284 lines
12 KiB
Python
284 lines
12 KiB
Python
import re
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from django.db.backends.base.introspection import (
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BaseDatabaseIntrospection, FieldInfo, TableInfo,
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)
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from django.db.models.indexes import Index
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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:
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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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"""Return a list of table and view 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, type FROM sqlite_master
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WHERE type in ('table', 'view') AND NOT name='sqlite_sequence'
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ORDER BY name""")
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return [TableInfo(row[0], row[1][0]) for row in cursor.fetchall()]
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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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return [
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FieldInfo(
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info['name'],
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info['type'],
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None,
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info['size'],
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None,
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None,
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info['null_ok'],
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info['default'],
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) for info in self._table_info(cursor, table_name)
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]
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def get_sequences(self, cursor, table_name, table_fields=()):
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pk_col = self.get_primary_key_column(cursor, table_name)
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return [{'table': table_name, 'column': pk_col}]
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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 relationships to the given table.
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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(
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"SELECT sql, type FROM sqlite_master "
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"WHERE tbl_name = %s AND type IN ('table', 'view')",
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[table_name]
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)
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create_sql, table_type = cursor.fetchone()
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if table_type == 'view':
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# It might be a view, then no results will be returned
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return relations
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results = create_sql[create_sql.index('(') + 1:create_sql.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_desc in 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(r'references (\S*) ?\(["|]?(.*)["|]?\)', 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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if field_desc.startswith("FOREIGN KEY"):
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# Find name of the target FK field
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m = re.match(r'FOREIGN KEY\s*\(([^\)]*)\).*', field_desc, re.I)
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field_name = m.groups()[0].strip('"')
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else:
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field_name = field_desc.split()[0].strip('"')
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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_desc in 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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other_name = other_desc.split(' ', 1)[0].strip('"')
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if other_name == column:
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relations[field_name] = (other_name, 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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Return a list of (column_name, referenced_table_name, referenced_column_name)
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for all 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(r'"(.*)".*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_primary_key_column(self, cursor, table_name):
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"""Return the column name of the primary key for the given table."""
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# Don't use PRAGMA because that causes issues with some transactions
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cursor.execute(
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"SELECT sql, type FROM sqlite_master "
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"WHERE tbl_name = %s AND type IN ('table', 'view')",
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[table_name]
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)
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row = cursor.fetchone()
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if row is None:
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raise ValueError("Table %s does not exist" % table_name)
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create_sql, table_type = row
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if table_type == 'view':
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# Views don't have a primary key.
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return None
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fields_sql = create_sql[create_sql.index('(') + 1:create_sql.rindex(')')]
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for field_desc in fields_sql.split(','):
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field_desc = field_desc.strip()
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m = re.match(r'(?:(?:["`\[])(.*)(?:["`\]])|(\w+)).*PRIMARY KEY.*', field_desc)
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if m:
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return m.group(1) if m.group(1) else m.group(2)
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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, default_value, pk
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return [{
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'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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'default': field[4],
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'pk': field[5], # undocumented
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} for field in cursor.fetchall()]
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def _get_foreign_key_constraints(self, cursor, table_name):
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constraints = {}
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cursor.execute('PRAGMA foreign_key_list(%s)' % self.connection.ops.quote_name(table_name))
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for row in cursor.fetchall():
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# Remaining on_update/on_delete/match values are of no interest.
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id_, _, table, from_, to = row[:5]
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constraints['fk_%d' % id_] = {
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'columns': [from_],
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'primary_key': False,
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'unique': False,
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'foreign_key': (table, to),
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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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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 index info
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cursor.execute("PRAGMA index_list(%s)" % self.connection.ops.quote_name(table_name))
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for row in cursor.fetchall():
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# Sqlite3 3.8.9+ has 5 columns, however older versions only give 3
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# columns. Discard last 2 columns if there.
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number, index, unique = row[:3]
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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": [],
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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'].append(column)
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# Add type and column orders for indexes
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if constraints[index]['index'] and not constraints[index]['unique']:
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# SQLite doesn't support any index type other than b-tree
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constraints[index]['type'] = Index.suffix
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cursor.execute(
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"SELECT sql FROM sqlite_master "
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"WHERE type='index' AND name=%s" % self.connection.ops.quote_name(index)
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)
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orders = []
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# There would be only 1 row to loop over
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for sql, in cursor.fetchall():
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order_info = sql.split('(')[-1].split(')')[0].split(',')
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orders = ['DESC' if info.endswith('DESC') else 'ASC' for info in order_info]
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constraints[index]['orders'] = orders
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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": [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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constraints.update(self._get_foreign_key_constraints(cursor, table_name))
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return constraints
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