336 lines
13 KiB
Python
336 lines
13 KiB
Python
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from collections import namedtuple
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import sqlparse
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from MySQLdb.constants import FIELD_TYPE
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from django.db.backends.base.introspection import BaseDatabaseIntrospection
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from django.db.backends.base.introspection import FieldInfo as BaseFieldInfo
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from django.db.backends.base.introspection import TableInfo
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from django.db.models import Index
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from django.utils.datastructures import OrderedSet
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FieldInfo = namedtuple(
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"FieldInfo", BaseFieldInfo._fields + ("extra", "is_unsigned", "has_json_constraint")
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)
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InfoLine = namedtuple(
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"InfoLine",
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"col_name data_type max_len num_prec num_scale extra column_default "
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"collation is_unsigned",
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)
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class DatabaseIntrospection(BaseDatabaseIntrospection):
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data_types_reverse = {
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FIELD_TYPE.BLOB: "TextField",
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FIELD_TYPE.CHAR: "CharField",
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FIELD_TYPE.DECIMAL: "DecimalField",
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FIELD_TYPE.NEWDECIMAL: "DecimalField",
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FIELD_TYPE.DATE: "DateField",
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FIELD_TYPE.DATETIME: "DateTimeField",
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FIELD_TYPE.DOUBLE: "FloatField",
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FIELD_TYPE.FLOAT: "FloatField",
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FIELD_TYPE.INT24: "IntegerField",
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FIELD_TYPE.JSON: "JSONField",
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FIELD_TYPE.LONG: "IntegerField",
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FIELD_TYPE.LONGLONG: "BigIntegerField",
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FIELD_TYPE.SHORT: "SmallIntegerField",
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FIELD_TYPE.STRING: "CharField",
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FIELD_TYPE.TIME: "TimeField",
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FIELD_TYPE.TIMESTAMP: "DateTimeField",
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FIELD_TYPE.TINY: "IntegerField",
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FIELD_TYPE.TINY_BLOB: "TextField",
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FIELD_TYPE.MEDIUM_BLOB: "TextField",
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FIELD_TYPE.LONG_BLOB: "TextField",
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FIELD_TYPE.VAR_STRING: "CharField",
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}
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def get_field_type(self, data_type, description):
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field_type = super().get_field_type(data_type, description)
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if "auto_increment" in description.extra:
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if field_type == "IntegerField":
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return "AutoField"
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elif field_type == "BigIntegerField":
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return "BigAutoField"
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elif field_type == "SmallIntegerField":
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return "SmallAutoField"
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if description.is_unsigned:
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if field_type == "BigIntegerField":
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return "PositiveBigIntegerField"
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elif field_type == "IntegerField":
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return "PositiveIntegerField"
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elif field_type == "SmallIntegerField":
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return "PositiveSmallIntegerField"
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# JSON data type is an alias for LONGTEXT in MariaDB, use check
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# constraints clauses to introspect JSONField.
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if description.has_json_constraint:
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return "JSONField"
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return field_type
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def get_table_list(self, cursor):
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"""Return a list of table and view names in the current database."""
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cursor.execute("SHOW FULL TABLES")
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return [
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TableInfo(row[0], {"BASE TABLE": "t", "VIEW": "v"}.get(row[1]))
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for row in cursor.fetchall()
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]
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def get_table_description(self, cursor, table_name):
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"""
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Return a description of the table with the DB-API cursor.description
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interface."
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"""
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json_constraints = {}
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if (
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self.connection.mysql_is_mariadb
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and self.connection.features.can_introspect_json_field
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):
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# JSON data type is an alias for LONGTEXT in MariaDB, select
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# JSON_VALID() constraints to introspect JSONField.
