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