerate
process.
Dialects can elect to modify the information gathered here.
"""
def start_migrations(self) -> None:
"""A hook called when :meth:`.EnvironmentContext.run_migrations`
is called.
Implementations can set up per-migration-run state here.
"""
def emit_begin(self) -> None:
"""Emit the string ``BEGIN``, or the backend-specific
equivalent, on the current connection context.
This is used in offline mode and typically
via :meth:`.EnvironmentContext.begin_transaction`.
"""
self.static_output("BEGIN" + self.command_terminator)
def emit_commit(self) -> None:
"""Emit the string ``COMMIT``, or the backend-specific
equivalent, on the current connection context.
This is used in offline mode and typically
via :meth:`.EnvironmentContext.begin_transaction`.
"""
self.static_output("COMMIT" + self.command_terminator)
def render_type(
self, type_obj: TypeEngine, autogen_context: AutogenContext
) -> Union[str, Literal[False]]:
return False
def _compare_identity_default(self, metadata_identity, inspector_identity):
# ignored contains the attributes that were not considered
# because assumed to their default values in the db.
diff, ignored = _compare_identity_options(
sqla_compat._identity_attrs,
metadata_identity,
inspector_identity,
sqla_compat.Identity(),
)
meta_always = getattr(metadata_identity, "always", None)
inspector_always = getattr(inspector_identity, "always", None)
# None and False are the same in this comparison
if bool(meta_always) != bool(inspector_always):
diff.add("always")
diff.difference_update(self.identity_attrs_ignore)
# returns 3 values:
return (
# different identity attributes
diff,
# ignored identity attributes
ignored,
# if the two identity should be considered different
bool(diff) or bool(metadata_identity) != bool(inspector_identity),
)
def create_index_sig(self, index: Index) -> Tuple[Any, ...]:
# order of col matters in an index
return tuple(col.name for col in index.columns)
def _skip_functional_indexes(self, metadata_indexes, conn_indexes):
conn_indexes_by_name = {c.name: c for c in conn_indexes}
for idx in list(metadata_indexes):
if idx.name in conn_indexes_by_name:
continue
iex = sqla_compat.is_expression_index(idx)
if iex:
util.warn(
"autogenerate skipping metadata-specified "
"expression-based index "
f"{idx.name!r}; dialect {self.__dialect__!r} under "
f"SQLAlchemy {sqla_compat.sqlalchemy_version} can't "
"reflect these indexes so they can't be compared"
)
metadata_indexes.discard(idx)
def _compare_identity_options(
attributes, metadata_io, inspector_io, default_io
):
# this can be used for identity or sequence compare.
# default_io is an instance of IdentityOption with all attributes to the
# default value.
diff = set()
ignored_attr = set()
for attr in attributes:
meta_value = getattr(metadata_io, attr, None)
default_value = getattr(default_io, attr, None)
conn_value = getattr(inspector_io, attr, None)
if conn_value != meta_value:
if meta_value == default_value:
ignored_attr.add(attr)
else:
diff.add(attr)
return diff, ignored_attr
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