widget

Provide a base class for all Bokeh widget models.

In addition to different kinds of plots, various kinds of UI controls (e.g. sliders, buttons, inputs, etc.) can be included in Bokeh documents. These widgets can be used in conjunction with CustomJS callbacks that execute in the browser, or with python callbacks that execute on a Bokeh server.

class Widget(*args: Any, id: ID | None = None, **kwargs: Any)

Bases: LayoutDOM

A base class for all interactive widget types.

Note

This is an abstract base class used to help organize the hierarchy of Bokeh model types. It is not useful to instantiate on its own.

JSON Prototype

{
  "align": "auto", 
  "aspect_ratio": null, 
  "context_menu": null, 
  "css_classes": [], 
  "css_variables": {
    "type": "map"
  }, 
  "disabled": false, 
  "elements": [], 
  "flow_mode": "block", 
  "height": null, 
  "height_policy": "auto", 
  "id": "p63850", 
  "js_event_callbacks": {
    "type": "map"
  }, 
  "js_property_callbacks": {
    "type": "map"
  }, 
  "margin": 5, 
  "max_height": null, 
  "max_width": null, 
  "min_height": null, 
  "min_width": null, 
  "name": null, 
  "resizable": false, 
  "sizing_mode": null, 
  "styles": {
    "type": "map"
  }, 
  "stylesheets": [], 
  "subscribed_events": {
    "type": "set"
  }, 
  "syncable": true, 
  "tags": [], 
  "visible": true, 
  "width": null, 
  "width_policy": "auto"
}

align = 'auto'

Type:

Either(Auto, Enum(Align), Tuple(Enum(Align), Enum(Align)))

The alignment point within the parent container.

This property is useful only if this component is a child element of a layout (e.g. a grid). Self alignment can be overridden by the parent container (e.g. grid track align).

aspect_ratio = None

Type:

Either(Null, Auto, Float)

Describes the proportional relationship between component’s width and height.

This works if any of component’s dimensions are flexible in size. If set to a number, width / height = aspect_ratio relationship will be maintained. Otherwise, if set to "auto", component’s preferred width and height will be used to determine the aspect (if not set, no aspect will be preserved).

context_menu = None

Type:

Nullable(Instance(Menu))

A menu to display when user right clicks on the component.

Note

Use shift key when right clicking to display the native context menu.

css_classes = []

Type:

List

A list of additional CSS classes to add to the underlying DOM element.

css_variables = {}

Type:

Dict(String, Instance(Node))

Allows to define dynamically computed CSS variables.

This can be used, for example, to coordinate positioning and styling between canvas’ renderers and/or visuals and HTML-based UI elements.

Variables defined here are equivalent to setting the same variables under :host { ... } in a CSS stylesheet.

Note

This property is experimental and may change at any point.

disabled = False

Type:

Bool

Whether the widget will be disabled when rendered.

If True, the widget will be greyed-out and not responsive to UI events.

elements = []

Type:

List

A collection of DOM-based UI elements attached to this pane.

This can include floating elements like tooltips, allowing to establish a parent-child relationship between this and other UI elements.

flow_mode = 'block'

Type:

Enum(FlowMode)

Defines whether the layout will flow in the block or inline dimension.

height = None

Type:

Nullable(NonNegative)

The height of the component (in pixels).

This can be either fixed or preferred height, depending on height sizing policy.

height_policy = 'auto'

Type:

Either(Auto, Enum(SizingPolicy))

Describes how the component should maintain its height.

"auto"

Use component’s preferred sizing policy.

"fixed"

Use exactly height pixels. Component will overflow if it can’t fit in the available vertical space.

"fit"

Use component’s preferred height (if set) and allow to fit into the available vertical space within the minimum and maximum height bounds (if set). Component’s height neither will be aggressively minimized nor maximized.

"min"

Use as little vertical space as possible, not less than the minimum height (if set). The starting point is the preferred height (if set). The height of the component may shrink or grow depending on the parent layout, aspect management and other factors.

"max"

Use as much vertical space as possible, not more than the maximum height (if set). The starting point is the preferred height (if set). The height of the component may shrink or grow depending on the parent layout, aspect management and other factors.

