Mini Shell
from __future__ import annotations
from typing import Any
from typing import Dict
from typing import List
from typing import Optional
from typing import Tuple
from typing import TYPE_CHECKING
from typing import Union
from sqlalchemy import CheckConstraint
from sqlalchemy import Column
from sqlalchemy import ForeignKeyConstraint
from sqlalchemy import Index
from sqlalchemy import MetaData
from sqlalchemy import PrimaryKeyConstraint
from sqlalchemy import schema as sql_schema
from sqlalchemy import Table
from sqlalchemy import types as sqltypes
from sqlalchemy.events import SchemaEventTarget
from sqlalchemy.util import OrderedDict
from sqlalchemy.util import topological
from ..util import exc
from ..util.sqla_compat import _columns_for_constraint
from ..util.sqla_compat import _copy
from ..util.sqla_compat import _copy_expression
from ..util.sqla_compat import _ensure_scope_for_ddl
from ..util.sqla_compat import _fk_is_self_referential
from ..util.sqla_compat import _idx_table_bound_expressions
from ..util.sqla_compat import _insert_inline
from ..util.sqla_compat import _is_type_bound
from ..util.sqla_compat import _remove_column_from_collection
from ..util.sqla_compat import _resolve_for_variant
from ..util.sqla_compat import _select
from ..util.sqla_compat import constraint_name_defined
from ..util.sqla_compat import constraint_name_string
if TYPE_CHECKING:
from typing import Literal
from sqlalchemy.engine import Dialect
from sqlalchemy.sql.elements import ColumnClause
from sqlalchemy.sql.elements import quoted_name
from sqlalchemy.sql.functions import Function
from sqlalchemy.sql.schema import Constraint
from sqlalchemy.sql.type_api import TypeEngine
from ..ddl.impl import DefaultImpl
class BatchOperationsImpl:
def __init__(
self,
operations,
table_name,
schema,
recreate,
copy_from,
table_args,
table_kwargs,
reflect_args,
reflect_kwargs,
naming_convention,
partial_reordering,
):
self.operations = operations
self.table_name = table_name
self.schema = schema
if recreate not in ("auto", "always", "never"):
raise ValueError(
"recreate may be one of 'auto', 'always', or 'never'."
)
self.recreate = recreate
self.copy_from = copy_from
self.table_args = table_args
self.table_kwargs = dict(table_kwargs)
self.reflect_args = reflect_args
self.reflect_kwargs = dict(reflect_kwargs)
self.reflect_kwargs.setdefault(
"listeners", list(self.reflect_kwargs.get("listeners", ()))
)
self.reflect_kwargs["listeners"].append(
("column_reflect", operations.impl.autogen_column_reflect)
)
self.naming_convention = naming_convention
self.partial_reordering = partial_reordering
self.batch = []
@property
def dialect(self) -> Dialect:
return self.operations.impl.dialect
@property
def impl(self) -> DefaultImpl:
return self.operations.impl
def _should_recreate(self) -> bool:
if self.recreate == "auto":
return self.operations.impl.requires_recreate_in_batch(self)
elif self.recreate == "always":
return True
else:
return False
def flush(self) -> None:
should_recreate = self._should_recreate()
with _ensure_scope_for_ddl(self.impl.connection):
if not should_recreate:
for opname, arg, kw in self.batch:
fn = getattr(self.operations.impl, opname)
fn(*arg, **kw)
else:
if self.naming_convention:
m1 = MetaData(naming_convention=self.naming_convention)
else:
m1 = MetaData()
if self.copy_from is not None:
existing_table = self.copy_from
reflected = False
else:
if self.operations.migration_context.as_sql:
raise exc.CommandError(
f"This operation cannot proceed in --sql mode; "
f"batch mode with dialect "
f"{self.operations.migration_context.dialect.name} " # noqa: E501
f"requires a live database connection with which "
f'to reflect the table "{self.table_name}". '
f"To generate a batch SQL migration script using "
"table "
'"move and copy", a complete Table object '
f'should be passed to the "copy_from" argument '
"of the batch_alter_table() method so that table "
"reflection can be skipped."
