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from __future__ import annotations
import functools
from typing import Optional
from typing import TYPE_CHECKING
from typing import Union
from sqlalchemy import exc
from sqlalchemy import Integer
from sqlalchemy import types as sqltypes
from sqlalchemy.ext.compiler import compiles
from sqlalchemy.schema import Column
from sqlalchemy.schema import DDLElement
from sqlalchemy.sql.elements import quoted_name
from ..util.sqla_compat import _columns_for_constraint # noqa
from ..util.sqla_compat import _find_columns # noqa
from ..util.sqla_compat import _fk_spec # noqa
from ..util.sqla_compat import _is_type_bound # noqa
from ..util.sqla_compat import _table_for_constraint # noqa
if TYPE_CHECKING:
from typing import Any
from sqlalchemy.sql.compiler import Compiled
from sqlalchemy.sql.compiler import DDLCompiler
from sqlalchemy.sql.elements import TextClause
from sqlalchemy.sql.functions import Function
from sqlalchemy.sql.schema import FetchedValue
from sqlalchemy.sql.type_api import TypeEngine
from .impl import DefaultImpl
from ..util.sqla_compat import Computed
from ..util.sqla_compat import Identity
_ServerDefault = Union["TextClause", "FetchedValue", "Function[Any]", str]
class AlterTable(DDLElement):
"""Represent an ALTER TABLE statement.
Only the string name and optional schema name of the table
is required, not a full Table object.
"""
def __init__(
self,
table_name: str,
schema: Optional[Union[quoted_name, str]] = None,
) -> None:
self.table_name = table_name
self.schema = schema
class RenameTable(AlterTable):
def __init__(
self,
old_table_name: str,
new_table_name: Union[quoted_name, str],
schema: Optional[Union[quoted_name, str]] = None,
) -> None:
super().__init__(old_table_name, schema=schema)
self.new_table_name = new_table_name
class AlterColumn(AlterTable):
def __init__(
self,
name: str,
column_name: str,
schema: Optional[str] = None,
existing_type: Optional[TypeEngine] = None,
existing_nullable: Optional[bool] = None,
existing_server_default: Optional[_ServerDefault] = None,
existing_comment: Optional[str] = None,
) -> None:
super().__init__(name, schema=schema)
self.column_name = column_name
self.existing_type = (
sqltypes.to_instance(existing_type)
if existing_type is not None
else None
)
self.existing_nullable = existing_nullable
self.existing_server_default = existing_server_default
self.existing_comment = existing_comment
class ColumnNullable(AlterColumn):
def __init__(
self, name: str, column_name: str, nullable: bool, **kw
) -> None:
super().__init__(name, column_name, **kw)
self.nullable = nullable
class ColumnType(AlterColumn):
def __init__(
self, name: str, column_name: str, type_: TypeEngine, **kw
) -> None:
super().__init__(name, column_name, **kw)
self.type_ = sqltypes.to_instance(type_)
class ColumnName(AlterColumn):
def __init__(
self, name: str, column_name: str, newname: str, **kw
) -> None:
super().__init__(name, column_name, **kw)
self.newname = newname
class ColumnDefault(AlterColumn):
def __init__(
self,
name: str,
column_name: str,
default: Optional[_ServerDefault],
**kw,
) -> None:
super().__init__(name, column_name, **kw)
self.default = default
class ComputedColumnDefault(AlterColumn):
def __init__(
self, name: str, column_name: str, default: Optional[Computed], **kw
) -> None:
super().__init__(name, column_name, **kw)
self.default = default
class IdentityColumnDefault(AlterColumn):
def __init__(
self,
name: str,
column_name: str,
default: Optional[Identity],
impl: DefaultImpl,
**kw,
) -> None:
super().__init__(name, column_name, **kw)
self.default = default
self.impl = impl
class AddColumn(AlterTable):
def __init__(
self,
name: str,
column: Column[Any],
schema: Optional[Union[quoted_name, str]] = None,
) -> None:
super().__init__(name, schema=schema)
self.column = column
class DropColumn(AlterTable):
def __init__(
self, name: str, column: Column[Any], schema: Optional[str] = None
) -> None:
super().__init__(name, schema=schema)
self.column = column
class ColumnComment(AlterColumn):
def __init__(
self, name: str, column_name: str, comment: Optional[str], **kw
) -> None:
super().__init__(name, column_name, **kw)
self.comment = comment
@compiles(RenameTable)
def visit_rename_table(
