Odoo13迁移至Odoo15遇AttributeError：找不到mako_template_env属性

函数在Odoo 13中运行正常，但迁移至Odoo 15时抛出以下错误：

AttributeError: module 'odoo.addons.mail.models.mail_template' has no attribute 'mako_template_env'

原函数代码如下：

def render_doc(self, doctype):
        types = {'cert': 'Certificate', 'pol_doc': 'Policy Document',
                 'guarantee_cert': 'Guarantee Policy Certificate'}
        if doctype not in types.keys():
            raise UserError(_('Document must be of type cert or pol_doc'))

        prod_doc_ids = self.policy_id.product_id.product_doc_ids
        doc = prod_doc_ids.filtered(
            lambda c: c.doc_type == doctype) if prod_doc_ids else False
        if doc:
            body = doc.body
        else:
            body = f"<p><strong>{types[doctype]}</strong> is not yet \
                setup for <strong>{self.policy_id.product_id.name}.</strong>\
                Please contact the system administrator.</p>"
        return mail_template.mako_template_env.from_string(body).render({'object': self})

Odoo 15中已移除mail_template模块级别的mako_template_env属性，需改用官方提供的模板渲染方式，以下是两种可行方案：

方案一：使用官方工具函数（推荐） #

直接调用odoo.tools.mail.render_template函数，该函数会自动处理Mako模板渲染，并将当前记录作为object传入模板，与原逻辑完全匹配：

from odoo.tools.mail import render_template

def render_doc(self, doctype):
        types = {'cert': 'Certificate', 'pol_doc': 'Policy Document',
                 'guarantee_cert': 'Guarantee Policy Certificate'}
        if doctype not in types.keys():
            raise UserError(_('Document must be of type cert or pol_doc'))

        prod_doc_ids = self.policy_id.product_id.product_doc_ids
        doc = prod_doc_ids.filtered(
            lambda c: c.doc_type == doctype) if prod_doc_ids else False
        if doc:
            body = doc.body
        else:
            body = f"<p><strong>{types[doctype]}</strong> is not yet \
                setup for <strong>{self.policy_id.product_id.name}.</strong>\
                Please contact the system administrator.</p>"
        # 替换原mako环境调用为官方渲染函数
        return render_template(body, self._name, self.id)

方案二：获取官方维护的Mako环境 #

如果需要自定义渲染上下文，可通过邮件模板模型的_get_mako_env方法获取官方Mako环境：

def render_doc(self, doctype):
        types = {'cert': 'Certificate', 'pol_doc': 'Policy Document',
                 'guarantee_cert': 'Guarantee Policy Certificate'}
        if doctype not in types.keys():
            raise UserError(_('Document must be of type cert or pol_doc'))

        prod_doc_ids = self.policy_id.product_id.product_doc_ids
        doc = prod_doc_ids.filtered(
            lambda c: c.doc_type == doctype) if prod_doc_ids else False
        if doc:
            body = doc.body
        else:
            body = f"<p><strong>{types[doctype]}</strong> is not yet \
                setup for <strong>{self.policy_id.product_id.name}.</strong>\
                Please contact the system administrator.</p>"
        # 获取官方Mako环境
        mako_env = self.env['mail.template']._get_mako_env()
        return mako_env.from_string(body).render({'object': self})

内容的提问来源于stack exchange，提问作者MarkHenri