)
existing_table = Table(
self.table_name,
m1,
schema=self.schema,
autoload_with=self.operations.get_bind(),
*self.reflect_args,
**self.reflect_kwargs,
)
reflected = True
batch_impl = ApplyBatchImpl(
self.impl,
existing_table,
self.table_args,
self.table_kwargs,
reflected,
partial_reordering=self.partial_reordering,
)
for opname, arg, kw in self.batch:
fn = getattr(batch_impl, opname)
fn(*arg, **kw)
batch_impl._create(self.impl)
def alter_column(self, *arg, **kw) -> None:
self.batch.append(("alter_column", arg, kw))
def add_column(self, *arg, **kw) -> None:
if (
"insert_before" in kw or "insert_after" in kw
) and not self._should_recreate():
raise exc.CommandError(
"Can't specify insert_before or insert_after when using "
"ALTER; please specify recreate='always'"
)
self.batch.append(("add_column", arg, kw))
def drop_column(self, *arg, **kw) -> None:
self.batch.append(("drop_column", arg, kw))
def add_constraint(self, const: Constraint) -> None:
self.batch.append(("add_constraint", (const,), {}))
def drop_constraint(self, const: Constraint) -> None:
self.batch.append(("drop_constraint", (const,), {}))
def rename_table(self, *arg, **kw):
self.batch.append(("rename_table", arg, kw))
def create_index(self, idx: Index) -> None:
self.batch.append(("create_index", (idx,), {}))
def drop_index(self, idx: Index) -> None:
self.batch.append(("drop_index", (idx,), {}))
def create_table_comment(self, table):
self.batch.append(("create_table_comment", (table,), {}))
def drop_table_comment(self, table):
self.batch.append(("drop_table_comment", (table,), {}))
def create_table(self, table):
raise NotImplementedError("Can't create table in batch mode")
def drop_table(self, table):
raise NotImplementedError("Can't drop table in batch mode")
def create_column_comment(self, column):
self.batch.append(("create_column_comment", (column,), {}))
class ApplyBatchImpl:
def __init__(
self,
impl: DefaultImpl,
table: Table,
table_args: tuple,
table_kwargs: Dict[str, Any],
reflected: bool,
partial_reordering: tuple = (),
) -> None:
self.impl = impl
self.table = table # this is a Table object
self.table_args = table_args
self.table_kwargs = table_kwargs
self.temp_table_name = self._calc_temp_name(table.name)
self.new_table: Optional[Table] = None
self.partial_reordering = partial_reordering # tuple of tuples
self.add_col_ordering: Tuple[
Tuple[str, str], ...
] = () # tuple of tuples
self.column_transfers = OrderedDict(
(c.name, {"expr": c}) for c in self.table.c
)
self.existing_ordering = list(self.column_transfers)
self.reflected = reflected
self._grab_table_elements()
@classmethod
def _calc_temp_name(cls, tablename: Union[quoted_name, str]) -> str:
return ("_alembic_tmp_%s" % tablename)[0:50]
def _grab_table_elements(self) -> None:
schema = self.table.schema
self.columns: Dict[str, Column[Any]] = OrderedDict()
for c in self.table.c:
c_copy = _copy(c, schema=schema)
c_copy.unique = c_copy.index = False
# ensure that the type object was copied,
# as we may need to modify it in-place
if isinstance(c.type, SchemaEventTarget):
assert c_copy.type is not c.type
self.columns[c.name] = c_copy
self.named_constraints: Dict[str, Constraint] = {}
self.unnamed_constraints = []
self.col_named_constraints = {}
self.indexes: Dict[str, Index] = {}
self.new_indexes: Dict[str, Index] = {}
for const in self.table.constraints:
if _is_type_bound(const):
continue
elif (
self.reflected
and isinstance(const, CheckConstraint)
and not const.name
):
