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.transform(..., keep_table=name) parameter, closes #571

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Also type hints for the transform_sql() method
This commit is contained in:
Simon Willison 2023-07-22 15:32:09 -07:00
commit 61aaa69815
3 changed files with 42 additions and 13 deletions
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39
sqlite_utils/db.py
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@ -1702,6 +1702,7 @@ class Table(Queryable):
defaults: Optional[Dict[str, Any]] = None,
drop_foreign_keys: Optional[Iterable] = None,
column_order: Optional[List[str]] = None,
keep_table: Optional[str] = None,
) -> "Table":
"""
Apply an advanced alter table, including operations that are not supported by
@ -1717,7 +1718,9 @@ class Table(Queryable):
:param defaults: Default values for columns
:param drop_foreign_keys: Names of columns that should have their foreign key constraints removed
:param column_order: List of strings specifying a full or partial column order
to use when creating the table.
to use when creating the table
:param keep_table: If specified, the existing table will be renamed to this and will not be
dropped
"""
assert self.exists(), "Cannot transform a table that doesn't exist yet"
sqls = self.transform_sql(
@ -1729,6 +1732,7 @@ class Table(Queryable):
defaults=defaults,
drop_foreign_keys=drop_foreign_keys,
column_order=column_order,
keep_table=keep_table,
)
pragma_foreign_keys_was_on = self.db.execute("PRAGMA foreign_keys").fetchone()[
0
@ -1750,15 +1754,16 @@ class Table(Queryable):
def transform_sql(
self,
*,
types=None,
rename=None,
drop=None,
pk=DEFAULT,
not_null=None,
defaults=None,
drop_foreign_keys=None,
column_order=None,
tmp_suffix=None,
types: Optional[dict] = None,
rename: Optional[dict] = None,
drop: Optional[Iterable] = None,
pk: Optional[Any] = DEFAULT,
not_null: Optional[Iterable[str]] = None,
defaults: Optional[Dict[str, Any]] = None,
drop_foreign_keys: Optional[Iterable] = None,
column_order: Optional[List[str]] = None,
tmp_suffix: Optional[str] = None,
keep_table: Optional[str] = None,
) -> List[str]:
"""
Return a list of SQL statements that should be executed in order to apply this transformation.
@ -1771,7 +1776,10 @@ class Table(Queryable):
:param defaults: Default values for columns
:param drop_foreign_keys: Names of columns that should have their foreign key constraints removed
:param column_order: List of strings specifying a full or partial column order
to use when creating the table.
to use when creating the table
:param tmp_suffix: Suffix to use for the temporary table name
:param keep_table: If specified, the existing table will be renamed to this and will not be
dropped
"""
types = types or {}
rename = rename or {}
@ -1872,8 +1880,13 @@ class Table(Queryable):
new_cols=", ".join("[{}]".format(col) for col in new_cols),
)
sqls.append(copy_sql)
# Drop the old table
sqls.append("DROP TABLE [{}];".format(self.name))
# Drop (or keep) the old table
if keep_table:
sqls.append(
"ALTER TABLE [{}] RENAME TO [{}];".format(self.name, keep_table)
)
else:
sqls.append("DROP TABLE [{}];".format(self.name))
# Rename the new one
sqls.append(
"ALTER TABLE [{}] RENAME TO [{}];".format(new_table_name, self.name)