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from django.db.backends import BaseDatabaseIntrospection
from MySQLdb import ProgrammingError, OperationalError
from MySQLdb.constants import FIELD_TYPE
import re
foreign_key_re = re.compile(r"\sCONSTRAINT `[^`]*` FOREIGN KEY \(`([^`]*)`\) REFERENCES `([^`]*)` \(`([^`]*)`\)")
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.LONG: 'IntegerField',
FIELD_TYPE.LONGLONG: 'IntegerField',
FIELD_TYPE.SHORT: 'IntegerField',
FIELD_TYPE.STRING: 'CharField',
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_table_list(self, cursor):
"Returns a list of table names in the current database."
cursor.execute("SHOW TABLES")
return [row[0] for row in cursor.fetchall()]
def get_table_description(self, cursor, table_name):
"Returns a description of the table, with the DB-API cursor.description interface."
cursor.execute("SELECT * FROM %s LIMIT 1" % self.connection.ops.quote_name(table_name))
return cursor.description
def _name_to_index(self, cursor, table_name):
"""
Returns a dictionary of {field_name: field_index} for the given table.
Indexes are 0-based.
"""
return dict([(d[0], i) for i, d in enumerate(self.get_table_description(cursor, table_name))])
def get_relations(self, cursor, table_name):
"""
Returns a dictionary of {field_index: (field_index_other_table, other_table)}
representing all relationships to the given table. Indexes are 0-based.
"""
my_field_dict = self._name_to_index(cursor, table_name)
constraints = []
relations = {}
try:
# This should work for MySQL 5.0.
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])
constraints.extend(cursor.fetchall())
except (ProgrammingError, OperationalError):
# Fall back to "SHOW CREATE TABLE", for previous MySQL versions.
# Go through all constraints and save the equal matches.
cursor.execute("SHOW CREATE TABLE %s" % self.connection.ops.quote_name(table_name))
for row in cursor.fetchall():
pos = 0
while True:
match = foreign_key_re.search(row[1], pos)
if match == None:
break
pos = match.end()
constraints.append(match.groups())
for my_fieldname, other_table, other_field in constraints:
other_field_index = self._name_to_index(cursor, other_table)[other_field]
my_field_index = my_field_dict[my_fieldname]
relations[my_field_index] = (other_field_index, other_table)
return relations
def get_indexes(self, cursor, table_name):
"""
Returns a dictionary of fieldname -> infodict for the given table,
where each infodict is in the format:
{'primary_key': boolean representing whether it's the primary key,
'unique': boolean representing whether it's a unique index}
"""
cursor.execute("SHOW INDEX FROM %s" % self.connection.ops.quote_name(table_name))
indexes = {}
for row in cursor.fetchall():
indexes[row[4]] = {'primary_key': (row[2] == 'PRIMARY'), 'unique': not bool(row[1])}
return indexes
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