# TODO: we are skipping unnamed reflected CheckConstraint
# because
# we have no way to determine _is_type_bound() for these.
pass
elif constraint_name_string(const.name):
self.named_constraints[const.name] = const
else:
self.unnamed_constraints.append(const)
if not self.reflected:
for col in self.table.c:
for const in col.constraints:
if const.name:
self.col_named_constraints[const.name] = (col, const)
for idx in self.table.indexes:
self.indexes[idx.name] = idx # type: ignore[index]
for k in self.table.kwargs:
self.table_kwargs.setdefault(k, self.table.kwargs[k])
def _adjust_self_columns_for_partial_reordering(self) -> None:
pairs = set()
col_by_idx = list(self.columns)
if self.partial_reordering:
for tuple_ in self.partial_reordering:
for index, elem in enumerate(tuple_):
if index > 0:
pairs.add((tuple_[index - 1], elem))
else:
for index, elem in enumerate(self.existing_ordering):
if index > 0:
pairs.add((col_by_idx[index - 1], elem))
pairs.update(self.add_col_ordering)
# this can happen if some columns were dropped and not removed
# from existing_ordering. this should be prevented already, but
# conservatively making sure this didn't happen
pairs_list = [p for p in pairs if p[0] != p[1]]
sorted_ = list(
topological.sort(pairs_list, col_by_idx, deterministic_order=True)
)
self.columns = OrderedDict((k, self.columns[k]) for k in sorted_)
self.column_transfers = OrderedDict(
(k, self.column_transfers[k]) for k in sorted_
)
def _transfer_elements_to_new_table(self) -> None:
assert self.new_table is None, "Can only create new table once"
m = MetaData()
schema = self.table.schema
if self.partial_reordering or self.add_col_ordering:
self._adjust_self_columns_for_partial_reordering()
self.new_table = new_table = Table(
self.temp_table_name,
m,
*(list(self.columns.values()) + list(self.table_args)),
schema=schema,
**self.table_kwargs,
)
for const in (
list(self.named_constraints.values()) + self.unnamed_constraints
):
const_columns = {c.key for c in _columns_for_constraint(const)}
if not const_columns.issubset(self.column_transfers):
continue
const_copy: Constraint
if isinstance(const, ForeignKeyConstraint):
if _fk_is_self_referential(const):
# for self-referential constraint, refer to the
# *original* table name, and not _alembic_batch_temp.
# This is consistent with how we're handling
# FK constraints from other tables; we assume SQLite
# no foreign keys just keeps the names unchanged, so
# when we rename back, they match again.
const_copy = _copy(
const, schema=schema, target_table=self.table
)
else:
# "target_table" for ForeignKeyConstraint.copy() is
# only used if the FK is detected as being
# self-referential, which we are handling above.
const_copy = _copy(const, schema=schema)
else:
const_copy = _copy(
const, schema=schema, target_table=new_table
)
if isinstance(const, ForeignKeyConstraint):
self._setup_referent(m, const)
new_table.append_constraint(const_copy)
def _gather_indexes_from_both_tables(self) -> List[Index]:
assert self.new_table is not None
idx: List[Index] = []
for idx_existing in self.indexes.values():
# this is a lift-and-move from Table.to_metadata
if idx_existing._column_flag: # type: ignore
continue
idx_copy = Index(
idx_existing.name,
unique=idx_existing.unique,
*[
_copy_expression(expr, self.new_table)
for expr in _idx_table_bound_expressions(idx_existing)
],
_table=self.new_table,
**idx_existing.kwargs,
)
idx.append(idx_copy)
for index in self.new_indexes.values():
idx.append(
Index(
index.name,
unique=index.unique,
*[self.new_table.c[col] for col in index.columns.keys()],
**index.kwargs,
)
)
return idx
def _setup_referent(
self, metadata: MetaData, constraint: ForeignKeyConstraint
) -> None:
spec = constraint.elements[
0
]._get_colspec() # type:ignore[attr-defined]
parts = spec.split(".")
