Method and decorator

@api.returns

This decorator guaranties unity of returned value. It will return a RecordSet of specified model based on original returned value:

保证返回值的统一。将返回基于原始返回值指定model的记录集

@api.returns(‘res.partner‘)
def afun(self):
    ...
    return x  # a RecordSet

And if an old API function calls a new API function it will automatically convert it into a list of ids

All decorators inherits from this decorator to upgrade or downgrade the returned value.

用法主要是用来指定返回值的格式，它接受三个参数，第一个为返回值的model，第二个为向下兼容的method，第三个为向上兼容的method

第一个参数如果是对象本身，以‘self‘,如果是其他对象，则写其他对象名如：@api.returns(‘ir.ui.view‘)

@api.one

This decorator loops automatically on Records of RecordSet for you. Self is redefined as current record:

one装饰符自动遍历记录集，把self重新定义成当前记录。【对于v7版本中类似于 def funct(self,cr,uid,ids,context)的方法可以用api.one装饰器改用v8写法。】

@api.one
def afun(self):
    self.name = ‘toto‘

@api.multi

Self will be the current RecordSet without iteration. It is the default behavior:

self就是当前记录集。不需要遍历

@api.multi
def afun(self):
    len(self)

@api.model

This decorator will convert old API calls to decorated function to new API signature. It allows to be polite when migrating code.

该装饰会将旧的API函数转换成带有装饰符的新API函数符号，使得代码可以平滑迁移【即适用于v7中类似于 def funct(self,cr,uid,args,context)的方法。 】 

1 @api.model
　　def afun(self):
    　　pass

langs = fields.Selection(string="Lang",selection="_get_lang") 

＠api.model
def _get_lang(self):
    langs = self.env[‘res.lang‘].search([])
    return [(lang.code,lang.name) for lang in langs]

@api.constrains

This decorator will ensure that decorated function will be called on create, write, unlink operation. If a constraint is met the function should raise a openerp.exceptions.Warning with appropriate message.

该装饰确保被修饰的函数在create, write, unlink时被调用。当约束条件满足时，函数应该raise 相应的异常警告消息

　　＠api.constrains(‘age‘)

　　def_check_age(self):

　　　　if self.age<16:

　　　　raise ValueError(_(‘Age must be older than 16‘))

@api.depends

This decorator will trigger the call to the decorated function if any of the fields specified in the decorator is altered by ORM or changed in the form:

依赖的任一字段变化时（ORM or Form），触发该函数执行

@api.depends(‘name‘, ‘an_other_field‘)
def afun(self):
    pass

@api.onchange

This decorator will trigger the call to the decorated function if any of the fields specified in the decorator is changed in the form:

@api.onchange(‘fieldx‘)
def do_stuff(self):
   if self.fieldx == x:
      self.fieldy = ‘toto‘

In previous sample self corresponds to the record currently edited on the form. When in on_change context all work is done in the cache. So you can alter RecordSet inside your function without being worried about altering database. That’s the main difference with @api.depends

At function return, differences between the cache and the RecordSet will be returned to the form.

例子中self是指form中的记录，当在on_change上下文时，所有的工作都是在缓存中进行，所以你可以在函数中直接修改记录集而不用担心会修改数据库， 这是和depends的最大区别。函数返回时将缓存和记录集中的差异返回给form.

@api.noguess

This decorator prevent new API decorators to alter the output of a method