Note

This is an experimental feature and may change in future. Use it at your own discretion. Prefer using sizing_mode if this level of control isn’t strictly necessary.

margin = 5

Type:

Nullable(Either(Int, Tuple(Int, Int), Tuple(Int, Int, Int, Int)))

Allows to create additional space around the component. The values in the tuple are ordered as follows - Margin-Top, Margin-Right, Margin-Bottom and Margin-Left, similar to CSS standards. Negative margin values may be used to shrink the space from any direction.

max_height = None

Type:

Nullable(NonNegative)

Maximal height of the component (in pixels) if height is adjustable.

max_width = None

Type:

Nullable(NonNegative)

Maximal width of the component (in pixels) if width is adjustable.

min_height = None

Type:

Nullable(NonNegative)

Minimal height of the component (in pixels) if height is adjustable.

min_width = None

Type:

Nullable(NonNegative)

Minimal width of the component (in pixels) if width is adjustable.

name = None

Type:

Nullable(String)

An arbitrary, user-supplied name for this model.

This name can be useful when querying the document to retrieve specific Bokeh models.

>>> plot.circle([1,2,3], [4,5,6], name="temp")
>>> plot.select(name="temp")
[GlyphRenderer(id='399d53f5-73e9-44d9-9527-544b761c7705', ...)]

Note

No uniqueness guarantees or other conditions are enforced on any names that are provided, nor is the name used directly by Bokeh for any reason.

resizable = False

Type:

Either(Bool, Enum(Dimensions))

Whether the layout is interactively resizable, and if so in which dimensions.

sizing_mode = None

Type:

Nullable(Enum(SizingMode))

How the component should size itself.

This is a high-level setting for maintaining width and height of the component. To gain more fine grained control over sizing, use width_policy, height_policy and aspect_ratio instead (those take precedence over sizing_mode).

Possible scenarios:

"inherit"

The sizing mode is inherited from the parent layout. If there is no parent layout (or parent is not a layout), then this value is treated as if no value for sizing_mode was provided.

"fixed"

Component is not responsive. It will retain its original width and height regardless of any subsequent browser window resize events.

"stretch_width"

Component will responsively resize to stretch to the available width, without maintaining any aspect ratio. The height of the component depends on the type of the component and may be fixed or fit to component’s contents.

"stretch_height"

Component will responsively resize to stretch to the available height, without maintaining any aspect ratio. The width of the component depends on the type of the component and may be fixed or fit to component’s contents.

"stretch_both"

Component is completely responsive, independently in width and height, and will occupy all the available horizontal and vertical space, even if this changes the aspect ratio of the component.

"scale_width"

Component will responsively resize to stretch to the available width, while maintaining the original or provided aspect ratio.

"scale_height"

Component will responsively resize to stretch to the available height, while maintaining the original or provided aspect ratio.

"scale_both"

Component will responsively resize to both the available width and height, while maintaining the original or provided aspect ratio.

styles = {}

Type:

Either(Dict(String, Nullable(String)), Instance(Styles))

Inline CSS styles applied to the underlying DOM element.

stylesheets = []

Type:

List

Additional style-sheets to use for the underlying DOM element.

Note that all bokeh’s components use shadow DOM, thus any included style sheets must reflect that, e.g. use :host CSS pseudo selector to access the root DOM element.

syncable = True

Type:

Bool

Indicates whether this model should be synchronized back to a Bokeh server when updated in a web browser. Setting to False may be useful to reduce network traffic when dealing with frequently updated objects whose updated values we don’t need.

Note

Setting this property to False will prevent any on_change() callbacks on this object from triggering. However, any JS-side callbacks will still work.

tags = []

Type:

List

An optional list of arbitrary, user-supplied values to attach to this model.

This data can be useful when querying the document to retrieve specific Bokeh models:

>>> r = plot.circle([1,2,3], [4,5,6])
>>> r.tags = ["foo", 10]
>>> plot.select(tags=['foo', 10])
[GlyphRenderer(id='1de4c3df-a83d-480a-899b-fb263d3d5dd9', ...)]

Or simply a convenient way to attach any necessary metadata to a model that can be accessed by CustomJS callbacks, etc.

Note

No uniqueness guarantees or other conditions are enforced on any tags that are provided, nor are the tags used directly by Bokeh for any reason.

visible = True

Type:

Bool

Whether the component should be displayed on screen.

width = None

Type:

Nullable(NonNegative)

The width of the component (in pixels).

This can be either fixed or preferred width, depending on width sizing policy.

width_policy = 'auto'

Type:

Either(Auto, Enum(SizingPolicy))

Describes how the component should maintain its width.

