Source code for panel.viewable

"""
Defines the baseclasses that make a component render to a bokeh model
and become viewable including:

* Layoutable: Defines parameters concerned with layout and style
* ServableMixin: Mixin class that defines methods to serve object on server
* Renderable: Defines methods to render a component as a bokeh model
* Viewable: Defines methods to view the component in the
  notebook, on the server or in static exports
"""
from __future__ import annotations

import asyncio
import logging
import os
import sys
import threading
import traceback
import uuid

from functools import partial
from typing import (
    IO, TYPE_CHECKING, Any, Callable, ClassVar, Dict, List, Mapping, Optional,
    TypeVar,
)

import param  # type: ignore

from bokeh.document import Document
from bokeh.resources import Resources
from jinja2 import Template
from pyviz_comms import Comm, JupyterCommManager  # type: ignore

from .config import config, panel_extension
from .io import serve
from .io.document import init_doc
from .io.embed import embed_state
from .io.loading import start_loading_spinner, stop_loading_spinner
from .io.model import add_to_doc, patch_cds_msg
from .io.notebook import (
    ipywidget, render_mimebundle, render_model, show_embed, show_server,
)
from .io.save import save
from .io.state import curdoc_locked, state
from .util import escape, param_reprs
from .util.warnings import deprecated

if TYPE_CHECKING:
    from bokeh.model import Model
    from bokeh.server.contexts import BokehSessionContext
    from bokeh.server.server import Server

