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Use .transform() instead of modifying sqlite_master for add_foreign_keys(), refs #577
This commit is contained in:
Simon Willison
parent
1dc6b5aa64
commit
842b61321f
4 changed files with 133 additions and 108 deletions
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@ -747,9 +747,16 @@ class Database:
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def resolve_foreign_keys(
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self, name: str, foreign_keys: ForeignKeysType
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) -> List[ForeignKey]:
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# foreign_keys may be a list of column names, a list of ForeignKey tuples,
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# a list of tuple-pairs or a list of tuple-triples. We want to turn
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# it into a list of ForeignKey tuples
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"""
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Given a list of differing foreign_keys definitions, return a list of
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fully resolved ForeignKey() named tuples.
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:param name: Name of table that foreign keys are being defined for
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:param foreign_keys: List of foreign keys, each of which can be a
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string, a ForeignKey() named tuple, a tuple of (column, other_table),
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or a tuple of (column, other_table, other_column), or a tuple of
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(table, column, other_table, other_column)
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"""
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table = cast(Table, self[name])
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if all(isinstance(fk, ForeignKey) for fk in foreign_keys):
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return cast(List[ForeignKey], foreign_keys)
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@ -767,6 +774,11 @@ class Database:
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), "foreign_keys= should be a list of tuples"
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fks = []
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for tuple_or_list in foreign_keys:
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if len(tuple_or_list) == 4:
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assert (
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tuple_or_list[0] == name
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), "First item in {} should have been {}".format(tuple_or_list, name)
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tuple_or_list = tuple(tuple_or_list[1:])
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assert len(tuple_or_list) in (
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2,
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3,
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@ -1148,32 +1160,14 @@ class Database:
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(table, column, other_table, other_column)
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)
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# Construct SQL for use with "UPDATE sqlite_master SET sql = ? WHERE name = ?"
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table_sql: Dict[str, str] = {}
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for table, column, other_table, other_column in foreign_keys_to_create:
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old_sql = table_sql.get(table, self[table].schema)
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extra_sql = ",\n FOREIGN KEY([{column}]) REFERENCES [{other_table}]([{other_column}])\n".format(
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column=column, other_table=other_table, other_column=other_column
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)
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# Stick that bit in at the very end just before the closing ')'
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last_paren = old_sql.rindex(")")
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new_sql = old_sql[:last_paren].strip() + extra_sql + old_sql[last_paren:]
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table_sql[table] = new_sql
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# Group them by table
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by_table = {}
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for fk in foreign_keys_to_create:
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by_table.setdefault(fk[0], []).append(fk)
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for table, fks in by_table.items():
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self[table].transform(add_foreign_keys=fks)
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# And execute it all within a single transaction
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with self.conn:
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cursor = self.conn.cursor()
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schema_version = cursor.execute("PRAGMA schema_version").fetchone()[0]
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cursor.execute("PRAGMA writable_schema = 1")
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for table_name, new_sql in table_sql.items():
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cursor.execute(
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"UPDATE sqlite_master SET sql = ? WHERE name = ?",
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(new_sql, table_name),
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)
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cursor.execute("PRAGMA schema_version = %d" % (schema_version + 1))
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cursor.execute("PRAGMA writable_schema = 0")
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# Have to VACUUM outside the transaction to ensure .foreign_keys property
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# can see the newly created foreign key.
