database.py

# -*- python -*-
# -*- coding: utf-8 -*-
# Started 24/05/2011 by Seblu <seblu@seblu.net>

'''
Database stuff
'''

import os
import sqlite3
import installsystems.tools as istools
import installsystems.template as istemplate
from installsystems.tarball import Tarball
from installsystems.printer import *

class Database(object):
    '''
    Abstract repo database stuff
    It needs to be local cause of sqlite3 which need to open a file
    '''

    db_format = "1"

    @classmethod
    def create(cls, path):
        arrow("Creating repository database")
        # check locality
        if not istools.isfile(path):
            raise Exception("Database creation must be local")
        path = os.path.abspath(path)
        if os.path.exists(path):
            raise Exception("Database already exists. Remove it before")
        try:
            conn = sqlite3.connect(path, isolation_level=None)
            conn.execute("PRAGMA foreign_keys = ON")
            conn.executescript(istemplate.createdb)
            conn.commit()
            conn.close()
        except Exception as e:
            raise Exception("Create database failed: %s" % e)
        return cls(path)

    def __init__(self, path):
        # check locality
        if not istools.isfile(path):
            raise Exception("Database must be local")
        self.path = os.path.abspath(path)
        if not os.path.exists(self.path):
            raise Exception("Database not exists")
        self.conn = sqlite3.connect(self.path, isolation_level=None)
        self.conn.execute("PRAGMA foreign_keys = ON")

    def begin(self):
        '''
        Start a db transaction
        '''
        self.conn.execute("BEGIN TRANSACTION")

    def commit(self):
        '''
        Commit current db transaction
        '''
        self.conn.execute("COMMIT TRANSACTION")


    def ask(self, sql, args=()):
        '''
        Ask question to db
        '''
        return self.conn.execute(sql, args)