python类source_expressions()的实例源码

def __init__(self, *expressions, **extra):
        output_field = extra.pop('output_field', None)
        super(Func, self).__init__(output_field=output_field)
        self.source_expressions = self._parse_expressions(*expressions)
        self.extra = extra

def __repr__(self):
        args = self.arg_joiner.join(str(arg) for arg in self.source_expressions)
        extra = ', '.join(str(key) + '=' + str(val) for key, val in self.extra.items())
        if extra:
            return "{}({}, {})".format(self.__class__.__name__, args, extra)
        return "{}({})".format(self.__class__.__name__, args)

def set_source_expressions(self, exprs):
        self.source_expressions = exprs

def resolve_expression(self, query=None, allow_joins=True, reuse=None, summarize=False, for_save=False):
        c = self.copy()
        c.is_summary = summarize
        for pos, arg in enumerate(c.source_expressions):
            c.source_expressions[pos] = arg.resolve_expression(query, allow_joins, reuse, summarize, for_save)
        return c

def as_sql(self, compiler, connection, function=None, template=None):
        connection.ops.check_expression_support(self)
        sql_parts = []
        params = []
        for arg in self.source_expressions:
            arg_sql, arg_params = compiler.compile(arg)
            sql_parts.append(arg_sql)
            params.extend(arg_params)
        if function is None:
            self.extra['function'] = self.extra.get('function', self.function)
        else:
            self.extra['function'] = function
        self.extra['expressions'] = self.extra['field'] = self.arg_joiner.join(sql_parts)
        template = template or self.extra.get('template', self.template)
        return template % self.extra, params