tname = parts[-2]
if len(parts) == 3:
referent_schema = parts[0]
else:
referent_schema = None
if tname != self.temp_table_name:
key = sql_schema._get_table_key(tname, referent_schema)
def colspec(elem: Any):
return elem._get_colspec()
if key in metadata.tables:
t = metadata.tables[key]
for elem in constraint.elements:
colname = colspec(elem).split(".")[-1]
if colname not in t.c:
t.append_column(Column(colname, sqltypes.NULLTYPE))
else:
Table(
tname,
metadata,
*[
Column(n, sqltypes.NULLTYPE)
for n in [
colspec(elem).split(".")[-1]
for elem in constraint.elements
]
],
schema=referent_schema,
)
def _create(self, op_impl: DefaultImpl) -> None:
self._transfer_elements_to_new_table()
op_impl.prep_table_for_batch(self, self.table)
assert self.new_table is not None
op_impl.create_table(self.new_table)
try:
op_impl._exec(
_insert_inline(self.new_table).from_select(
list(
k
for k, transfer in self.column_transfers.items()
if "expr" in transfer
),
_select(
*[
transfer["expr"]
for transfer in self.column_transfers.values()
if "expr" in transfer
]
),
)
)
op_impl.drop_table(self.table)
except:
op_impl.drop_table(self.new_table)
raise
else:
op_impl.rename_table(
self.temp_table_name, self.table.name, schema=self.table.schema
)
self.new_table.name = self.table.name
try:
for idx in self._gather_indexes_from_both_tables():
op_impl.create_index(idx)
finally:
self.new_table.name = self.temp_table_name
def alter_column(
self,
table_name: str,
column_name: str,
nullable: Optional[bool] = None,
server_default: Optional[Union[Function[Any], str, bool]] = False,
name: Optional[str] = None,
type_: Optional[TypeEngine] = None,
autoincrement: Optional[Union[bool, Literal["auto"]]] = None,
comment: Union[str, Literal[False]] = False,
**kw,
) -> None:
existing = self.columns[column_name]
existing_transfer: Dict[str, Any] = self.column_transfers[column_name]
if name is not None and name != column_name:
# note that we don't change '.key' - we keep referring
# to the renamed column by its old key in _create(). neat!
existing.name = name
existing_transfer["name"] = name
existing_type = kw.get("existing_type", None)
if existing_type:
resolved_existing_type = _resolve_for_variant(
kw["existing_type"], self.impl.dialect
)
# pop named constraints for Boolean/Enum for rename
if (
isinstance(resolved_existing_type, SchemaEventTarget)
and resolved_existing_type.name # type:ignore[attr-defined] # noqa E501
):
self.named_constraints.pop(
resolved_existing_type.name, # type:ignore[attr-defined] # noqa E501
None,
)
if type_ is not None:
type_ = sqltypes.to_instance(type_)
# old type is being discarded so turn off eventing
# rules. Alternatively we can
# erase the events set up by this type, but this is simpler.
# we also ignore the drop_constraint that will come here from
# Operations.implementation_for(alter_column)
if isinstance(existing.type, SchemaEventTarget):
existing.type._create_events = ( # type:ignore[attr-defined]
existing.type.create_constraint # type:ignore[attr-defined] # noqa
) = False
self.impl.cast_for_batch_migrate(
existing, existing_transfer, type_
)
existing.type = type_
# we *dont* however set events for the new type, because
# alter_column is invoked from
# Operations.implementation_for(alter_column) which already
# will emit an add_constraint()
if nullable is not None:
existing.nullable = nullable
if server_default is not False:
if server_default is None:
existing.server_default = None
else:
sql_schema.DefaultClause(
server_default # type: ignore[arg-type]
)._set_parent( # type:ignore[attr-defined]
existing
)
if autoincrement is not None:
existing.autoincrement = bool(autoincrement)
if comment is not False:
existing.comment = comment
def _setup_dependencies_for_add_column(
self,
colname: str,
insert_before: Optional[str],
insert_after: Optional[str],
) -> None:
index_cols = self.existing_ordering
col_indexes = {name: i for i, name in enumerate(index_cols)}
if not self.partial_reordering:
if insert_after:
if not insert_before:
if insert_after in col_indexes:
# insert after an existing column
idx = col_indexes[insert_after] + 1
if idx < len(index_cols):
insert_before = index_cols[idx]
else:
# insert after a column that is also new
insert_before = dict(self.add_col_ordering)[
insert_after
]
if insert_before:
if not insert_after:
if insert_before in col_indexes:
# insert before an existing column
idx = col_indexes[insert_before] - 1
if idx >= 0:
insert_after = index_cols[idx]
else:
# insert before a column that is also new
insert_after = {
b: a for a, b in self.add_col_ordering
}[insert_before]
if insert_before:
self.add_col_ordering += ((colname, insert_before),)
if insert_after:
self.add_col_ordering += ((insert_after, colname),)
if (
not self.partial_reordering
and not insert_before
and not insert_after
and col_indexes
):
self.add_col_ordering += ((index_cols[-1], colname),)
def add_column(
self,
table_name: str,
column: Column[Any],
insert_before: Optional[str] = None,
insert_after: Optional[str] = None,
**kw,
) -> None:
self._setup_dependencies_for_add_column(
column.name, insert_before, insert_after
)