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cursor.execute(
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"""
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SELECT c.constraint_name AS column_name
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FROM information_schema.check_constraints AS c
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WHERE
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c.table_name = %s AND
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LOWER(c.check_clause) =
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'json_valid(`' + LOWER(c.constraint_name) + '`)' AND
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c.constraint_schema = DATABASE()
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""",
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[table_name],
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)
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json_constraints = {row[0] for row in cursor.fetchall()}
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# A default collation for the given table.
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cursor.execute(
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"""
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SELECT table_collation
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FROM information_schema.tables
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WHERE table_schema = DATABASE()
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AND table_name = %s
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""",
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[table_name],
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)
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row = cursor.fetchone()
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default_column_collation = row[0] if row else ""
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# information_schema database gives more accurate results for some figures:
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# - varchar length returned by cursor.description is an internal length,
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# not visible length (#5725)
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# - precision and scale (for decimal fields) (#5014)
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# - auto_increment is not available in cursor.description
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cursor.execute(
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"""
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SELECT
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column_name, data_type, character_maximum_length,
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numeric_precision, numeric_scale, extra, column_default,
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CASE
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WHEN collation_name = %s THEN NULL
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ELSE collation_name
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END AS collation_name,
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CASE
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WHEN column_type LIKE '%% unsigned' THEN 1
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ELSE 0
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END AS is_unsigned
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FROM information_schema.columns
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WHERE table_name = %s AND table_schema = DATABASE()
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""",
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[default_column_collation, table_name],
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)
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field_info = {line[0]: InfoLine(*line) for line in cursor.fetchall()}
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cursor.execute(
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"SELECT * FROM %s LIMIT 1" % self.connection.ops.quote_name(table_name)
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)
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def to_int(i):
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return int(i) if i is not None else i
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fields = []
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for line in cursor.description:
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info = field_info[line[0]]
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fields.append(
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FieldInfo(
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*line[:3],
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to_int(info.max_len) or line[3],
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to_int(info.num_prec) or line[4],
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to_int(info.num_scale) or line[5],
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line[6],
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info.column_default,
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info.collation,
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info.extra,
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info.is_unsigned,
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line[0] in json_constraints,
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)
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)
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return fields
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def get_sequences(self, cursor, table_name, table_fields=()):
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for field_info in self.get_table_description(cursor, table_name):
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if "auto_increment" in field_info.extra:
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# MySQL allows only one auto-increment column per table.
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return [{"table": table_name, "column": field_info.name}]
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return []
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def get_relations(self, cursor, table_name):
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"""
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Return a dictionary of {field_name: (field_name_other_table, other_table)}
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representing all foreign keys in the given table.
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"""
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cursor.execute(
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"""
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SELECT column_name, referenced_column_name, referenced_table_name
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FROM information_schema.key_column_usage
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WHERE table_name = %s
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AND table_schema = DATABASE()
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AND referenced_table_name IS NOT NULL
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AND referenced_column_name IS NOT NULL
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""",
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[table_name],
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)
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return {
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field_name: (other_field, other_table)
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for field_name, other_field, other_table in cursor.fetchall()
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}
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def get_storage_engine(self, cursor, table_name):
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"""
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Retrieve the storage engine for a given table. Return the default
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storage engine if the table doesn't exist.
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"""
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cursor.execute(
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"""
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SELECT engine
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FROM information_schema.tables
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WHERE
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table_name = %s AND
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table_schema = DATABASE()
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""",
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[table_name],
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)
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result = cursor.fetchone()
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if not result:
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return self.connection.features._mysql_storage_engine
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return result[0]
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def _parse_constraint_columns(self, check_clause, columns):
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check_columns = OrderedSet()
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statement = sqlparse.parse(check_clause)[0]
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tokens = (token for token in statement.flatten() if not token.is_whitespace)
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for token in tokens:
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if (
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token.ttype == sqlparse.tokens.Name
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and self.connection.ops.quote_name(token.value) == token.value
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and token.value[1:-1] in columns
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):
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check_columns.add(token.value[1:-1])
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return check_columns
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def get_constraints(self, cursor, table_name):
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"""
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Retrieve any constraints or keys (unique, pk, fk, check, index) across
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one or more columns.
