onchange装饰器具体是如何触发的？

[dennis888]

1.示例
from odoo import models, fields,api
class AModel(models.Model):
_name = 'a.model.name'
field1 = fields.Char()
field2 = fields.Integer(string="an other field")

@api.onchange('field1', 'field2') # 当这两个字段值改变时调用该函数
def check_change(self):
if self.field1 < self.field2:
self.field3 = True

2.api.py
def onchange(*args):
""" Return a decorator to decorate an onchange method for given fields.
Each argument must be a field name """
return attrsetter('_onchange', args)

def attrsetter(attr, value):
""" Return a function that sets attr on its argument and returns it. """
return lambda method: setattr(method, attr, value) or method

'''
The following attributes are used, and reflected on wrapping methods:

• method._onchange: set by @onchange, specifies onchange fields
• method.clear_cache: set by @ormcache, used to clear the cache

On wrapping method only:

• method._api: decorator function, used for re-applying decorator
• method._orig: original method
  '''

WRAPPED_ATTRS = ('module', 'name', 'doc', '_constrains',
'_depends', '_onchange', '_returns', 'clear_cache')

INHERITED_ATTRS = ('_returns',)

3. 问题：
   请问当'field1', 'field2'字段值发生变化时，是如何触发调用装饰器函数的？_onchange 是fields类的一个内部方法吗？可是在api,fields和models里都没找到哦，哪位大牛能帮解答一下？谢谢

[静静]

在js 里面找吧。。。