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