import re
from django.db.backends import BaseDatabaseIntrospection, FieldInfo
field_size_re = re.compile(r'^\s*(?:var)?char\s*\(\s*(\d+)\s*\)\s*$')
def get_field_size(name):
""" Extract the size number from a "varchar(11)" type name """
m = field_size_re.search(name)
return int(m.group(1)) if m else None
# This light wrapper "fakes" a dictionary interface, because some SQLite data
# types include variables in them -- e.g. "varchar(30)" -- and can't be matched
# as a simple dictionary lookup.
class FlexibleFieldLookupDict(object):
# Maps SQL types to Django Field types. Some of the SQL types have multiple
# entries here because SQLite allows for anything and doesn't normalize the
# field type; it uses whatever was given.
base_data_types_reverse = {
'bool': 'BooleanField',
'boolean': 'BooleanField',
'smallint': 'SmallIntegerField',
'smallint unsigned': 'PositiveSmallIntegerField',
'smallinteger': 'SmallIntegerField',
'int': 'IntegerField',
'integer': 'IntegerField',
'bigint': 'BigIntegerField',
'integer unsigned': 'PositiveIntegerField',
'decimal': 'DecimalField',
'real': 'FloatField',
'text': 'TextField',
'char': 'CharField',
'blob': 'BinaryField',
'date': 'DateField',
'datetime': 'DateTimeField',
'time': 'TimeField',
}
def __getitem__(self, key):
key = key.lower()
try:
return self.base_data_types_reverse[key]
except KeyError:
size = get_field_size(key)
if size is not None:
return ('CharField', {'max_length': size})
raise KeyError
class DatabaseIntrospection(BaseDatabaseIntrospection):
data_types_reverse = FlexibleFieldLookupDict()
def get_table_list(self, cursor):
"Returns a list of table names in the current database."
# Skip the sqlite_sequence system table used for autoincrement key
# generation.
cursor.execute("""
SELECT name FROM sqlite_master
WHERE type='table' AND NOT name='sqlite_sequence'
ORDER BY name""")
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."
return [FieldInfo(info['name'], info['type'], None, info['size'], None, None,
info['null_ok']) for info in self._table_info(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.
"""
# Dictionary of relations to return
relations = {}
# Schema for this table
cursor.execute("SELECT sql FROM sqlite_master WHERE tbl_name = %s AND type = %s", [table_name, "table"])
results = cursor.fetchone()[0].strip()
results = results[results.index('(')+1:results.rindex(')')]
# Walk through and look for references to other tables. SQLite doesn't
# really have enforced references, but since it echoes out the SQL used
# to create the table we can look for REFERENCES statements used there.
for field_index, field_desc in enumerate(results.split(',')):
field_desc = field_desc.strip()
if field_desc.startswith("UNIQUE"):
continue
m = re.search('references (.*) \(["|](.*)["|]\)', field_desc, re.I)
if not m:
continue
table, column = [s.strip('"') for s in m.groups()]
cursor.execute("SELECT sql FROM sqlite_master WHERE tbl_name = %s", [table])
result = cursor.fetchall()[0]
other_table_results = result[0].strip()
li, ri = other_table_results.index('('), other_table_results.rindex(')')
other_table_results = other_table_results[li+1:ri]
for other_index, other_desc in enumerate(other_table_results.split(',')):
other_desc = other_desc.strip()
if other_desc.startswith('UNIQUE'):
continue
name = other_desc.split(' ', 1)[0].strip('"')
if name == column:
relations[field_index] = (other_index, table)
break
return relations
def get_key_columns(self, cursor, table_name):
"""
Returns a list of (column_name, referenced_table_name, referenced_column_name) for all
key columns in given table.
"""
key_columns = []
# Schema for this table
cursor.execute("SELECT sql FROM sqlite_master WHERE tbl_name = %s AND type = %s", [table_name, "table"])
results = cursor.fetchone()[0].strip()
results = results[results.index('(')+1:results.rindex(')')]
# Walk through and look for references to other tables. SQLite doesn't
# really have enforced references, but since it echoes out the SQL used
# to create the table we can look for REFERENCES statements used there.
for field_index, field_desc in enumerate(results.split(',')):
field_desc = field_desc.strip()
if field_desc.startswith("UNIQUE"):
continue
m = re.search('"(.*)".*references (.*) \(["|](.*)["|]\)', field_desc, re.I)
if not m:
continue
# This will append (column_name, referenced_table_name, referenced_column_name) to key_columns
key_columns.append(tuple([s.strip('"') for s in m.groups()]))
return key_columns
def get_indexes(self, cursor, table_name):
indexes = {}
for info in self._table_info(cursor, table_name):
if info['pk'] != 0:
indexes[info['name']] = {'primary_key': True,
'unique': False}
cursor.execute('PRAGMA index_list(%s)' % self.connection.ops.quote_name(table_name))
# seq, name, unique
for index, unique in [(field[1], field[2]) for field in cursor.fetchall()]:
cursor.execute('PRAGMA index_info(%s)' % self.connection.ops.quote_name(index))
info = cursor.fetchall()
# Skip indexes across multiple fields
if len(info) != 1:
continue
name = info[0][2] # seqno, cid, name
indexes[name] = {'primary_key': False,
'unique': unique}
return indexes
def get_primary_key_column(self, cursor, table_name):
"""
Get the column name of the primary key for the given table.
"""
# Don't use PRAGMA because that causes issues with some transactions
cursor.execute("SELECT sql FROM sqlite_master WHERE tbl_name = %s AND type = %s", [table_name, "table"])
results = cursor.fetchone()[0].strip()
results = results[results.index('(')+1:results.rindex(')')]
for field_desc in results.split(','):
field_desc = field_desc.strip()
m = re.search('"(.*)".*PRIMARY KEY$', field_desc)
if m:
return m.groups()[0]
return None
def _table_info(self, cursor, name):
cursor.execute('PRAGMA table_info(%s)' % self.connection.ops.quote_name(name))
# cid, name, type, notnull, dflt_value, pk
return [{'name': field[1],
'type': field[2],
'size': get_field_size(field[2]),
'null_ok': not field[3],
'pk': field[5] # undocumented
} for field in cursor.fetchall()]