# we copy the column because operations.add_column()
# gives us a Column that is part of a Table already.
self.columns[column.name] = _copy(column, schema=self.table.schema)
self.column_transfers[column.name] = {}
def drop_column(
self,
table_name: str,
column: Union[ColumnClause[Any], Column[Any]],
**kw,
) -> None:
if column.name in self.table.primary_key.columns:
_remove_column_from_collection(
self.table.primary_key.columns, column
)
del self.columns[column.name]
del self.column_transfers[column.name]
self.existing_ordering.remove(column.name)
# pop named constraints for Boolean/Enum for rename
if (
"existing_type" in kw
and isinstance(kw["existing_type"], SchemaEventTarget)
and kw["existing_type"].name # type:ignore[attr-defined]
):
self.named_constraints.pop(
kw["existing_type"].name, None # type:ignore[attr-defined]
)
def create_column_comment(self, column):
"""the batch table creation function will issue create_column_comment
on the real "impl" as part of the create table process.
That is, the Column object will have the comment on it already,
so when it is received by add_column() it will be a normal part of
the CREATE TABLE and doesn't need an extra step here.
"""
def create_table_comment(self, table):
"""the batch table creation function will issue create_table_comment
on the real "impl" as part of the create table process.
"""
def drop_table_comment(self, table):
"""the batch table creation function will issue drop_table_comment
on the real "impl" as part of the create table process.
"""
def add_constraint(self, const: Constraint) -> None:
if not constraint_name_defined(const.name):
raise ValueError("Constraint must have a name")
if isinstance(const, sql_schema.PrimaryKeyConstraint):
if self.table.primary_key in self.unnamed_constraints:
self.unnamed_constraints.remove(self.table.primary_key)
if constraint_name_string(const.name):
self.named_constraints[const.name] = const
else:
self.unnamed_constraints.append(const)
def drop_constraint(self, const: Constraint) -> None:
if not const.name:
raise ValueError("Constraint must have a name")
try:
if const.name in self.col_named_constraints:
col, const = self.col_named_constraints.pop(const.name)
for col_const in list(self.columns[col.name].constraints):
if col_const.name == const.name:
self.columns[col.name].constraints.remove(col_const)
elif constraint_name_string(const.name):
const = self.named_constraints.pop(const.name)
elif const in self.unnamed_constraints:
self.unnamed_constraints.remove(const)
except KeyError:
if _is_type_bound(const):
# type-bound constraints are only included in the new
# table via their type object in any case, so ignore the
# drop_constraint() that comes here via the
# Operations.implementation_for(alter_column)
return
raise ValueError("No such constraint: '%s'" % const.name)
else:
if isinstance(const, PrimaryKeyConstraint):
for col in const.columns:
self.columns[col.name].primary_key = False
def create_index(self, idx: Index) -> None:
self.new_indexes[idx.name] = idx # type: ignore[index]
def drop_index(self, idx: Index) -> None:
try:
del self.indexes[idx.name] # type: ignore[arg-type]
except KeyError:
raise ValueError("No such index: '%s'" % idx.name)
def rename_table(self, *arg, **kw):
raise NotImplementedError("TODO")
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