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self.vacuum()
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def index_foreign_keys(self):
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@ -1704,7 +1698,9 @@ class Table(Queryable):
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pk: Optional[Any] = DEFAULT,
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not_null: Optional[Iterable[str]] = None,
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defaults: Optional[Dict[str, Any]] = None,
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drop_foreign_keys: Optional[Iterable] = None,
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drop_foreign_keys: Optional[Iterable[str]] = None,
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add_foreign_keys: Optional[ForeignKeysType] = None,
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foreign_keys: Optional[ForeignKeysType] = None,
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column_order: Optional[List[str]] = None,
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keep_table: Optional[str] = None,
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) -> "Table":
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@ -1721,6 +1717,8 @@ class Table(Queryable):
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:param not_null: Columns to set as ``NOT NULL``
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:param defaults: Default values for columns
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:param drop_foreign_keys: Names of columns that should have their foreign key constraints removed
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:param add_foreign_keys: List of foreign keys to add to the table
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:param foreign_keys: List of foreign keys to set for the table, replacing any existing foreign keys
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:param column_order: List of strings specifying a full or partial column order
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to use when creating the table
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:param keep_table: If specified, the existing table will be renamed to this and will not be
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@ -1735,6 +1733,8 @@ class Table(Queryable):
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not_null=not_null,
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defaults=defaults,
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drop_foreign_keys=drop_foreign_keys,
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add_foreign_keys=add_foreign_keys,
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foreign_keys=foreign_keys,
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column_order=column_order,
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keep_table=keep_table,
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)
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@ -1765,6 +1765,8 @@ class Table(Queryable):
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not_null: Optional[Iterable[str]] = None,
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defaults: Optional[Dict[str, Any]] = None,
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drop_foreign_keys: Optional[Iterable] = None,
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add_foreign_keys: Optional[ForeignKeysType] = None,
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foreign_keys: Optional[ForeignKeysType] = None,
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column_order: Optional[List[str]] = None,
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tmp_suffix: Optional[str] = None,
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keep_table: Optional[str] = None,
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@ -1779,6 +1781,8 @@ class Table(Queryable):
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:param not_null: Columns to set as ``NOT NULL``
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:param defaults: Default values for columns
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:param drop_foreign_keys: Names of columns that should have their foreign key constraints removed
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:param add_foreign_keys: List of foreign keys to add to the table
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:param foreign_keys: List of foreign keys to set for the table, replacing any existing foreign keys
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:param column_order: List of strings specifying a full or partial column order
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to use when creating the table
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:param tmp_suffix: Suffix to use for the temporary table name
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@ -1788,6 +1792,43 @@ class Table(Queryable):
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types = types or {}
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rename = rename or {}
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drop = drop or set()
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if foreign_keys is not None:
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if add_foreign_keys is not None:
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raise ValueError(
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"Cannot specify both foreign_keys and add_foreign_keys"
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)
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if drop_foreign_keys is not None:
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raise ValueError(
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"Cannot specify both foreign_keys and drop_foreign_keys"
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)
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create_table_foreign_keys = foreign_keys
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else:
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# Construct foreign_keys from current, plus add_foreign_keys, minus drop_foreign_keys
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create_table_foreign_keys = []
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for table, column, other_table, other_column in self.foreign_keys:
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# Copy over old foreign keys, unless we are dropping them
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if (drop_foreign_keys is None) or (column not in drop_foreign_keys):
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create_table_foreign_keys.append(
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ForeignKey(
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table,
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rename.get(column) or column,
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other_table,
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other_column,
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)
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)
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# Add new foreign keys
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if add_foreign_keys is not None:
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for fk in self.db.resolve_foreign_keys(self.name, add_foreign_keys):
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create_table_foreign_keys.append(
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ForeignKey(
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self.name,
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rename.get(fk.column) or fk.column,
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fk.other_table,
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fk.other_column,
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)
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)
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new_table_name = "{}_new_{}".format(
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self.name, tmp_suffix or os.urandom(6).hex()
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)
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@ -1847,14 +1888,6 @@ class Table(Queryable):
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{rename.get(c) or c: v for c, v in defaults.items()}
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)
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# foreign_keys
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create_table_foreign_keys = []
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for table, column, other_table, other_column in self.foreign_keys:
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if (drop_foreign_keys is None) or (column not in drop_foreign_keys):
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create_table_foreign_keys.append(
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(rename.get(column) or column, other_table, other_column)
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)
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if column_order is not None:
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column_order = [rename.get(col) or col for col in column_order]
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