    from .io.location import Location


[docs]class Layoutable(param.Parameterized): """ Layoutable defines shared style and layout related parameters for all Panel components with a visual representation. """ align = param.ClassSelector(default='start', class_=(str, tuple), doc=""" Whether the object should be aligned with the start, end or center of its container. If set as a tuple it will declare (vertical, horizontal) alignment.""") aspect_ratio = param.Parameter(default=None, doc=""" 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).""") background = param.Parameter(default=None, doc=""" Background color of the component.""") css_classes = param.List(default=None, doc=""" CSS classes to apply to the layout.""") width = param.Integer(default=None, bounds=(0, None), doc=""" The width of the component (in pixels). This can be either fixed or preferred width, depending on width sizing policy.""") height = param.Integer(default=None, bounds=(0, None), doc=""" The height of the component (in pixels). This can be either fixed or preferred height, depending on height sizing policy.""") min_width = param.Integer(default=None, bounds=(0, None), doc=""" Minimal width of the component (in pixels) if width is adjustable.""") min_height = param.Integer(default=None, bounds=(0, None), doc=""" Minimal height of the component (in pixels) if height is adjustable.""") max_width = param.Integer(default=None, bounds=(0, None), doc=""" Minimal width of the component (in pixels) if width is adjustable.""") max_height = param.Integer(default=None, bounds=(0, None), doc=""" Minimal height of the component (in pixels) if height is adjustable.""") margin = param.Parameter(default=5, doc=""" Allows to create additional space around the component. May be specified as a two-tuple of the form (vertical, horizontal) or a four-tuple (top, right, bottom, left).""") width_policy = param.ObjectSelector( default="auto", objects=['auto', 'fixed', 'fit', 'min', 'max'], doc=""" 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. """) height_policy = param.ObjectSelector( default="auto", objects=['auto', 'fixed', 'fit', 'min', 'max'], doc=""" 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. """) sizing_mode = param.ObjectSelector(default=None, objects=[ 'fixed', 'stretch_width', 'stretch_height', 'stretch_both', 'scale_width', 'scale_height', 'scale_both', None], doc=""" 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``). ``"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. """) visible = param.Boolean(default=True, doc=""" Whether the component is visible. Setting visible to false will hide the component entirely.""") __abstract = True def __init__(self, **params): if (params.get('width') is not None and params.get('height') is not None and params.get('width_policy') is None and params.get('height_policy') is None and 'sizing_mode' not in params): params['sizing_mode'] = 'fixed' elif (not (self.param.sizing_mode.constant or self.param.sizing_mode.readonly) and type(self).sizing_mode is None and 'sizing_mode' not in params): if config.sizing_mode == 'stretch_both': if params.get('height') is not None: params['sizing_mode'] = 'stretch_width' elif params.get('width') is not None: params['sizing_mode'] = 'stretch_height' else: params['sizing_mode'] = config.sizing_mode elif config.sizing_mode == 'stretch_width' and 'width' not in params: params['sizing_mode'] = config.sizing_mode elif config.sizing_mode == 'stretch_height' and 'height' not in params: params['sizing_mode'] = config.sizing_mode super().__init__(**params)
_Self = TypeVar('_Self', bound='ServableMixin') class ServableMixin(object): """ Mixin to define methods shared by objects which can served. """ def _modify_doc( self, server_id: str, title: str, doc: Document, location: Optional['Location'] ) -> Document: """ Callback to handle FunctionHandler document creation. """ if server_id: state._servers[server_id][2].append(doc) return self.server_doc(doc, title, location) # type: ignore def _add_location( self, doc: Document, location: Optional['Location' | bool], root: Optional['Model'] = None ) -> 'Location': from .io.location import Location if isinstance(location, Location): loc = location elif doc in state._locations: loc = state._locations[doc] else: loc = Location() state._locations[doc] = loc if root is None: loc_model = loc.get_root(doc) else: loc_model = loc._get_model(doc, root) loc_model.name = 'location' doc.add_root(loc_model) return loc def _on_msg(self, ref: str, manager, msg) -> None: """ Handles Protocol messages arriving from the client comm. """ root, doc, comm = state._views[ref][1:] patch_cds_msg(root, msg) held = doc.callbacks.hold_value patch = manager.assemble(msg) doc.hold() patch.apply_to_document(doc, comm.id if comm else None) doc.unhold() if held: doc.hold(held) def _on_error(self, ref: str, error: Exception) -> None: if ref not in state._handles or config.console_output in [None, 'disable']: return handle, accumulator = state._handles[ref] formatted = '\n<pre>'+escape(traceback.format_exc())+'</pre>\n' if config.console_output == 'accumulate': accumulator.append(formatted) elif config.console_output == 'replace': accumulator[:] = [formatted] if accumulator: handle.update({'text/html': '\n'.join(accumulator)}, raw=True) def _on_stdout(self, ref: str, stdout: Any) -> None: if ref not in state._handles or config.console_output is [None, 'disable']: return handle, accumulator = state._handles[ref] formatted = ["%s</br>" % o for o in stdout] if config.console_output == 'accumulate': accumulator.extend(formatted) elif config.console_output == 'replace': accumulator[:] = formatted if accumulator: handle.update({'text/html': '\n'.join(accumulator)}, raw=True) #---------------------------------------------------------------- # Public API #---------------------------------------------------------------- def