Traitlet Widgets
Examples
Model View
For a given model:
from traitlets import HasTraits, Integer, Unicode
class Model(HasTraits):
age = Integer(min=0)
name = Unicode()We can create a view using model_view
from traitlet_widgets import model_view
model = Model()
view = model_view(model)which gives
UI Customisation
The UI can be customised through the use of TraitType.tag() or a custom transformer function.
Metadata
Any tag set on a trait will be trialed as a widget attribute. If the attribute does not exist on the widget then it will not be set. For example:
from traitlets import HasTraits, Integer, Unicode
from traitlet_widgets import model_view
class Model(HasTraits):
age = Integer(min=0)
name = Unicode().tag(description="A girl has no name")
model = Model()
model_view(model)
The same metadata that can be provided using tags can also be provided through a hierarchical metadata dictionary:
model_view(model, metadata={"name": {"description": "Model name meta"}})This may be desired if it is important to hide UI details from the model.
Variants
It is possible to override the variant used for a particular trait, provided it is compatible with the underlying trait:
from traitlets import HasTraits, Integer, Unicode
from traitlet_widgets import model_view
class Model(HasTraits):
age = Integer(min=0, max=10)
name = Unicode()
model_view(Model())
Let's create a bounded integer text view for the age field:
from traitlets import HasTraits, Integer, Unicode
from traitlet_widgets import model_view
import ipywidgets as widgets
class Model(HasTraits):
age = Integer(min=0, max=10).tag(variant=widgets.BoundedIntText)
name = Unicode()
model_view(Model())
Advanced Usage
To further control how a view is generated from a model, you can subclass the view factory. For example, given this model
from traitlets import HasTraits, Integer, Unicode
from traitlet_widgets import model_view
import ipywidgets as widgets
class Model(HasTraits):
age = Integer(min=0, max=10).tag(variant=widgets.BoundedIntText)
name = Unicode()
model_view(Model())we can create a custom view factory:
from traitlet_widgets import ViewFactory
class CustomFactory(ViewFactory):
def create_trait_view(self, trait, ctx):
default_widget = super().create_trait_view(trait, ctx)
if ctx.name == "name":
default_widget.description = "A girl has no name"
default_widget.style = {"description_width": "initial"}
return default_widget
f = CustomFactory()
f.create_root_view(Model())
Adding custom widgets
With the trait_view_variants decorator, it is possible to register custom view
variants for a particular trait type, for example:
from traitlet_widgets import trait_view_variants
import ipywidgets as widgets
import traitlets
@trait_view_variants(traitlets.Bool)
def bool_view_factory(trait, ctx):
yield widgets.ToggleButton, ctx.metadata
...But sometimes you might wish to forgo the metadata-driven UI, and directly
specify the factory and its arguments. For this, you can use the factory metadata
field:
from traitlets import HasTraits, Integer, Unicode
from traitlet_widgets import model_view
import ipywidgets as widgets
class Model(HasTraits):
age = Integer(min=0, max=10)
name = Unicode()
def play_factory(trait, ctx):
return widgets.Play, {
"min": trait.get("min", 0),
"max": trait.get("max", 100),
**ctx.metadata,
}
model_view(Model(), metadata={"age": {"factory": play_factory}})Further Customisation
Although this library is driven by metadata, it is possible to modify this behaviour by overriding the appropriate methods on the view factory. These methods govern the trait discovery, view creation, and trait filtering.