element: RenameTable, compiler: DDLCompiler, **kw
) -> str:
return "%s RENAME TO %s" % (
alter_table(compiler, element.table_name, element.schema),
format_table_name(compiler, element.new_table_name, element.schema),
)
@compiles(AddColumn)
def visit_add_column(element: AddColumn, compiler: DDLCompiler, **kw) -> str:
return "%s %s" % (
alter_table(compiler, element.table_name, element.schema),
add_column(compiler, element.column, **kw),
)
@compiles(DropColumn)
def visit_drop_column(element: DropColumn, compiler: DDLCompiler, **kw) -> str:
return "%s %s" % (
alter_table(compiler, element.table_name, element.schema),
drop_column(compiler, element.column.name, **kw),
)
@compiles(ColumnNullable)
def visit_column_nullable(
element: ColumnNullable, compiler: DDLCompiler, **kw
) -> str:
return "%s %s %s" % (
alter_table(compiler, element.table_name, element.schema),
alter_column(compiler, element.column_name),
"DROP NOT NULL" if element.nullable else "SET NOT NULL",
)
@compiles(ColumnType)
def visit_column_type(element: ColumnType, compiler: DDLCompiler, **kw) -> str:
return "%s %s %s" % (
alter_table(compiler, element.table_name, element.schema),
alter_column(compiler, element.column_name),
"TYPE %s" % format_type(compiler, element.type_),
)
@compiles(ColumnName)
def visit_column_name(element: ColumnName, compiler: DDLCompiler, **kw) -> str:
return "%s RENAME %s TO %s" % (
alter_table(compiler, element.table_name, element.schema),
format_column_name(compiler, element.column_name),
format_column_name(compiler, element.newname),
)
@compiles(ColumnDefault)
def visit_column_default(
element: ColumnDefault, compiler: DDLCompiler, **kw
) -> str:
return "%s %s %s" % (
alter_table(compiler, element.table_name, element.schema),
alter_column(compiler, element.column_name),
"SET DEFAULT %s" % format_server_default(compiler, element.default)
if element.default is not None
else "DROP DEFAULT",
)
@compiles(ComputedColumnDefault)
def visit_computed_column(
element: ComputedColumnDefault, compiler: DDLCompiler, **kw
):
raise exc.CompileError(
'Adding or removing a "computed" construct, e.g. GENERATED '
"ALWAYS AS, to or from an existing column is not supported."
)
@compiles(IdentityColumnDefault)
def visit_identity_column(
element: IdentityColumnDefault, compiler: DDLCompiler, **kw
):
raise exc.CompileError(
'Adding, removing or modifying an "identity" construct, '
"e.g. GENERATED AS IDENTITY, to or from an existing "
"column is not supported in this dialect."
)
def quote_dotted(
name: Union[quoted_name, str], quote: functools.partial
) -> Union[quoted_name, str]:
"""quote the elements of a dotted name"""
if isinstance(name, quoted_name):
return quote(name)
result = ".".join([quote(x) for x in name.split(".")])
return result
def format_table_name(
compiler: Compiled,
name: Union[quoted_name, str],
schema: Optional[Union[quoted_name, str]],
) -> Union[quoted_name, str]:
quote = functools.partial(compiler.preparer.quote)
if schema:
return quote_dotted(schema, quote) + "." + quote(name)
else:
return quote(name)
def format_column_name(
compiler: DDLCompiler, name: Optional[Union[quoted_name, str]]
) -> Union[quoted_name, str]:
return compiler.preparer.quote(name) # type: ignore[arg-type]
def format_server_default(
compiler: DDLCompiler,
default: Optional[_ServerDefault],
) -> str:
return compiler.get_column_default_string(
Column("x", Integer, server_default=default)
)
def format_type(compiler: DDLCompiler, type_: TypeEngine) -> str:
return compiler.dialect.type_compiler.process(type_)
def alter_table(
compiler: DDLCompiler,
name: str,
schema: Optional[str],
) -> str:
return "ALTER TABLE %s" % format_table_name(compiler, name, schema)
def drop_column(compiler: DDLCompiler, name: str, **kw) -> str:
return "DROP COLUMN %s" % format_column_name(compiler, name)
def alter_column(compiler: DDLCompiler, name: str) -> str:
return "ALTER COLUMN %s" % format_column_name(compiler, name)
def add_column(compiler: DDLCompiler, column: Column[Any], **kw) -> str:
text = "ADD COLUMN %s" % compiler.get_column_specification(column, **kw)
const = " ".join(
compiler.process(constraint) for constraint in column.constraints
)
if const:
text += " " + const
return text
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