servable( self, title: Optional[str] = None, location: bool | 'Location' = True, area: str = 'main', target: Optional[str] = None ) -> _Self: """ Serves the object or adds it to the configured pn.state.template if in a `panel serve` context, writes to the DOM if in a pyodide context and returns the Panel object to allow it to display itself in a notebook context. Arguments --------- title : str A string title to give the Document (if served as an app) location : boolean or panel.io.location.Location Whether to create a Location component to observe and set the URL location. area: str (deprecated) The area of a template to add the component too. Only has an effect if pn.config.template has been set. target: str Target area to write to. If a template has been configured on pn.config.template this refers to the target area in the template while in pyodide this refers to the ID of the DOM node to write to. Returns ------- The Panel object itself """ if curdoc_locked().session_context: logger = logging.getLogger('bokeh') for handler in logger.handlers: if isinstance(handler, logging.StreamHandler): handler.setLevel(logging.WARN) if config.template: area = target or area or 'main' template = state.template assert template is not None if template.title == template.param.title.default and title: template.title = title if area == 'main': template.main.append(self) elif area == 'sidebar': template.sidebar.append(self) elif area == 'modal': template.modal.append(self) elif area == 'header': template.header.append(self) else: self.server_doc(title=title, location=location) # type: ignore elif state._is_pyodide: from .io.pyodide import _get_pyscript_target, write target = target or _get_pyscript_target() if target is not None: asyncio.create_task(write(target, self)) return self def show( self, title: Optional[str] = None, port: int = 0, address: Optional[str] = None, websocket_origin: Optional[str] = None, threaded: bool = False, verbose: bool = True, open: bool = True, location: bool | 'Location' = True, **kwargs ) -> threading.Thread | 'Server': """ Starts a Bokeh server and displays the Viewable in a new tab. Arguments --------- title : str | None A string title to give the Document (if served as an app) port: int (optional, default=0) Allows specifying a specific port address : str The address the server should listen on for HTTP requests. websocket_origin: str or list(str) (optional) A list of hosts that can connect to the websocket. This is typically required when embedding a server app in an external web site. If None, "localhost" is used. threaded: boolean (optional, default=False) Whether to launch the Server on a separate thread, allowing interactive use. verbose: boolean (optional, default=True) Whether to print the address and port open : boolean (optional, default=True) Whether to open the server in a new browser tab location : boolean or panel.io.location.Location Whether to create a Location component to observe and set the URL location. Returns ------- server: bokeh.server.Server or threading.Thread Returns the Bokeh server instance or the thread the server was launched on (if threaded=True) """ return serve( self, port=port, address=address, websocket_origin=websocket_origin, show=open, start=True, title=title, verbose=verbose, location=location, threaded=threaded, **kwargs ) class Renderable(param.Parameterized): """ Baseclass for objects which can be rendered to a Bokeh model. It therefore declare APIs for initializing the models from parameter values. """ __abstract = True def __init__(self, **params): super().__init__(**params) self._callbacks = [] self._documents = {} self._models = {} self._comms = {} self._kernels = {} self._found_links = set() self._logger = logging.getLogger(f'{__name__}.{type(self).__name__}') def _log(self, msg: str, *args, level: str = 'debug') -> None: getattr(self._logger, level)(f'Session %s {msg}', id(state.curdoc), *args) def _get_model( self, doc: Document, root: Optional['Model'] = None, parent: Optional['Model'] = None, comm: Optional[Comm] = None ) -> 'Model': """ Converts the objects being wrapped by the viewable into a bokeh model that can be composed in a bokeh layout. Arguments ---------- doc: bokeh.Document Bokeh document the bokeh model will be attached to. root: bokeh.Model The root layout the viewable will become part of. parent: bokeh.Model The parent layout the viewable will become part of. comm: pyviz_comms.Comm Optional pyviz_comms when working in notebook Returns ------- model: bokeh.Model """ raise NotImplementedError def _cleanup(self, root: Model | None = None) -> None: """ Clean up method which is called when a Viewable is destroyed. Arguments --------- root: bokeh.model.Model Bokeh model for the view being cleaned up """ if root is None: return ref = root.ref['id'] if ref in state._handles: del state._handles[ref] def _preprocess(self, root: 'Model') -> None: """ Applies preprocessing hooks to the model. """ hooks = self._preprocessing_hooks+self._hooks for hook in hooks: hook(self, root) def _render_model(self, doc: Optional[Document] = None, comm: Optional[Comm] = None) -> 'Model': if doc is None: doc = Document() if comm is None: comm = state._comm_manager.get_server_comm() model = self.get_root(doc, comm) if config.embed: embed_state(self, model, doc, json=config.embed_json, json_prefix=config.embed_json_prefix, save_path=config.embed_save_path, load_path=config.embed_load_path, progress=False) else: add_to_doc(model, doc) return model def _init_params(self) -> Mapping[str, Any]: return {k: v for k, v in self.param.values().items() if v is not None} def _server_destroy(self, session_context: 'BokehSessionContext') -> None: """ Server lifecycle hook triggered when session is destroyed. """ doc = session_context._document if doc not in self._documents: return root = self._documents[doc] ref = root.ref['id'] self._cleanup(root) del self._documents[doc] if ref in state._views: del state._views[ref] def get_root( self, doc: Optional[Document] = None, comm: Optional[Comm] = None, preprocess: bool = True ) -> Model: """ Returns the root model and applies pre-processing hooks Arguments --------- doc: bokeh.Document Bokeh document the bokeh model will be attached to. comm: pyviz_comms.Comm Optional pyviz_comms when working in notebook preprocess: boolean (default=True) Whether to run preprocessing hooks Returns ------- Returns the bokeh model corresponding to this panel object """ doc = init_doc(doc) root = self._get_model(doc, comm=comm) if preprocess: self._preprocess(root) ref = root.ref['id'] state._views[ref] = (self, root, doc, comm) return root