"auto"

Use component’s preferred sizing policy.

"fixed"

Use exactly width pixels. Component will overflow if it can’t fit in the available horizontal space.

"fit"

Use component’s preferred width (if set) and allow it to fit into the available horizontal space within the minimum and maximum width bounds (if set). Component’s width neither will be aggressively minimized nor maximized.

"min"

Use as little horizontal space as possible, not less than the minimum width (if set). The starting point is the preferred width (if set). The width of the component may shrink or grow depending on the parent layout, aspect management and other factors.

"max"

Use as much horizontal space as possible, not more than the maximum width (if set). The starting point is the preferred width (if set). The width of the component may shrink or grow depending on the parent layout, aspect management and other factors.

Note

This is an experimental feature and may change in future. Use it at your own discretion. Prefer using sizing_mode if this level of control isn’t strictly necessary.

apply_theme(property_values: dict[str, Any]) → None

Apply a set of theme values which will be used rather than defaults, but will not override application-set values.

The passed-in dictionary may be kept around as-is and shared with other instances to save memory (so neither the caller nor the HasProps instance should modify it).

Parameters:

property_values (dict) – theme values to use in place of defaults

Returns:

None

clone(**overrides: Any) → Self

Duplicate a HasProps object.

This creates a shallow clone of the original model, i.e. any mutable containers or child models will not be duplicated. Allows to override particular properties while cloning.

classmethod dataspecs() → dict[str, DataSpec]

Collect the names of all DataSpec properties on this class.

This method always traverses the class hierarchy and includes properties defined on any parent classes.

Returns:

names of DataSpec properties

Return type:

set[str]

classmethod descriptors() → list[PropertyDescriptor[Any]]

List of property descriptors in the order of definition.

destroy() → None

Clean up references to the document and property

equals(other: HasProps) → bool

Structural equality of models.

Parameters:

other (HasProps) – the other instance to compare to

Returns:

True, if properties are structurally equal, otherwise False

js_link(attr: str, other: Model, other_attr: str, attr_selector: int | str | None = None) → None

Link two Bokeh model properties using JavaScript.

This is a convenience method that simplifies adding a CustomJS callback to update one Bokeh model property whenever another changes value.

Parameters:

• attr (str) – The name of a Bokeh property on this model

• other (Model) – A Bokeh model to link to self.attr

• other_attr (str) – The property on other to link together

• attr_selector (Union[int, str]) – The index to link an item in a subscriptable attr

Added in version 1.1

Raises:

ValueError –

Examples

This code with js_link:

select.js_link('value', plot, 'sizing_mode')

is equivalent to the following:

from bokeh.models import CustomJS
select.js_on_change('value',
    CustomJS(args=dict(other=plot),
             code="other.sizing_mode = this.value"
    )
)

Additionally, to use attr_selector to attach the left side of a range slider to a plot’s x_range:

range_slider.js_link('value', plot.x_range, 'start', attr_selector=0)

which is equivalent to:

from bokeh.models import CustomJS
range_slider.js_on_change('value',
    CustomJS(args=dict(other=plot.x_range),
             code="other.start = this.value[0]"
    )
)

js_on_change(event: str, *callbacks: JSChangeCallback) → None

Attach a CustomJS callback to an arbitrary BokehJS model event.

On the BokehJS side, change events for model properties have the form "change:property_name". As a convenience, if the event name passed to this method is also the name of a property on the model, then it will be prefixed with "change:" automatically:

# these two are equivalent
source.js_on_change('data', callback)
source.js_on_change('change:data', callback)

However, there are other kinds of events that can be useful to respond to, in addition to property change events. For example to run a callback whenever data is streamed to a ColumnDataSource, use the "stream" event on the source:

source.js_on_change('streaming', callback)

classmethod lookup(name: str, *, raises: bool = True) → PropertyDescriptor[Any] | None

Find the PropertyDescriptor for a Bokeh property on a class, given the property name.

Parameters:

• name (str) – name of the property to search for

• raises (bool) – whether to raise or return None if missing

Returns:

descriptor for property named name

Return type:

PropertyDescriptor

on_change(attr: str, *callbacks: PropertyCallback) → None

Add a callback on this object to trigger when attr changes.

