How to use the trytond.transaction.Transaction function in trytond

def test_0030_test_render_iteration(self):
        """
        Test render iteration
        """
        Iteration = POOL.get('project.iteration')

        with Transaction().start(DB_NAME, USER, context=CONTEXT):
            self.create_defaults()
            app = self.get_app(DEBUG=True)
            with Transaction().set_context(company=self.company.id):
                work1, = self.Work.create([{
                    'name': 'ABC Project',
                    'company': self.company.id,
                }])
                project, = self.Project.create([{
                    'work': work1.id,
                    'type': 'project',
                    'state': 'opened',
                    'sequence': 1,
                }])
                self.assert_(project)

                work2, = self.Work.create([{
                    'name': 'User Story',
                    'company': self.company.id,
                }])

def mkcol(self, uri):
        dbname, dburi = self._get_dburi(uri)
        if not dbname or not dburi:
            raise DAV_Forbidden
        pool = Pool(Transaction().cursor.database_name)
        Collection = pool.get('webdav.collection')
        try:
            res = Collection.mkcol(dburi, cache=CACHE)
            Transaction().cursor.commit()
        except (DAV_Error, DAV_NotFound, DAV_Secret, DAV_Forbidden), exception:
            self._log_exception(exception)
            Transaction().cursor.rollback()
            raise
        except Exception, exception:
            self._log_exception(exception)
            Transaction().cursor.rollback()
            raise DAV_Error(500)
        return res

def add_fk(self, column_name, reference, on_delete=None):
        if on_delete is not None:
            on_delete = on_delete.upper()
        else:
            on_delete = 'SET NULL'

        cursor = Transaction().connection.cursor()
        name = self.convert_name(self.table_name + '_' + column_name + '_fkey')
        if name in self._constraints:
            if self._fk_deltypes.get(column_name) != on_delete:
                self.drop_fk(column_name)
                add = True
            else:
                add = False
        else:
            add = True
        if add:
            cursor.execute('ALTER TABLE "' + self.table_name + '" '
                'ADD CONSTRAINT "' + name + '" '
                'FOREIGN KEY ("' + column_name + '") '
                'REFERENCES "' + reference + '" '
                'ON DELETE ' + on_delete)
        self._update_definitions(constraints=True)

def _get_cache(self):
        transaction = Transaction()
        dbname = transaction.database.name
        lower = self._transaction_lower.get(dbname, self._default_lower)
        if (transaction in self._reset
                or transaction.started_at < lower):
            try:
                return self._transaction_cache[transaction]
            except KeyError:
                cache = self._database_cache.default_factory()
                self._transaction_cache[transaction] = cache
                return cache
        else:
            return self._database_cache[dbname]

def get_action_id(cls, action_id):
        pool = Pool()
        with Transaction().set_context(active_test=False):
            if cls.search([
                        ('id', '=', action_id),
                        ]):
                return action_id
            for action_type in (
                    'ir.action.report',
                    'ir.action.act_window',
                    'ir.action.wizard',
                    'ir.action.url',
                    ):
                Action = pool.get(action_type)
                actions = Action.search([
                    ('id', '=', action_id),
                    ])
                if actions:
                    action, = actions

def _domain_column(self, operator, column, key=None):
        database = Transaction().database
        column = database.json_get(
            super()._domain_column(operator, column), key)
        if operator.endswith('like'):
            column = Cast(column, database.sql_type('VARCHAR').base)
            if self.search_unaccented and operator.endswith('ilike'):
                column = database.unaccent(column)
        return column

field = cls._fields[fname]
                if not hasattr(field, 'set'):
                    if (not getattr(field, 'translate', False)
                            or store_translation):
                        columns.append(Column(table, fname))
                        update_values.append(field.sql_format(value))

            for sub_ids in grouped_slice(ids):
                red_sql = reduce_ids(table.id, sub_ids)
                try:
                    cursor.execute(*table.update(columns, update_values,
                            where=red_sql))
                except backend.DatabaseIntegrityError as exception:
                    transaction = Transaction()
                    with Transaction().new_transaction(), \
                            Transaction().set_context(_check_access=False):
                        cls.__raise_integrity_error(
                            exception, values, list(values.keys()),
                            transaction=transaction)
                    raise

            for fname, value in values.items():
                field = cls._fields[fname]
                if (getattr(field, 'translate', False)
                        and not hasattr(field, 'set')):
                    Translation.set_ids(
                        '%s,%s' % (cls.__name__, fname), 'model',
                        transaction.language, ids, [value] * len(ids))
                if hasattr(field, 'set'):
                    fields_to_set.setdefault(fname, []).extend((ids, value))

            field_names = list(values.keys())

def write(cls, reports, values, *args):
        context = Transaction().context
        if 'module' in context:
            actions = iter((reports, values) + args)
            args = []
            for reports, values in zip(actions, actions):
                values = values.copy()
                values['module'] = context['module']
                args.extend((reports, values))
            reports, values = args[:2]
            args = args[2:]
        super(ActionReport, cls).write(reports, values, *args)

def _update_definitions(self, columns=None, indexes=None):
        if columns is None and indexes is None:
            columns = indexes = True
        cursor = Transaction().connection.cursor()
        # Fetch columns definitions from the table
        if columns:
            cursor.execute('PRAGMA table_info("' + self.table_name + '")')
            self._columns = {}
            for _, column, type_, notnull, hasdef, _ in cursor.fetchall():
                column = re.sub(r'^\"|\"$', '', column)
                match = re.match(r'(\w+)(\((.*?)\))?', type_)
                if match:
                    typname = match.group(1).upper()
                    size = match.group(3) and int(match.group(3)) or 0
                else:
                    typname = type_.upper()
                    size = -1
                self._columns[column] = {
                    'notnull': notnull,
                    'hasdef': hasdef,

def not_null_action(self, column_name, action='add'):
        if not self.column_exist(column_name):
            return

        with Transaction().connection.cursor() as cursor:
            if action == 'add':
                if self._columns[column_name]['notnull']:
                    return
                cursor.execute('SELECT id FROM "%s" '
                    'WHERE "%s" IS NULL'
                    % (self.table_name, column_name))
                if not cursor.rowcount:
                    cursor.execute('ALTER TABLE "' + self.table_name + '" '
                        'ALTER COLUMN "' + column_name + '" SET NOT NULL')
                    self._update_definitions(columns=True)
                else:
                    logger.warning(
                        'Unable to set column %s '
                        'of table %s not null !\n'
                        'Try to re-run: '
                        'trytond.py --update=module\n'