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"""
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constraints = {}
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# Get the actual constraint names and columns
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name_query = """
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SELECT kc.`constraint_name`, kc.`column_name`,
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kc.`referenced_table_name`, kc.`referenced_column_name`,
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c.`constraint_type`
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FROM
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information_schema.key_column_usage AS kc,
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information_schema.table_constraints AS c
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WHERE
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kc.table_schema = DATABASE() AND
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c.table_schema = kc.table_schema AND
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c.constraint_name = kc.constraint_name AND
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c.constraint_type != 'CHECK' AND
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kc.table_name = %s
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ORDER BY kc.`ordinal_position`
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"""
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cursor.execute(name_query, [table_name])
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for constraint, column, ref_table, ref_column, kind in cursor.fetchall():
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if constraint not in constraints:
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constraints[constraint] = {
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"columns": OrderedSet(),
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"primary_key": kind == "PRIMARY KEY",
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"unique": kind in {"PRIMARY KEY", "UNIQUE"},
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"index": False,
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"check": False,
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"foreign_key": (ref_table, ref_column) if ref_column else None,
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}
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if self.connection.features.supports_index_column_ordering:
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constraints[constraint]["orders"] = []
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constraints[constraint]["columns"].add(column)
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# Add check constraints.
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if self.connection.features.can_introspect_check_constraints:
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unnamed_constraints_index = 0
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columns = {
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info.name for info in self.get_table_description(cursor, table_name)
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}
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if self.connection.mysql_is_mariadb:
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type_query = """
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SELECT c.constraint_name, c.check_clause
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FROM information_schema.check_constraints AS c
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WHERE
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c.constraint_schema = DATABASE() AND
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c.table_name = %s
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"""
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else:
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type_query = """
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SELECT cc.constraint_name, cc.check_clause
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FROM
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information_schema.check_constraints AS cc,
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information_schema.table_constraints AS tc
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WHERE
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cc.constraint_schema = DATABASE() AND
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tc.table_schema = cc.constraint_schema AND
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cc.constraint_name = tc.constraint_name AND
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tc.constraint_type = 'CHECK' AND
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tc.table_name = %s
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"""
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cursor.execute(type_query, [table_name])
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for constraint, check_clause in cursor.fetchall():
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constraint_columns = self._parse_constraint_columns(
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check_clause, columns
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)
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# Ensure uniqueness of unnamed constraints. Unnamed unique
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# and check columns constraints have the same name as
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# a column.
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if set(constraint_columns) == {constraint}:
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unnamed_constraints_index += 1
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constraint = "__unnamed_constraint_%s__" % unnamed_constraints_index
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constraints[constraint] = {
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"columns": constraint_columns,
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"primary_key": False,
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"unique": False,
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"index": False,
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"check": True,
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"foreign_key": None,
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}
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# Now add in the indexes
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cursor.execute(
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"SHOW INDEX FROM %s" % self.connection.ops.quote_name(table_name)
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)
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for table, non_unique, index, colseq, column, order, type_ in [
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x[:6] + (x[10],) for x in cursor.fetchall()
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]:
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if index not in constraints:
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constraints[index] = {
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"columns": OrderedSet(),
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"primary_key": False,
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"unique": not non_unique,
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"check": False,
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"foreign_key": None,
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}
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if self.connection.features.supports_index_column_ordering:
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constraints[index]["orders"] = []
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constraints[index]["index"] = True
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constraints[index]["type"] = (
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Index.suffix if type_ == "BTREE" else type_.lower()
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)
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constraints[index]["columns"].add(column)
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if self.connection.features.supports_index_column_ordering:
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constraints[index]["orders"].append("DESC" if order == "D" else "ASC")
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# Convert the sorted sets to lists
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for constraint in constraints.values():
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constraint["columns"] = list(constraint["columns"])
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return constraints
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