Parameters:

• attr (str) – an attribute name on this object

• *callbacks (callable) – callback functions to register

Returns:

None

Examples

widget.on_change('value', callback1, callback2, ..., callback_n)

on_event(event: str | type[Event], *callbacks: EventCallback) → None

Run callbacks when the specified event occurs on this Model

Not all Events are supported for all Models. See specific Events in bokeh.events for more information on which Models are able to trigger them.

classmethod parameters() → list[Parameter]

Generate Python Parameter values suitable for functions that are derived from the glyph.

Returns:

list(Parameter)

classmethod properties(*, _with_props: bool = False) → set[str] | dict[str, Property[Any]]

Collect the names of properties on this class.

Warning

In a future version of Bokeh, this method will return a dictionary mapping property names to property objects. To future-proof this current usage of this method, wrap the return value in list.

Returns:

property names

classmethod properties_with_refs() → dict[str, Property[Any]]

Collect the names of all properties on this class that also have references.

This method always traverses the class hierarchy and includes properties defined on any parent classes.

Returns:

names of properties that have references

Return type:

set[str]

properties_with_values(*, include_defaults: bool = True, include_undefined: bool = False) → dict[str, Any]

Collect a dict mapping property names to their values.

This method always traverses the class hierarchy and includes properties defined on any parent classes.

Non-serializable properties are skipped and property values are in “serialized” format which may be slightly different from the values you would normally read from the properties; the intent of this method is to return the information needed to losslessly reconstitute the object instance.

Parameters:

include_defaults (bool, optional) – Whether to include properties that haven’t been explicitly set since the object was created. (default: True)

Returns:

mapping from property names to their values

Return type:

dict

query_properties_with_values(query: Callable[[PropertyDescriptor[Any]], bool], *, include_defaults: bool = True, include_undefined: bool = False) → dict[str, Any]

Query the properties values of HasProps instances with a predicate.

Parameters:

• query (callable) – A callable that accepts property descriptors and returns True or False

• include_defaults (bool, optional) – Whether to include properties that have not been explicitly set by a user (default: True)

Returns:

mapping of property names and values for matching properties

Return type:

dict

references() → set[Model]

Returns all Models that this object has references to.

remove_on_change(attr: str, *callbacks: Callable[[str, Any, Any], None]) → None

Remove a callback from this object

select(selector: SelectorType) → Iterable[Model]

Query this object and all of its references for objects that match the given selector.

Parameters:

selector (JSON-like)

Returns:

seq[Model]

select_one(selector: SelectorType) → Model | None

Query this object and all of its references for objects that match the given selector. Raises an error if more than one object is found. Returns single matching object, or None if nothing is found :param selector: :type selector: JSON-like

Returns:

Model

set_from_json(name: str, value: Any, *, setter: Setter | None = None) → None

Set a property value on this object from JSON.

Parameters:

• name – (str) : name of the attribute to set

• json – (JSON-value) : value to set to the attribute to

• models (dict or None, optional) –

  Mapping of model ids to models (default: None)

  This is needed in cases where the attributes to update also have values that have references.

• setter (ClientSession or ServerSession or None, optional) –

  This is used to prevent “boomerang” updates to Bokeh apps.

  In the context of a Bokeh server application, incoming updates to properties will be annotated with the session that is doing the updating. This value is propagated through any subsequent change notifications that the update triggers. The session can compare the event setter to itself, and suppress any updates that originate from itself.

Returns:

None

set_select(selector: type[Model] | SelectorType, updates: dict[str, Any]) → None

Update objects that match a given selector with the specified attribute/value updates.

Parameters:

• selector (JSON-like)

• updates (dict)

Returns:

None

themed_values() → dict[str, Any] | None

Get any theme-provided overrides.

Results are returned as a dict from property name to value, or None if no theme overrides any values for this instance.

Returns:

dict or None

to_serializable(serializer: Serializer) → ObjectRefRep

Converts this object to a serializable representation.

trigger(attr: str, old: Any, new: Any, hint: DocumentPatchedEvent | None = None, setter: Setter | None = None) → None

unapply_theme() → None

Remove any themed values and restore defaults.

Returns:

None

update(**kwargs: Any) → None

Updates the object’s properties from the given keyword arguments.

Returns:

None

Examples

The following are equivalent:

from bokeh.models import Range1d

r = Range1d

# set properties individually:
r.start = 10
r.end = 20

# update properties together:
r.update(start=10, end=20)

property document: Document | None

The Document this model is attached to (can be None)