因此,花了我很多时间才发现这个问题,但是 ,因此它会不断侦听是否发生更改,并且应该对其他列表进行更新。 在这种情况下:
@pn.depends(continent.param.value, watch=True)
整个例子:
_countries = {
'Africa': ['Ghana', 'Togo', 'South Africa'],
'Asia' : ['China', 'Thailand', 'Japan'],
'Europe': ['Austria', 'Bulgaria', 'Greece']
}
continent = pn.widgets.Select(
value='Asia',
options=['Africa', 'Asia', 'Europe']
)
country = pn.widgets.Select(
value=_countries[continent.value][0],
options=_countries[continent.value]
)
@pn.depends(continent.param.value, watch=True)
def _update_countries(continent):
countries = _countries[continent]
country.options = countries
country.value = countries[0]
pn.Row(continent, country)
此页面上的GoogleMapViewer示例为我指明了正确的方向:选择器在另一个选择器更改后更新
相同的答案,但以类的形式:
class GoogleMapViewer(param.Parameterized):
continent = param.Selector(default='Asia', objects=['Africa', 'Asia', 'Europe'])
country = param.Selector(default='China', objects=['China', 'Thailand', 'Japan'])
_countries = {'Africa': ['Ghana', 'Togo', 'South Africa'],
'Asia' : ['China', 'Thailand', 'Japan'],
'Europe': ['Austria', 'Bulgaria', 'Greece']}
@param.depends('continent', watch=True)
def _update_countries(self):
countries = self._countries[self.continent]
self.param['country'].objects = countries
self.country = countries[0]
viewer = GoogleMapViewer(name='Google Map Viewer')
pn.Row(viewer.param)