[docs]class Viewable(Renderable, Layoutable, ServableMixin): """ Viewable is the baseclass all visual components in the panel library are built on. It defines the interface for declaring any object that displays itself by transforming the object(s) being wrapped into models that can be served using bokeh's layout engine. The class also defines various methods that allow Viewable objects to be displayed in the notebook and on bokeh server. """ loading = param.Boolean(doc=""" Whether or not the Viewable is loading. If True a loading spinner is shown on top of the Viewable.""") _preprocessing_hooks: ClassVar[List[Callable[['Viewable', 'Model'], None]]] = [] def __init__(self, **params): hooks = params.pop('hooks', []) super().__init__(**params) self._hooks = hooks self._update_loading() watcher = self.param.watch(self._update_loading, 'loading') self._callbacks.append(watcher) def _update_loading(self, *_) -> None: if self.loading: start_loading_spinner(self) else: stop_loading_spinner(self) def __repr__(self, depth: int = 0) -> str: return '{cls}({params})'.format(cls=type(self).__name__, params=', '.join(param_reprs(self))) def __str__(self) -> str: return self.__repr__() def _repr_mimebundle_(self, include=None, exclude=None): if state._is_pyodide: from .io.pyodide import ( _IN_WORKER, _get_pyscript_target, render_script, ) # If in pyodide and not in a worker we are probably in # PyScript otherwise we are probabably in JupyterLite if not _IN_WORKER: target = _get_pyscript_target() return {'text/html': render_script(self, target)}, {} loaded = panel_extension._loaded if not loaded and 'holoviews' in sys.modules: import holoviews as hv # type: ignore loaded = hv.extension._loaded if config.comms in ('vscode', 'ipywidgets'): widget = ipywidget(self) if hasattr(widget, '_repr_mimebundle_'): return widget._repr_mimebundle_(include=include, exclude=exclude), {} plaintext = repr(widget) if len(plaintext) > 110: plaintext = plaintext[:110] + '…' data = { 'text/plain': plaintext, } if widget._view_name is not None: data['application/vnd.jupyter.widget-view+json'] = { 'version_major': 2, 'version_minor': 0, 'model_id': widget._model_id } if config.comms == 'vscode': from IPython.display import display # type: ignore display(data, raw=True) return {'text/html': '<div style="display: none"></div>'}, {} return data, {} if not loaded: self.param.warning('Displaying Panel objects in the notebook ' 'requires the panel extension to be loaded. ' 'Ensure you run pn.extension() before ' 'displaying objects in the notebook.') return None if config.comms == 'colab': from .io.notebook import load_notebook load_notebook(config.inline) try: from IPython import get_ipython # type: ignore assert get_ipython().kernel is not None state._comm_manager = JupyterCommManager except Exception: pass if not state._views: # Initialize the global Location from .io.location import Location state._location = location = Location() else: location = None from IPython.display import display from .models.comm_manager import CommManager doc = Document() comm = state._comm_manager.get_server_comm() model = self._render_model(doc, comm) ref = model.ref['id'] manager = CommManager(comm_id=comm.id, plot_id=ref) client_comm = state._comm_manager.get_client_comm( on_msg=partial(self._on_msg, ref, manager), on_error=partial(self._on_error, ref), on_stdout=partial(self._on_stdout, ref) ) self._comms[ref] = (comm, client_comm) manager.client_comm_id = client_comm.id if config.console_output != 'disable': handle = display(display_id=uuid.uuid4().hex) state._handles[ref] = (handle, []) if config.embed: return render_model(model) return render_mimebundle(model, doc, comm, manager, location) #---------------------------------------------------------------- # Public API #----------------------------------------------------------------
[docs] def clone(self, **params) -> 'Viewable': """ Makes a copy of the object sharing the same parameters. Arguments --------- params: Keyword arguments override the parameters on the clone. Returns ------- Cloned Viewable object """ inherited = {p: v for p, v in self.param.values().items() if not self.param[p].readonly} return type(self)(**dict(inherited, **params))
[docs] def pprint(self) -> None: """ Prints a compositional repr of the class. """ deprecated('1.0', f'{type(self).__name__}.pprint', 'print') print(self)
[docs] def select( self, selector: Optional[type | Callable[['Viewable'], bool]] = None ) -> List['Viewable']: """ Iterates over the Viewable and any potential children in the applying the Selector. Arguments --------- selector: type or callable or None The selector allows selecting a subset of Viewables by declaring a type or callable function to filter by. Returns ------- viewables: list(Viewable) """ if (selector is None or (isinstance(selector, type) and isinstance(self, selector)) or (callable(selector) and not isinstance(selector, type) and selector(self))): return [self] else: return []
[docs] def app(self, notebook_url: str = "localhost:8888", port: int = 0) -> 'Server': """ Displays a bokeh server app inline in the notebook. Arguments --------- notebook_url: str URL to the notebook server port: int (optional, default=0) Allows specifying a specific port """ deprecated('1.0', f'{type(self).__name__}.app', 'panel.io.notebook.show_server') return show_server(self, notebook_url, port)
[docs] def embed( self, max_states: int = 1000, max_opts: int = 3, json: bool = False, json_prefix: str = '', save_path: str = './', load_path: Optional[str] = None, progress: bool = False, states={} ) -> None: """ Renders a static version of a panel in a notebook by evaluating the set of states defined by the widgets in the model. Note this will only work well for simple apps with a relatively small state space. Arguments --------- max_states: int The maximum number of states to embed max_opts: int The maximum number of states for a single widget json: boolean (default=True) Whether to export the data to json files json_prefix: str (default='') Prefix for JSON filename save_path: str (default='./') The path to save json files to load_path: str (default=None) The path or URL the json files will be loaded from. progress: boolean (default=False) Whether to report progress states: dict (default={}) A dictionary specifying the widget values to embed for each widget """ show_embed( self, max_states, max_opts, json, json_prefix, save_path, load_path, progress, states )
[docs] def save( self, filename: str | os.PathLike | IO, title: Optional[str] = None, resources: Resources | None = None, template: str | Template | None = None, template_variables: Dict[str, Any] = {}, embed: bool = False, max_states: int = 1000, max_opts: int = 3, embed_json: bool = False, json_prefix: str='', save_path: str='./', load_path: Optional[str] = None, progress: bool = True, embed_states: Dict[Any, Any] = {}, as_png: bool | None = None, **kwargs ) -> None: """ Saves Panel objects to file. Arguments --------- filename: str or file-like object Filename to save the plot to title: string Optional title for the plot resources: bokeh resources One of the valid bokeh.resources (e.g. CDN or INLINE) template: passed to underlying io.save template_variables: passed to underlying io.save embed: bool Whether the state space should be embedded in the saved file. max_states: int The maximum number of states to embed max_opts: int The maximum number of states for a single widget embed_json: boolean (default=True) Whether to export the data to json files json_prefix: str (default='') Prefix for the auto-generated json directory save_path: str (default='./') The path to save json files to load_path: str (default=None) The path or URL the json files will be loaded from. progress: boolean (default=True) Whether to report progress embed_states: dict (default={}) A dictionary specifying the widget values to embed for each widget as_png: boolean (default=None) To save as a .png. If None save_png will be true if filename is string and ends with png. """ return save( self, filename, title, resources, template, template_variables, embed, max_states, max_opts, embed_json, json_prefix, save_path, load_path, progress, embed_states, as_png, **kwargs )
[docs] def server_doc( self, doc: Optional[Document] = None, title: Optional[str] = None, location: bool | 'Location' = True ) -> Document: """ Returns a serveable bokeh Document with the panel attached Arguments --------- doc : bokeh.Document (optional) The bokeh Document to attach the panel to as a root, defaults to bokeh.io.curdoc() title : str A string title to give the Document location : boolean or panel.io.location.Location Whether to create a Location component to observe and set the URL location. Returns ------- doc : bokeh.Document The bokeh document the panel was attached to """ doc = init_doc(doc) if title or doc.title == 'Bokeh Application': title = title or 'Panel Application' doc.title = title model = self.get_root(doc) doc.on_session_destroyed(state._destroy_session) doc.on_session_destroyed(self._server_destroy) # type: ignore self._documents[doc] = model add_to_doc(model, doc) if location: self._add_location(doc, location, model) if config.notifications and doc is state.curdoc: notification_model = state.notifications._get_model(doc, model) notification_model.name = 'notifications' doc.add_root(notification_model) return doc
[docs]class Viewer(param.Parameterized): """ A baseclass for custom components that behave like a Panel object. By implementing __panel__ method an instance of this class will behave like the returned Panel component when placed in a layout, render itself in a notebook and provide show and servable methods. """ def __panel__(self) -> Viewable: """ Subclasses should return a Panel component to be rendered. """ raise NotImplementedError def _create_view(self): from .pane import panel from .param import ParamMethod if hasattr(self.__panel__, "_dinfo"): view = ParamMethod(self.__panel__, lazy=True) else: view = panel(self.__panel__()) return view
[docs] def servable( self, title: Optional[str]=None, location: bool | 'Location' = True, area: str = 'main', target: Optional[str] = None ) -> Viewable: return self._create_view().servable(title, location, area, target)
servable.__doc__ = ServableMixin.servable.__doc__
[docs] def show( self, title: Optional[str] = None, port: int = 0, address: Optional[str] = None, websocket_origin: Optional[str] = None, threaded: bool = False, verbose: bool = True, open: bool = True, location: bool | 'Location' = True, **kwargs ) -> threading.Thread | 'Server': return self._create_view().show( title, port, address, websocket_origin, threaded, verbose, open, location, **kwargs )
show.__doc__ = ServableMixin.show.__doc__ def _repr_mimebundle_(self, include=None, exclude=None): return self._create_view()._repr_mimebundle_(include, exclude)
__all__ = ( "Layoutable", "Viewable", "Viewer" )